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MCP73871
Stand-Alone System Load Sharing and Li-Ion / Li-Polymer Battery Charge Management Controller
Features
* Integrated System Load Sharing and Battery Charge Management - Simultaneously Power the System and Charge the Li-Ion Battery - Voltage Proportional Current Control (VPCC) ensures system load has priority over Li-Ion battery charge current - Low-Loss Power-Path Management with Ideal Diode Operation * Complete Linear Charge Management Controller - Integrated Pass Transistors - Integrated Current Sense - Integrated Reverse Discharge Protection - Selectable Input Power Sources: USB Port or AC-DC Wall Adapter * Preset High Accuracy Charge Voltage Options: - 4.10V, 4.20V, 4.35V or 4.40V - 0.5% Regulation Tolerance * Constant Current / Constant Voltage (CC/CV) Operation with Thermal Regulation * Maximum 1.8A Total Input Current Control * Resistor Programmable Fast Charge Current Control: 50 mA to 1A * Resistor Programmable Termination Set Point * Selectable USB Input Current Control - Absolute Maximum: 100 mA (L) / 500 mA (H) * Automatic Recharge * Automatic End-of-Charge Control * Safety Timer With Timer Enable/Disable Control * 0.1C Preconditioning for Deeply Depleted Cells * Battery Cell Temperature Monitor * Undervoltage Lockout (UVLO) * Low Battery Status Indicator (LBO) * Power-Good Status Indicator (PG) * Charge Status and Fault Condition Indicators * Numerous Selectable Options Available for a Variety of Applications: - Refer to Section 1.0 "Electrical Characteristics" for Selectable Options" - Refer to the "Product Identification System" for Standard Options * Temperature Range: -40C to +85C * Packaging: 20-Lead QFN (4 mm x 4 mm)
Applications
* * * * * * * * GPSs / Navigators PDAs and Smart Phones Portable Media Players and MP3 Players Digital Cameras Bluetooth Headsets Portable Medical Devices Charge Cradles / Docking Stations Toys
Description
The MCP73871 device is a fully integrated linear solution for system load sharing and Li-Ion / Li-Polymer battery charge management with ac-dc wall adapter and USB port power sources selection. It's also capable of autonomous power source selection between input or battery. Along with its small physical size, the low number of required external components makes the device ideally suited for portable applications. The MCP73871 device automatically obtains power for the system load from a single-cell Li-Ion battery or an input power source (ac-dc wall adapter or USB port). The MCP73871 device specifically adheres to the current drawn limits governed by the USB specification. With an ac-dc wall adapter providing power to the system, an external resistor sets the magnitude of 1A maximum charge current while supports up to 1.8A total current for system load and battery charge current. The MCP73871 device employs a constant current / constant voltage (CC/CV) charge algorithm with selectable charge termination point. The constant voltage regulation is fixed with four available options: 4.10V, 4.20V, 4.35V, or 4.40V to accommodate new, emerging battery charging requirements. The MCP73871 device also limits the charge current based on die temperature during high power or high ambient conditions. This thermal regulation optimizes the charge cycle time while maintaining device reliability. The MCP73871 device includes a low battery indicator, a power-good indicator and two charge status indicators that allows for outputs with LEDs or communication with host microcontrollers. The MCP73871 device is fully specified over the ambient temperature range of -40C to +85C.
(c) 2009 Microchip Technology Inc.
DS22090B-page 1
MCP73871
Package Types
MCP73871 20-Lead QFN CE VBAT_SENSE
OUT OUT 1 VPCC 2 SEL 3 PROG2 4 THERM 5
6
IN
20 19 18 17 16 15
IN
VBAT PROG1 PROG3 VSS
EP 21
14 VBAT 13 12 11
7
8
9 10
PG STAT2
Typical Application Circuit
MCP73871 Typical Application
Ac-dc Adapter or USB Port 10 F 470
18, 19 2
STAT1 / LBO
TE VSS
IN VPCC
OUT
1, 20 4.7 F
System Load
VBAT 14, 15, 16 4.7 F THERM 5 NTC 10 k
6
PG
470 470
7 STAT2 8 3 STAT1 LBO SEL 4 PROG2 TE CE
PROG1
13
RPROG1
Single-Cell Li-Ion Battery
Low Low Low Low
Hi Hi 9 Hi 17 Hi
PROG3
12 RPROG3
VSS 10, 11, EP
DS22090B-page 2
(c) 2009 Microchip Technology Inc.
MCP73871
Functional Block Diagram
Direction Control IN 0.2 OUT
G=0.001 CURRENT LIMIT + VREF Direction Control VBAT PROG1 G=0.001 G=0.001 G=0.001 CURRENT LIMIT + VREF/2 PROG3 VREF VPCC + CA + VREF PRECONDITION + VREF VREF VBAT_SENSE SEL PROG2 CHRG + VA + VREF PG TERM STAT1 + UVLO, REFERENCE, CHARGE CONTROL, TIMER, AND STATUS LOGIC VREF HTVT VREF 50 A THERM + STAT2 TE CE VSS LTVT + 0.2 Ideal Diode, Synchronous Switch
(c) 2009 Microchip Technology Inc.
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DS22090B-page 3
MCP73871
NOTES:
DS22090B-page 4
(c) 2009 Microchip Technology Inc.
MCP73871
1.0 ELECTRICAL CHARACTERISTICS
Notice: Stresses above those listed under "Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability.
Absolute Maximum Ratings
VIN ....................................................................................7.0V All Inputs and Outputs w.r.t. ................ VSS-0.3V to VDD+0.3V (VDD = VIN or VBAT) Maximum Junction Temperature, TJ ............ Internally Limited Storage temperature .....................................-65C to +150C ESD protection on all pins Human Body Model (1.5 k in Series with 100pF) ........ 4 kV Machine Model (200 pF, No Series Resistance) .............300V
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = VREG + 0.3V to 6V, TA = -40C to +85C. Typical values are at +25C, VIN = [VREG (typical) + 1.0V] Parameters Supply Input Supply Voltage Supply Current VIN ISS VREG +0.3V -- -- -- -- -- 2500 260 180 28 6 3750 350 300 50 V A A A A Charging Charge Complete Standby Shutdown (VDD < VBAT - 100 mV or VDD < VSTOP) VDD= Low-to-High VDD= High-to-Low Sym Min Typ Max Units Conditions
UVLO Start Threshold UVLO Stop Threshold UVLO Hysteresis Regulated Charge Voltage
VSTART VSTOP VHYS VREG
VREG + 0.05V VREG - 0.07V -- 4.080 4.179 4.328 4.378
VREG + 0.15V VREG + 0.07V 90 4.10 4.20 4.35 4.40 -- -- 0.08 0.08 -47 -40 100 1000 90 450
VREG + 0.25V VREG + 0.17V -- 4.121 4.221 4.372 4.422 +0.5 +0.75 0.20 0.18 -- -- 110 1100 100 500
V V mV V V V % % %/V % dB dB mA mA mA mA
Voltage Regulation (Constant Voltage Mode) VDD=[VREG(typical)+1V] IOUT=10 mA TA=-5C to +55C TA= +25C TA= -5C to +55C VDD=[VREG(typical)+1V] to 6V IOUT=10 mA IOUT=10 mA to 150 mA VDD= [VREG(typical)+1V] IOUT=10 mA, 1 kHz IOUT=10 mA, 10 kHz PROG1 = 10 k PROG1 = 1 k, TA=-5C to +55C, SEL = Hi USB Fast Charge Current IREG 80 400 PROG2 = Low, SEL = Low, (Note 2) PROG2 = High, SEL = Low, (Note 2) TA= -5C to +55C Note 1: 2: The value is ensured by design and not production tested. The maximum available charge current is also limited by the value set at PROG1 input.
Regulated Charge Voltage Tolerance Line Regulation Load Regulation Supply Ripple Attenuation
VRTOL |(VBAT/VBAT)/ VDD| |VBAT/VBAT| PSRR
-0.5 -0.75 -- -- -- --
Current Regulation (Fast Charge Constant-Current Mode) AC-Adapter Fast Charge Current IREG 90 900
(c) 2009 Microchip Technology Inc.
DS22090B-page 5
MCP73871
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = VREG + 0.3V to 6V, TA = -40C to +85C. Typical values are at +25C, VIN = [VREG (typical) + 1.0V] Parameters Input Current Limit Control (ICLC) USB-Port Supply Current Limit ILIMIT_USB 80 400 AC-DC Adapter Current Limit VPCC Input Threshold VPCC Input Threshold Tolerance Input Leakage Current Precondition Current Ratio Precondition Current Threshold Ratio Precondition Hysteresis Automatic Charge Termination Set Point Charge Termination Current Ratio ITERM 75 7.5 Automatic Recharge Recharge Voltage Threshold Ratio IN-to-OUT Pass Transistor ON-Resistance ON-Resistance Charge Transistor ON-Resistance ON-Resistance ON-Resistance Battery Discharge Current Output Reverse Leakage Current IDISCHARGE -- -- -- -- Status Indicators - STAT1 (LBO), STAT2, PG Sink Current Low Output Voltage Input Leakage Current Low Battery Indicator (LBO) Low Battery Detection Threshold VLBO -- 2.85 2.95 3.05 Low Battery Detection Hysteresis Note 1: 2: VLBO_HYS -- Disable 3.0 3.1 3.2 150 -- 3.15 3.25 3.35 -- V V V mV VBAT Low-to-High VBAT > VIN, PG = Hi-Z TA=-5C to +55C ISINK VOL ILK -- -- -- 16 0.4 0.01 35 1 1 mA V A ISINK = 4 mA High Impedance, VDD on pin 30 30 30 -6 40 40 40 -13 A A A A Shutdown (VBAT < VDD < VUVLO) Shutdown (0 < VDD < VBAT) VBAT = Power Out, No Load Charge Complete RDSON_ RDS_ON -- -- 200 200 -- -- m m VDD = 4.5V, TJ = 105C VDD = 4.5V, TJ = 105C BAT-to-OUT Pass Transistor ON-Resistance RDS_ON -- 200 -- m VDD = 4.5V, TJ = 105C VRTH VREG 0.21V VREG 0.15V VREG 0.09V V VBAT High-to-Low 100 10 125 12.5 mA mA PROG3 = 10 k PROG3 = 100 k TA=-5C to +55C ILIMIT_AC VVPCC VRTOL ILK IPREG / IREG VPTH / VREG VPHYS 1500 -- -3 -- 7.5 69 -- 90 450 1650 1.23 -- 0.01 10 72 105 100 500 1800 -- +3 1 12.5 75 -- mA mA mA V % A % % mV PROG2 = Low, SEL = Low PROG2 = High, SEL = Low TA=-5C to +55C SEL = High, TA=-5C to +55C IOUT=10 mA TA=-5C to +55C VVPCC = VDD PROG1 = 1.0 k to 10 k TA=-5C to +55C VBAT Low-to-High VBAT High-to-Low Voltage Proportional Charge Control (VPCC - Input Voltage Regulation) Sym Min Typ Max Units Conditions
Precondition Current Regulation (Trickle Charge Constant-Current Mode)
The value is ensured by design and not production tested. The maximum available charge current is also limited by the value set at PROG1 input.
DS22090B-page 6
(c) 2009 Microchip Technology Inc.
MCP73871
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = VREG + 0.3V to 6V, TA = -40C to +85C. Typical values are at +25C, VIN = [VREG (typical) + 1.0V] Parameters PROG1 Input (PROG1) Charge Impedance Range PROG3 Input (PROG3) Termination Impedance Range PROG2 Input (PROG2) Input High Voltage Level Input Low Voltage Level Input Leakage Current Timer Enable (TE) Input High Voltage Level Input Low Voltage Level Input Leakage Current Chip Enable (CE) Input High Voltage Level Input Low Voltage Level Input Leakage Current Input Source Selection (SEL) Input High Voltage Level Input Low Voltage Level Input Leakage Current Thermistor Bias Thermistor Current Source Thermistor Comparator Upper Trip Threshold Upper Trip Point Hysteresis Lower Trip Threshold Lower Trip Point Hysteresis Thermal Shutdown Die Temperature Die Temperature Hysteresis Note 1: 2: TSD TSDHYS -- -- 150 10 -- -- C C VT1 VT1HYS VT2 VT2HYS 1.20 -- 0.23 -- 1.24 -40 0.25 40 1.26 -- 0.27 -- V mV V mV VT2 High-to-Low VT1 Low-to-High ITHERM 47 50 53 A 2 k < RTHERM < 50 k VIH VIL ILK 1.8 -- -- -- -- 0.01 -- 0.8 1 V V A VSEL = VDD VIH VIL ILK 1.8 -- -- -- -- 0.01 -- 0.8 1 V V A VCE = VDD VIH VIL ILK 1.8 -- -- -- -- 0.01 -- 0.8 1 V V A Note 1 Note 1 VTE = VDD VIH VIL ILK 1.8 -- -- -- -- 0.01 -- 0.8 1 V V A VPROG2 = VDD RPROG 5 -- 100 k RPROG 1 -- 20 k Sym Min Typ Max Units Conditions
The value is ensured by design and not production tested. The maximum available charge current is also limited by the value set at PROG1 input.
(c) 2009 Microchip Technology Inc.
DS22090B-page 7
MCP73871
AC CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = 4.6V to 6V. Typical values are at +25C, VDD = [VREG (typical) + 1.0V] Parameters UVLO Start Delay Current Regulation Transition Time Out of Precondition Current Rise Time Out of Precondition Precondition Comparator Filter Time Termination Comparator Filter Time Charge Comparator Filter Time Thermistor Comparator Filter Time Elapsed Timer Elapsed Timer Period tELAPSED -- 3.6 5.4 7.2 Status Indicators Status Output Turn-off Status Output Turn-on Note 1: tOFF tON -- -- -- -- 500 500 s s ISINK = 1 mA to 0 mA ISINK = 0 mA to 1 mA 0 4.0 6.0 8.0 -- 4.4 6.6 8.8 Hours Hours Hours Hours tDELAY tRISE tPRECON tTERM tCHARGE tTHERM -- -- 0.4 0.4 0.4 0.4 -- -- 1.3 1.3 1.3 1.3 10 10 3.2 3.2 3.2 3.2 ms ms ms ms ms ms VBAT < VPTH to VBAT > VPTH IOUT Rising to 90% of IREG Average VBAT Rise/Fall Average IOUT Falling Average VBAT Falling Average THERM Rise/Fall Sym tSTART Min -- Typ -- Max 5 Units ms Conditions VDD Low-to-High
Internal safety timer is tested base on internal oscillator frequency measurement.
TEMPERATURE SPECIFICATIONS
Electrical Specifications: Unless otherwise indicated, all limits apply for VIN = 4.6V to 6V. Typical values are at +25C, VDD = [VREG (typical) + 1.0V] Parameters Temperature Ranges Specified Temperature Range Operating Temperature Range Storage Temperature Range Thermal Package Resistances Thermal Resistance, 20LD-QFN, 4x4 JA -- 35 -- C/W 4-Layer JC51-7 Standard Board, Natural Convection TA TJ TA -40 -40 -65 -- -- -- +85 +125 +150 C C C Sym Min Typ Max Units Conditions
DS22090B-page 8
(c) 2009 Microchip Technology Inc.
MCP73871
2.0
Note:
TYPICAL PERFORMANCE CURVES
The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
Note: Unless otherwise indicated, VIN = [VREG(typical) + 1V], IOUT = 10 mA and TA= +25C, Constant-voltage mode.
4.240
Battery Regulation Voltage (V)
4.232 4.224 4.216 4.208 4.200 4.192 4.184 4.176
4.6
Temperature = +25C
IOUT= 900 mA IOUT= 500 mA IOUT= 100 mA IOUT= 10 mA
4.300 4.280 4.260 4.240 4.220 4.200 4.180 4.160 4.140 4.120 4.100
500 100 200 300 400 0
Battery Regulation Voltage (V)
Temperature = +25C VDD = 5.2V
800
600
700
900
4.9
5.1 5.4 5.6 Supply Voltage (V)
5.9
Charge Current (mA)
FIGURE 2-1: Battery Regulation Voltage (VBAT) vs. Supply Voltage (VDD).
FIGURE 2-4: Charge Current (IOUT) vs. Battery Regulation Voltage (VBAT).
40.0
Battery Regulation Voltage (V)
Battery Discharge Current (A)
4.238 4.230 4.222 4.214 4.206 4.198 4.190
IOUT = 500 mA IOUT = 100 mA IOUT = 10 mA IOUT = 1000 mA
35.0 30.0 25.0 20.0 15.0 10.0
VBAT = 4.2V VDD= Floating
-45
-30
-15 0 15 30 45 60 Ambient Temperature (C)
75
90
-45
-30
-15
0 15 30 45 Temperature (C)
60
75
FIGURE 2-2: Battery Regulation Voltage (VBAT) vs. Ambient Temperature (TA).
1000 900 800 700 600 500 400 300 200 100 0
FIGURE 2-5: Output Leakage Current (IDISCHARGE) vs. Ambient Temperature (TA).
35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 3.0 3.2 3.4 3.6 3.8 Battery Voltage (V) 4.0 4.2
1 2 3 4 5 6 7 8 9 10 11 1213 14 151617 18 1920 RPROG (k)
FIGURE 2-3: Charge Current (IOUT) vs. Programming Resistor (RPROG).
FIGURE 2-6: Output Leakage Current (IDISCHARGE) vs. Battery Regulation Voltage (VBAT).
(c) 2009 Microchip Technology Inc.
Battery Discharge Current (A)
VDD= 5.2V Temperature = +25C
VDD= VBAT Temperature = +25C
IREG (mA)
DS22090B-page 9
1000
90
MCP73871
Note: Unless otherwise indicated, VIN = [VREG(typical) + 1V], IOUT = 10 mA and TA= +25C, Constant-voltage mode.
35.0
Battery Discharge Current (A)
30.0 25.0 20.0 15.0 10.0 5.0 0.0
VDD= Floating Temperature = +25C
110 108 106 104 102 100 98 96 94 92 90
RPROG = 10 k Temperature = +25C
3.0
3.2
3.4 3.6 3.8 Battery Voltage (V)
4.0
4.2
IREG (mA)
4.5
4.8
5.0 5.3 5.5 Supply Voltage (V)
5.8
6.0
FIGURE 2-7: Output Leakage Current (IDISCHARGE) vs. Battery Voltage (VBAT).
1190 1160 1130 1100 1070 1040 1010 980 950 920 890 860 830 800
FIGURE 2-10: Charge Current (IOUT) vs. Supply Voltage (VDD).
1100 1060 1020 980 940 900 860 820 780 740 700 -45 -30
Charge Current (mA)
RPROG = 1 k Temperature = +25C
IREG (mA)
RPROG = 1 k VDD = 5.2V
4.5
4.8
5.0 5.3 5.5 Supply Voltage (V)
5.8
6.0
-15 0 15 30 45 60 Ambient Temperature (C)
75
90
FIGURE 2-8: Charge Current (IOUT) vs. Supply Voltage (VDD).
550 540 530 520 510 500 490 480 470 460 450
FIGURE 2-11: Charge Current (IOUT) vs. Ambient Temperature (TA).
110 108 106 104 102 100 98 96 94 92 90 -45 -30
Charge Current (mA)
RPROG = 2 k Temperature = +25C
IREG (mA)
RPROG = 10 k VDD = 5.2V
4.5
4.8
5.0 5.3 5.5 Supply Voltage (V)
5.8
6.0
-15 0 15 30 45 60 Ambient Temperature (C)
75
90
FIGURE 2-9: Charge Current (IOUT) vs. Supply Voltage (VDD).
FIGURE 2-12: Charge Current (IOUT) vs. Ambient Temperature (TA).
DS22090B-page 10
(c) 2009 Microchip Technology Inc.
MCP73871
Note: Unless otherwise indicated, VIN = [VREG(typical) + 1V], IOUT = 10 mA and TA= +25C, Constant-voltage mode.
55
Charge Current (mA)
Charge Current (mA) 120
R PROG = 20 k VDD = 5.2V
53 51 49 47 45 43 41
100 80 60 40 20 0
VDD = 5.2V RPROG = 10 k
-45
-30
-15 0 15 30 45 60 Ambient Temperature (C)
75
90
25
50
75
100
125
150
Ambient Temperature (C)
FIGURE 2-13: Charge Current (IOUT) vs. Ambient Temperature (TA).
1200
Charge Current (mA)
FIGURE 2-16: Charge Current (IOUT) vs. Junction Temperature (TJ).
52.0 51.5 51.0 50.5 50.0 49.5 49.0 48.5 48.0 47.5 47.0
1000 800 600 400 200 0 25 50 75 100 125 150 Ambient Temperature (C)
VDD = 5.2V RPROG = 1 k
Thermistor Current (A)
Temperature = +25C
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
Supply Voltage (V)
FIGURE 2-14: Charge Current (IOUT) vs. Junction Temperature (TJ).
600 Charge Current (mA) 500 400 300 200 100 0 25 50 75 100 125 150 Ambient Temperature (C)
VDD = 5.2V RPROG = 2 k
FIGURE 2-17: Thermistor Current (ITHERM) vs. Supply Voltage (VDD).
52.0 51.5 51.0 50.5 50.0 49.5 49.0 48.5 48.0 47.5 47.0
Thermistor Current (A)
VDD = 5.2V
-45
-30
-15 0 15 30 45 60 Ambient Temperature (C)
75
90
FIGURE 2-15: Charge Current (IOUT) vs. Junction Temperature (TJ).
FIGURE 2-18: Thermistor Current (ITHERM) vs. Ambient Temperature (TA).
(c) 2009 Microchip Technology Inc.
DS22090B-page 11
MCP73871
Note: Unless otherwise indicated, VIN = [VREG(typical) + 1V], IOUT = 10 mA and TA= +25C, Constant-voltage mode.
0
IOUT = 10 mA
Output Current (A)
PSRR (dB)
-20 -30 -40 -50 -60 0.01
0 -0.1 -0.2 -0.3 -0.4 0.002 0.003 -0.5 0.004
0.1
1
10
100
1000
Frequency (kHz)
Time (s)
FIGURE 2-19: Power Supply Ripple Rejection (PSRR).
9 8.5 Output Voltage (V) 8 7.5 7 6.5 6 5.5 5 4.5 -0.0008 -0.0006 -0.0004 -0.0002 Time (s) 0 -0.7 0.0002 0.3
FIGURE 2-22: IOUT = 100 mA.
1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 -0.2
75 00 .0 0
Load Transient Response.
Output Current (A)
0.1 -0.1 -0.3 -0.5
Output Current (A)
0 -0.1 -0.2 -0.3 -0.4 -0.5
15 01 .0 0
55 01 .0 0
95 01 .0 0
Time (s)
35 02 .0 0
75 02 .0 0
FIGURE 2-20: IOUT = 100 mA.
Line Transient Response.
FIGURE 2-23: IOUT = 500 mA.
Load Transient Response.
9 IOUT = 500 mA 8.5 8 7.5 7 6.5 6 5.5 5 4.5 4 -0.0008 -0.0006 -0.0004 -0.0002 Time (s)
0.7 0.6 Output Current (A)
Output Voltage (V)
Input Voltage (V)
0.5 0.4 0.3 0.2 0.1 0 0 0.0002
Time (ms)
FIGURE 2-21: IOUT = 500 mA.
Line Transient Response.
FIGURE 2-24:
Undervoltage Lockout.
DS22090B-page 12
(c) 2009 Microchip Technology Inc.
UVLO (V)
Output Ripple (V)
IOUT = 100 mA
IOUT = 500 mA
0.2 0.1
Output Ripple (V)
-10
1.8 I = 100 mA 1.6 OUT 1.4 1.2 1 0.8 0.6 0.4 0.2 0 -0.2 -0.001 0 0.001
0.2 0.1
MCP73871
Note: Unless otherwise indicated, VIN = [VREG(typical) + 1V], IOUT = 10 mA and TA= +25C, Constant-voltage mode.
4.5 4 Charge Voltage (V) 3.5 3 2.5 2 1.5 1 0.5 0 0 10 20 30 40 50 60 70 80
MCP73871 VDD = 5.2V RPROG1 = 1 k RPROG3 = 25 k
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0
Time (ms)
Startup Voltage (V)
Input Voltage (V)
Time (Minute)
FIGURE 2-25:
Startup Delay.
FIGURE 2-27: Complete Charge Cycle (1000 mAh Li-Ion Battery).
0.5
Charge Voltage (V) 4.5 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 1
4.5 4 Charge Voltage (V) 3.5 3 2.5 2 1.5 1 0.5 0 0 0.1 0.2 0.3 0.4 0.5 Time (Minutes)
MCP73871 VDD = 5.2V SEL = Low PROG2 = Low
3.5 3 2.5 2 1.5 1 0.5
Preconditioning Fast Charge (Constant Current) Preconditioning Threshold Voltage
0.3 0.2 0.1 0
MCP73871 VDD = 5.2V RPROG1 = 1 k RPROG3 = 25 k
0 0 0.2 0.4 0.6 0.8 Time (Minute)
FIGURE 2-26: Complete Charge Cycle (130 mAh Li-Ion Battery).
FIGURE 2-28: Typical Charge Profile in Preconditioning (1000 mAh Battery).
(c) 2009 Microchip Technology Inc.
DS22090B-page 13
Charge Current (A)
0.4
Charge Current (A)
4
Charge Current (A)
MCP73871
NOTES:
DS22090B-page 14
(c) 2009 Microchip Technology Inc.
MCP73871
3.0 PIN DESCRIPTION
PIN FUNCTION TABLES
Symbol OUT VPCC SEL PROG2 THERM PG STAT2 STAT1 / LBO TE VSS I/O O I I I I/O O O O I -- System Output Terminal Voltage proportional charge control Input type selection (Low for USB port, High for ac-dc adapter) USB port input current limit selection when SEL = Low. (Low = 100 mA, High = 500 mA) Thermistor monitoring input and bias current Power-Good Status Output (Open-Drain) Charge Status Output 2 (Open-Drain) Charge Status Output 1 (Open-Drain). Low battery output indicator when VBAT > VIN Timer Enable; Enables Safety Timer when active Low Battery Management 0V Reference. EP (Exposed Thermal Pad); There is an internal electrical connection between the exposed thermal pad and VSS. The EP must be connected to the same potential as the VSS pin on the Printed Circuit Board (PCB) Termination set point for both ac-dc adapter and USB port Fast charge current regulation setting with SEL = High. Preconditioning set point for both USB port and ac-dc adapter. Battery Positive Input and Output connection Battery Voltage Sense Device Charge Enable; Enabled when CE = High Power Supply Input. Function The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
Pin Number 1, 20 2 3 4 5 6 7 8 9 10, 11, EP
12 13 14, 15 16 17 18, 19 Note:
PROG3 PROG1 VBAT VBAT_SENSE CE IN
I/O I/O I/O I/O I I
Legend: I = Input, O = Output, I/O = Input/Output The input pins should always tie to either High or Low, and never allow floating to ensure operation properly.
3.1
Power Supply Input (IN)
3.3
A supply voltage of VREG + 0.3V to 6V is recommended. Bypass to VSS with a minimum of 4.7 F.
Voltage Proportional Charge Control (VPCC)
3.2
System Output Terminal (OUT)
The MCP73871 device powers the system via output terminals while independently charging the battery. This feature reduces the charge and discharge cycles on the battery, allows for proper charge termination and the system to run with an absent or defective battery pack. Also, this feature gives the system priority on input power, allowing the system to power-up with deeply depleted battery packs. Bypass to VSS with a minimum of 4.7 F is recommended.
If the voltage on the IN pin drops to a preset value, determined by the threshold established at the VPCC input, due to a limited amount of input current or input source impedance, the battery charging current is reduced. Further demand from the system is supported by the battery, if possible. To active this feature, simply supply 1.23V or greater to VPCC pin. This feature can be disabled by connecting the VPCC pin to IN. For example, a system is designed with a 5.5V rated DC power supply with 0.5V tolerance. The worst condition of 5V is selected, which is used to calculate the VPCC supply voltage with divider.
(c) 2009 Microchip Technology Inc.
DS22090B-page 15
MCP73871
The voltage divider equation is shown below: R2 V VPCC = ------------------ x V IN = 1.23V R 1 + R 2 110k 1.23V = ----------------------------- x 5V 110k + R 1 R 1 = 337.2k The calculated R1 equals to 337.2 k when 110 k is selected for R2. The 330 k resistor is selected for R1 to build the voltage divider for VPCC. VIN 330 k VPCC 110 k
3.8
Charge Current Regulation Set (PROG1)
The maximum constant charge current is set by placing a resistor from PROG1 to VSS. PROG1 sets the maximum constant charge current for both ac-dc adapter and USB port. However, the actual charge current is based on input source type and system load requirement.
3.9
USB-Port Current Regulation Set (PROG2)
The MCP73871 device USB-Port current regulation set input (PROG2) is a digital input selection. A logic Low selects a 1 unit load input current from USB port (100 mA); a logic High selects a 5 unit loads input current from USB port (500 mA).
3.10
Charge Status Output 1 (STAT1)
FIGURE 3-1:
Voltage Divider Example.
STAT1 is an open-drain logic output for connection to an LED for charge status indication. Alternatively, a pull-up resistor can be applied for interfacing to a host microcontroller. Refer to Table 5-1 for a summary of the status output during a charge cycle.
3.4
Input Source Type Selection (SEL)
3.11
Charge Status Output 2 (STAT2)
The input source type selection (SEL) pin is used to select input power source for input current limit control feature. With the SEL input High, the MCP73871 device is designed to provide a typical 1.65A to system power and charge Li-Ion battery from a regular 5V wall adapter. The MCP73871 device limits the input current up to 1.8A. When SEL active Low, the input source is designed to provide system power and Li-Ion battery charging from a USB Port input while adhering to the current limits governed by the USB specification.
STAT2 is an open-drain logic output for connection to an LED for charge status indication. Alternatively, a pull-up resistor can be applied for interfacing to a host microcontroller. Refer to Table 5-1 for a summary of the status output during a charge cycle.
3.12
Power-Good (PG)
3.5
Battery Management 0V Reference (VSS)
Connect to negative terminal of battery, system load and input supply.
3.6
Battery Charge Control Output (VBAT)
The power-good (PG) is an open-drain logic output for input power supply indication. The PG output is low whenever the input to the MCP73871 device is above the UVLO threshold and greater than the battery voltage. The PG output can be used as an indication to the user via an illuminated LED or to the system via a pull-up resistor for interfacing to a host microcontroller that an input source other than the battery is supplying power. Refer to Table 5-1 for a summary of the status output during a charge cycle.
3.13
Low Battery Output (LBO)
Connect to positive terminal of Li-Ion / Li-Polymer batteries. Bypass to VSS with a minimum of 4.7 F to ensure loop stability when the battery is disconnected.
3.7
Battery Voltage Sense (VBAT_SENSE)
Connect to positive terminal of battery. A precision internal voltage sense regulates the final voltage on this pin to VREG.
STAT1 also serves as low battery output (LBO) if the selected MCP73871 is equipped with this feature. It reminds the system or end user when the Li-Ion battery voltage level is low. The LBO feature enables when the system is running from the Li-Ion batteries. The LBO indicator can be used as an indication to the user via lit up LED or to the system via a pull-up resistor for interfacing to a host microcontroller that an input source other than the battery is supplying power. Refer to Table 5-1 for a summary of the status output during a charge cycle.
(c) 2009 Microchip Technology Inc.
DS22090B-page 16
MCP73871
3.14 Timer Enable (TE) 3.16 Charge Enable (CE)
The timer enable (TE) feature is used to enable or disable the internal timer. A low signal on this pin enables the internal timer and a high signal disables the internal timer. The TE input can be used to disable the timer when the system load is substantially limiting the available supply current to charge the battery. The TE input is compatible with 1.8V logic. Note: The built-in safety timer is available for the following options: 4 HR, 6 HR and 8 HR. With the CE input Low, the Li-Ion battery charger feature of the MCP73871 will be disabled. The charger feature is enabled when CE is active High. Allowing the CE pin to float during the charge cycle may cause system instability. The CE input is compatible with 1.8V logic. Refer to Section 6.0 "Applications" for various applications in designing with CE features.
3.17
Exposed Thermal Pad (EP)
3.15
Battery Temperature Monitor (THERM)
There is an internal electrical connection between the Exposed Thermal Pad (EP) and the VSS pin; they must be connected to the same potential.
The MCP73871 device continuously monitor battery temperature during a charge cycle by measuring the voltage between the THERM and VSS pins. An internal 50 A current source provides the bias for most common 10 k negative-temperature coefficient thermistors (NTC). The MCP73871 device compares the voltage at the THERM pin to factory set thresholds of 1.24V and 0.25V, typically. Once a voltage outside the thresholds is detected during a charge cycle, the MCP73871 device immediately suspends the charge cycle. The charge cycle resumes when the voltage at the THERM pin returns to the normal range. The charge temperature window can be set by placing fixed value resistors in series-parallel with a thermistor. Refer to Section 6.0 "Applications" for calculations of resistance values.
(c) 2009 Microchip Technology Inc.
DS22090B-page 17
MCP73871
NOTES:
DS22090B-page 18
(c) 2009 Microchip Technology Inc.
MCP73871
4.0 DEVICE OVERVIEW
The MCP73871 device is a simple, but fully integrated linear charge management controllers with system load sharing feature. Figure 4-1 depicts the operational flow algorithm.
SHUTDOWN MODE * VDD < VUVLO VDD < VBAT STAT1 = Hi-Z STAT2 = Hi-Z PG = Hi-Z
* Continuously Monitored
STANDBY MODE * VBAT > (VREG +100 mV) CE = LOW STAT1 = Hi-Z STAT2 = Hi-Z PG = LOW VBAT < VPTH PRECONDITIONING MODE Charge Current = IPREG STAT1 = LOW STAT2 = Hi-Z PG = LOW Timer Reset VBAT > VPTH TEMPERATURE FAULT No Charge Current STAT1 = LOW STAT2 = LOW PG = LOW Timer Suspended FAST CHARGE MODE Charge Current = IREG STAT1 = LOW STAT2 = Hi-Z PG = LOW Timer Enabled VBAT > VPTH
LBO * VIN < VBAT STAT1 = LOW STAT2 = Hi-Z PG = Hi-Z
Timer Expired
TIMER FAULT No Charge Current STAT1 = LOW STAT2 = LOW PG = LOW Timer Reset
CONSTANT VOLTAGE MODE Charge Voltage = VREG STAT1 = LOW STAT2 = Hi-Z PG = LOW IBAT < ITERM Timer Expired CHARGE COMPLETE MODE No Charge Current STAT1 = Hi-Z STAT2 = LOW PG = LOW Timer Reset
FIGURE 4-1:
MCP73871 Device Flow Chart.
(c) 2009 Microchip Technology Inc.
DS22090B-page 19
MCP73871
4.1 UnderVoltage Lockout (UVLO) 4.4 Preconditioning
An internal undervoltage lockout (UVLO) circuit monitors the input voltage and keeps the charger in shutdown mode until the input supply rises above the UVLO threshold. In the event a battery is present when the input power is applied, the input supply must rise approximately 100 mV above the battery voltage before the MCP73871 device become operational. The UVLO circuit places the device in shutdown mode if the input supply falls to approximately 100 mV of the battery voltage. The UVLO circuit is always active. At any time, the input supply is below the UVLO threshold or approximately 100 mV of the voltage at the VBAT pin, the MCP73871 device is placed in a shutdown mode. During any UVLO condition, the battery reverse discharge current shall be less than 2 A. If the voltage at the VBAT pin is less than the preconditioning threshold, the MCP73871 device enters a preconditioning mode. The preconditioning threshold is factory set. Refer to Section 1.0 "Electrical Characteristics" for preconditioning threshold options. In this mode, the MCP73871 device supplies 10% of the fast charge current (established with the value of the resistor connected to the PROG1 pin) to the battery. When the voltage at the VBAT pin rises above the preconditioning threshold, the MCP73871 device enters the constant current (fast charge) mode.
4.5
Constant Current Mode - Fast Charge
4.2
System Load Sharing
The system load sharing feature gives the system priority on input power, allowing the system to power-up with deeply depleted battery packs. With the SEL input active Low, the MCP73871 device is designed to provide system power and Li-Ion battery charging from a USB input while adhering to the current limits governed by the USB specification. With the SEL input active High, the MCP73871 device limits the total supply current to 1.8A (system power and charge current combined).
During the constant current mode, the programmed charge current is supplied to the battery or load. The charge current is established using a single resistor from PROG1 to VSS. The program resistor and the charge current are calculated using the following equation:
EQUATION 4-1:
1000VI REG = ------------------R PROG1 = = kilo-ohms (k) milliampere (mA)
Where: RPROG IREG
IN
System Power FET
Direction Control 0.2 Ideal Diode, Synchronous Switch OUT
Constant current mode is maintained until the voltage at the VBAT pin reaches the regulation voltage, VREG. When constant current mode is invoked, the internal timer is reset.
Current Limit Charge Control
0.2
4.5.1
TIMER EXPIRED DURING CONSTANT CURRENT - FAST CHARGE MODE
VBAT Charge FET Direction Control
FIGURE 4-2: Diagram.
System Load Sharing
If the internal timer expires before the recharge voltage threshold is reached, a timer fault is indicated and the charge cycle terminates. The MCP73871 device remains in this condition until the battery is removed. If the battery is removed, the MCP73871 device enters the Stand-by mode where it remains until a battery is reinserted.
4.3
Charge Qualification
4.6
Constant Voltage Mode
For a charge cycle to begin, all UVLO conditions must be met and a battery or output load must be present. A charge current programming resistor must be connected from PROG1 to VSS when SEL = High. When SEL = Low, PROG2 needs to tie to High or Low for proper operation.
When the voltage at the VBAT pin reaches the regulation voltage, VREG, constant voltage regulation begins. The regulation voltage is factory set to 4.10V or 4.20V with a tolerance of 0.5%.
DS22090B-page 20
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MCP73871
4.7 Charge Termination 4.9 Thermal Regulation
The charge cycle is terminated when, during constant voltage mode, the average charge current diminishes below a threshold established with the value of a resistor connected from PROG3 to VSS or internal timer has expired. A 1 ms filter time on the termination comparator ensures that transient load conditions do not result in premature charge cycle termination. The timer period is factory set and can be disabled. Refer to Section 1.0 "Electrical Characteristics" for timer period options. The program resistor and the charge current are calculated using the following equation: The MCP73871 device limits the charge current based on the die temperature. The thermal regulation optimizes the charge cycle time while maintaining device reliability. Figure 4-3 depicts the thermal regulation for the MCP73871 device. Refer to Section 1.0 "Electrical Characteristics" for thermal package resistances and Section 6.1.1.2 "Thermal Considerations" for calculating power dissipation.
.
1200 Charge Current (mA) 1000 800 600 400 200 0 25 50 75 100 125 150 Ambient Temperature (C)
VDD = 5.2V RPROG = 1 k
EQUATION 4-2:
I TERMINATION Where: RPROG IREG = = 1000V= ------------------R PROG3
kilo-ohms (k) milliampere (mA)
The charge current is latched off and the MCP73871 device enters a charge complete mode. The recommended PROG3 resistor values are between 5 k and 100 k.
FIGURE 4-3:
Thermal Regulation
4.10
Thermal Shutdown
4.8
Automatic Recharge
The MCP73871 device continuously monitors the voltage at the VBAT pin in the charge complete mode. If the voltage drops below the recharge threshold, another charge cycle begins and current is once again supplied to the battery or load. The recharge threshold is factory set. Refer to Section 1.0 "Electrical Characteristics" for recharge threshold options. Note: Charge termination and automatic recharge features avoid constant charging Li-Ion batteries to prolong life of Li-Ion batteries while keeping their capacity at healthy level.
The MCP73871 device suspends charge if the die temperature exceeds 150C. Charging will resume when the die temperature has cooled by approximately 10C. The thermal shutdown is a secondary safety feature in the event that there is a failure within the thermal regulation circuitry.
4.11
Temperature Qualification
The MCP73871 device continuously monitor battery temperature during a charge cycle by measuring the voltage between the THERM and VSS pins. An internal 50 A current source provides the bias for most common 10 k negative-temperature coefficient thermistors (NTC). The MCP73871 device compares the voltage at the THERM pin to factory set thresholds of 1.24V and 0.25V, typically. Once a voltage outside the thresholds is detected during a charge cycle, the MCP73871 device immediately suspends the charge cycle. The MCP73871 device suspends charge by turning off the charge pass transistor and holding the timer value. The charge cycle resumes when the voltage at the THERM pin returns to the normal range.
(c) 2009 Microchip Technology Inc.
DS22090B-page 21
MCP73871
4.12 Voltage Proportional Charge Control (VPCC) 4.13 Input Current Limit Control (ICLC)
If the input current threshold is reached, then the battery charging current is reduced. The ICLC tries to reach a steady-state condition where the system load has priority and the battery is charged with the remaining current. No active control limits the current to the system. Therefore, if the system demands more current than the input can provide or the input ICLC is reached, the ideal diode will become forward biased and the battery is able to supplement the input current to the system load. The ICLC sustains the system load as its highest priority. This is done by reducing the non-critical charge current while adhering to the current limits governed by the USB specification or the maximum ac-dc adapter current supported. Further demand from the system is supported by the battery, if possible.
700 600 500 400 300 200 100 0 -100 -200 0 100 200 300 400 500 600 700 Load Current (mA)
Ideal Diode
Input Current Battery Current Load Current
If the voltage on the IN pin drops to a preset value, determined by the threshold established at the VPCC input, due to a limited amount of input current or input source impedance, then the battery charging current is reduced. The VPCC control tries to reach a steady-state condition where the system load has priority and the battery is charged with the remaining current. Therefore, if the system demands more current than the input can provide, the ideal diode will become forward biased and the battery is able to supplement the input current to the system load. The VPCC sustains the system load as its highest priority. It does this by reducing the noncritical charge current while maintaining the maximum power output of the adapter. Further demand from the system is supported by the battery, if possible. The VPCC feature functions identically for USB port or ac-dc adapter inputs. This feature can be disabled by connecting the VPCC to IN pin.
FIGURE 4-4: USB Port.
Current (mA)
Input Current Limit Control -
DS22090B-page 22
(c) 2009 Microchip Technology Inc.
MCP73871
5.0
5.1
5.1.1
DETAILED DESCRIPTION
Analog Circuitry
LOAD SHARING AND LI-ION BATTERY MANAGEMENT INPUT SUPPLY (VIN)
1.24V and 0.25V, typically. Once a voltage outside the thresholds is detected during a charge cycle, the MCP73871 device immediately suspends the charge cycle. The MCP73871 device suspends charge by turning off the pass transistor and holding the timer value. The charge cycle resumes when the voltage at the THERM pin returns to the normal range. If temperature monitoring is not required, place a standard 10 k resistor from THERM to VSS.
The VIN input is the input supply to the MCP73871 device. The MCP73871 device can be supplied by either AC Adapter (VAC) or USB Port (VUSB) with SEL pin. The MCP73871 device automatically powers the system with the Li-Ion battery when the VIN input is not present.
5.2
5.2.1
Digital Circuitry
STATUS INDICATORS AND POWER-GOOD (PG)
5.1.2
FAST CHARGE CURRENT REGULATION SET (PROG1)
For the MCP73871 device, the charge current regulation can be scaled by placing a programming resistor (RPROG1) from the PROG1 pin to VSS. The program resistor and the charge current are calculated using the following equation:
The charge status outputs have two different states: Low (L), and High Impedance (Hi-Z). The charge status outputs can be used to illuminate LEDs. Optionally, the charge status outputs can be used as an interface to a host microcontroller. Table 5-1 summarizes the state of the status outputs during a charge cycle.
EQUATION 5-1:
I REG Where: RPROG IREG = = kilo-ohms (k) milliampere (mA) 1000V= ------------------R PROG1
TABLE 5-1:
STATUS OUTPUTS
STAT1 Hi-Z Hi-Z L L L Hi-Z L L L Hi-Z Hi-Z STAT2 Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z L L L Hi-Z Hi-Z Hi-Z PG Hi-Z L L L L L L L Hi-Z L Hi-Z
CHARGE CYCLE STATE Shutdown (VDD = VBAT) Shutdown (VDD = IN) Preconditioning Constant Current Constant Voltage Charge Complete - Standby Temperature Fault Timer Fault Low Battery Output No Battery Present No Input Power Present
The fast charge current is set for maximum charge current from ac-dc adapter and USB port. The preconditioning current is 10% (0.1C) to the fast charge current.
5.1.3
BATTERY CHARGE CONTROL OUTPUT (VBAT)
The battery charge control output is the drain terminal of an internal P-channel MOSFET. The MCP73871 device provides constant current and voltage regulation to the battery pack by controlling this MOSFET in the linear region. The battery charge control output should be connected to the positive terminal of the battery pack.
5.2.2
AC-DC ADAPTER AND USB PORT POWER SOURCE REGULATION SELECT (SEL)
5.1.4
TEMPERATURE QUALIFICATION (THERM)
The MCP73871 device continuously monitors battery temperature during a charge cycle by measuring the voltage between the THERM and VSS pins. An internal 50 A current source provides the bias for most common 10 k negative-temperature coefficient (NTC) or positive-temperature coefficient (PTC) thermistors.The current source is controlled, avoiding measurement sensitivity to fluctuations in the supply voltage (VDD). The MCP73871 device compares the voltage at the THERM pin to factory set thresholds of
With the SEL input Low, the MCP73871 device is designed to provide system power and Li-Ion battery charging from a USB input while adhering to the current limits governed by the USB specification. The host microcontroller has the option selecting either a 100 mA (L) or a 500 mA (H) current limit based on the PROG2 input. With the SEL input High, the MCP73871 device limits the input current to 1.8A. The programmed charge current is established using a single resistor from PROG1 to VSS when driving SEL High.
(c) 2009 Microchip Technology Inc.
DS22090B-page 23
MCP73871
5.2.3 USB PORT CURRENT REGULATION SELECT (PROG2) 5.2.5 TIMER ENABLE (TE) OPTION
Driving the PROG2 input to a logic Low selects the low USB port source current setting (maximum 100 mA). Driving the PROG2 input to a logic High selects the high USB port source current setting (Maximum 500 mA). The timer enable (TE) input option is used to enable or disable the internal timer. A low signal on this pin enables the internal timer and a high signal disables the internal timer. The TE input can be used to disable the timer when the charger is supplying current to charge the battery and power the system load. The TE input is compatible with 1.8V logic.
5.2.4
POWER-GOOD (PG)
The power-good (PG) option is a pseudo open-drain output. The PG output can sink current, but not source current. However, there is a diode path back to the input, and as such, the output should only be pulled up to the input. The PG output is low whenever the input to the MCP73871 device is above the UVLO threshold and greater than the battery voltage. The PG output can be used as an indication to the system that an input source other than the battery is supplying power.
DS22090B-page 24
(c) 2009 Microchip Technology Inc.
MCP73871
6.0 APPLICATIONS
The MCP73871 device is designed to operate in conjunction with a host microcontroller or in stand-alone applications. The MCP73871 device provides the preferred charge algorithm for Lithium-Ion and Lithium-Polymer cells Constant-current followed by Constant-voltage. Figure 6-1 depicts a typical stand-alone MCP73871 application circuit, while Figures 6-2 and 6-3 depict the accompanying charge profile.
MCP73871 Device Typical Application
5V AC-DC Adapter or USB Port 10 F
18, 19 470
IN
OUT VBAT
1, 20 4.7 F
System Load
6
PG
14, 15, 16 4.7 F
470 470 330 k
7 STAT2 8 STAT1 LBO VPCC SEL 4 PROG2 TE CE PROG3 THERM 5
NTC 10 k
2 3 110 k Low Low Low Low Hi Hi 9 Hi 17 Hi
PROG1
13
RPROG1
Single-Cell Li-Ion Battery
12 RPROG3
VSS 10, 11, EP
FIGURE 6-1:
4.5 4 Charge Voltage (V) 3.5 3 2.5 2 1.5 1 0.5 0 0 10 20
MCP73871Typical Stand-Alone Application Circuit with VPCC.
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 4.5 4 Charge Current (A) Charge Voltage (V) 3.5 3 2.5 2 1.5 1 0.5 0 0 0.2 0.4 0.6 0.8 1 Time (Minute)
Preconditioning Fast Charge (Constant Current) Preconditioning Threshold Voltage
MCP73871 VDD = 5.2V RPROG1 = 1 k RPROG3 = 25 k
MCP73871 VDD = 5.2V RPROG1 = 1 k RPROG3 = 25 k
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0
30
40
50
60
70
80
Time (Minute)
FIGURE 6-2: Typical Charge Profile (1000 mAh Battery).
FIGURE 6-3: Typical Charge Profile in Preconditioning (1000 mAh Battery).
(c) 2009 Microchip Technology Inc.
DS22090B-page 25
Charge Current (A)
MCP73871
6.1 Application Circuit Design
Due to the low efficiency of linear charging, the most important factors are thermal design and cost, which are a direct function of the input voltage, output current and thermal impedance between the battery charger and the ambient cooling air. The worst-case situation is when the device has transitioned from the Preconditioning mode to the Constant Current mode. In this situation, the battery charger has to dissipate the maximum power. A trade-off must be made between the charge current, cost and thermal requirements of the charger. This power dissipation with the battery charger in the QFN-20 package will cause thermal regulation to be entered as depicted. Alternatively, the 4 mm x 4 mm DFN package could be utilized to reduce heat by adding vias on the exposed pad.
6.1.1.3
External Capacitors
6.1.1
COMPONENT SELECTION
Selection of the external components in Figure 6-1 is crucial to the integrity and reliability of the charging system. The following discussion is intended as a guide for the component selection process.
The MCP73871 device is stable with or without a battery load. In order to maintain good AC stability in the Constant Voltage mode, a minimum capacitance of 4.7 F is recommended to bypass the VBAT pin to VSS. This capacitance provides compensation when there is no battery load. In addition, the battery and interconnections appear inductive at high frequencies. These elements are in the control feedback loop during Constant Voltage mode. Therefore, the bypass capacitance may be necessary to compensate for the inductive nature of the battery pack. Virtually any good quality output filter capacitor can be used, independent of the capacitor's minimum Effective Series Resistance (ESR) value. The actual value of the capacitor (and its associated ESR) depends on the output load current. A 4.7 F ceramic, tantalum or aluminum electrolytic capacitor at the output is usually sufficient to ensure stability for charge currents up to a 1000 mA.
6.1.1.1
Charge Current
The preferred fast charge current for Lithium-Ion cells should always follow references and guidances from battery manufacturers. For example, a 1000 mAh battery pack has a preferred fast charge current of 0.7C. Charging at 700 mA provides the shortest charge cycle times without degradation to the battery pack performance or life.
6.1.1.4
Reverse-Blocking Protection
6.1.1.2
Thermal Considerations
The worst-case power dissipation in the battery charger occurs when the input voltage is at the maximum and the device has transitioned from the Preconditioning mode to the Constant-current mode. In this case, the power dissipation is:
The MCP73871 device provides protection from a faulted or shorted input. Without the protection, a faulted or shorted input would discharge the battery pack through the body diode of the internal pass transistor.
6.1.1.5
Temperature Monitoring
EQUATION 6-1:
PowerDissipation = ( V DDMAX - V PTHMIN ) x I REGMAX
Where: VDDMAX IREGMAX VPTHMIN = = = the maximum input voltage the maximum fast charge current the minimum transition threshold voltage
The charge temperature window can be set by placing fixed value resistors in series-parallel with a thermistor. The resistance values of RT1 and RT2 can be calculated with the following equations in order to set the temperature window of interest. For NTC thermistors:
EQUATION 6-2:
R T2 x R COLD 24k = R T1 + -------------------------------R T2 + R COLD R T2 x R HOT 5k = R T1 + ---------------------------R T2 + R HOT = = = = the fixed series resistance the fixed parallel resistance the thermistor resistance at the lower temperature of interest the thermistor resistance at the upper temperature of interest
For example, power dissipation with a 5V, 10% input voltage source and 500 mA, 10% fast charge current is: Where:
EXAMPLE 6-1:
PowerDissipation = ( 5.5V - 2.7V ) x 550mA = 1.54W
RT1 RT2 RCOLD RHOT
DS22090B-page 26
(c) 2009 Microchip Technology Inc.
MCP73871
For example, by utilizing a 10 k at 25C NTC thermistor with a sensitivity index, , of 3892, the charge temperature range can be set to 0C - 50C by placing a 1.54 k resistor in series (RT1), and a 69.8 k resistor in parallel (RT2) with the thermistor.
6.2
PCB Layout Issues
For optimum voltage regulation, place the battery pack as close as possible to the device's VBAT and VSS pins, recommended to minimize voltage drops along the high current-carrying PCB traces. If the PCB layout is used as a heatsink, adding many vias in the heatsink pad can help conduct more heat to the backplane of the PCB, thus reducing the maximum junction temperature.
6.1.1.6
Charge Status Interface
A status output provides information on the state of charge. The output can be used to illuminate external LEDs or interface to a host microcontroller. Refer to Table 5-1 for a summary of the state of the status output during a charge cycle.
6.1.1.7
System Load Current
The preferred discharge current for Lithium-Ion cells should always follow references and guidance from battery manufacturers. Due to the safety concerns when using Lithium-Ion batteries and power dissipation of linear solutions, the system load when design with the MCP73871 device is recommended to be less than 1A or the maximum discharge rate of the selected Lithium-Ion cell. Whichever is smaller is recommended. The idea diode between VBAT and OUT is designed to drive a maximum current up to 2A. The built-in thermal shutdown protection may turn the MCP73871 device off with high current.
(c) 2009 Microchip Technology Inc.
DS22090B-page 27
MCP73871
NOTES:
DS22090B-page 28
(c) 2009 Microchip Technology Inc.
MCP73871
7.0
7.1
PACKAGING
Package Marking Information
20-Lead QFN
XXXXX XXXXXX XXXXXX YWWNNN Part Number * Marking Code Part Number * Marking Code 1AA 1CA 1CC 2AA 2CA 2CC 3CA 3CC 4CA 4CC
Example:
73871 1AA e3 I/ML^^ 919256
MCP73871-1AAI/ML 1AA MCP73871T-1AAI/ML MCP73871-1CAI/ML 1CA MCP73871T-1CAI/ML MCP73871-1CCI/ML 1CC MCP73871T-1CCI/ML MCP73871-2AAI/ML 2AA MCP73871T-2AAI/ML MCP73871-2CAI/ML 2CA MCP73871T-2CAI/ML MCP73871-2CCI/ML 2CC MCP73871T-2CCI/ML MCP73871-3CAI/ML 3CA MCP73871T-3CAI/ML MCP73871-3CCI/ML 3CC MCP73871T-3CCI/ML MCP73871-4CAI/ML 4CA MCP73871T-4CAI/ML MCP73871-4CCI/ML 4CC MCP73871T-4CCI/ML * Consult Factory for Alternative Device Options.
Legend: XX...X Y YY WW NNN
e3
* Note:
Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week `01') Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package.
In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information.
(c) 2009 Microchip Technology Inc.
DS22090B-page 29
MCP73871
/HDG 3ODVWLF 4XDG )ODW 1R /HDG 3DFNDJH 0/ [ [
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DS22090B-page 30
(c) 2009 Microchip Technology Inc.
MCP73871
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(c) 2009 Microchip Technology Inc.
DS22090B-page 31
MCP73871
NOTES:
DS22090B-page 32
(c) 2009 Microchip Technology Inc.
MCP73871
APPENDIX A: REVISION HISTORY
Revision B (May 2009)
The following is the list of modifications: 1. 2. 3. 4. Updated the QFN-20 package drawing. Updated Equation 4-1. Updated Section 4.7 "Charge Termination" and Equation 4-2. Updated Equation 5-1.
Revision A (July 2008)
* Original Release of this Document.
(c) 2009 Microchip Technology Inc.
DS22090B-page 33
MCP73871
NOTES:
DS22090B-page 34
(c) 2009 Microchip Technology Inc.
MCP73871
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. Device XX X/ XX Examples: * *
a) MCP73871-1AAI/ML: 4.10V PPM Battery Charger, 20LD QFN pkg. 4.10V, PPM Battery Charger, 20LD QFN pkg. 4.10V, PPM Battery Charger, 20LD QFN pkg.
4.20V, PPM Battery Charger, 20LD QFN
Output Temp. Package Options*
b)
Device: MCP73871: USB/AC Battery Charger with PPM MCP73871T: USB/AC Battery Charger with PPM (Tape and Reel)
MCP73871-1CAI/ML:
c)
MCP73871-1CCI/ML:
Output Options * *
* Refer to table below for different operational options. * * Consult Factory for Alternative Device Options.
d)
MCP73871-2AAI/ML:
Temperature:
I
= -40C to +85C
e)
MCP73871-2CAI/ML:
Package Type:
ML = Plastic Quad Flat No Lead (QFN) (4x4x0.9 mm Body), 20-lead
f)
MCP73871-2CCI/ML:
g)
MCP73871-3CAI/ML:
h)
MCP73871-3CCI/ML:
pkg. 4.20V PPM Battery Charger, 20LD QFN pkg. 4.20V PPM Battery Charger, 20LD QFN pkg. 4.35V PPM Battery Charger, 20LD QFN pkg. 4.35V PPM Battery Charger, 20LD QFN pkg.
* * Consult Factory for Alternative Device Options
* Operational Output Options
Output Options 1AA 1CA 1CC 2AA 2CA 2CC 3CA 3CC 4CA 4CC VREG 4.10V 4.10V 4.10V 4.20V 4.20V 4.20V 4.35V 4.35V 4.40V 4.40V Safety Timer Duration (Hours) Disable 6 6 Disable 6 6 6 6 6 6 LBO Voltage Threshold (V) Disabled Disabled 3.1 Disabled Disabled 3.1 Disabled 3.1 Disabled 3.1
* * Consult Factory for Alternative Device Options.
(c) 2009 Microchip Technology Inc.
DS22090B-page 35
MCP73871
NOTES:
DS22090B-page 36
(c) 2009 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices: * * Microchip products meet the specification contained in their particular Microchip Data Sheet. Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. Microchip is willing to work with the customer who is concerned about the integrity of their code. Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as "unbreakable."
*
* *
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip's code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.
Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, rfPIC, SmartShunt and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Hampshire, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, nanoWatt XLP, PICkit, PICDEM, PICDEM.net, PICtail, PIC32 logo, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. (c) 2009, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company's quality system processes and procedures are for its PIC(R) MCUs and dsPIC(R) DSCs, KEELOQ(R) code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip's quality system for the design and manufacture of development systems is ISO 9001:2000 certified.
(c) 2009 Microchip Technology Inc.
DS22090B-page 37
WORLDWIDE SALES AND SERVICE
AMERICAS
Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://support.microchip.com Web Address: www.microchip.com Atlanta Duluth, GA Tel: 678-957-9614 Fax: 678-957-1455 Boston Westborough, MA Tel: 774-760-0087 Fax: 774-760-0088 Chicago Itasca, IL Tel: 630-285-0071 Fax: 630-285-0075 Cleveland Independence, OH Tel: 216-447-0464 Fax: 216-447-0643 Dallas Addison, TX Tel: 972-818-7423 Fax: 972-818-2924 Detroit Farmington Hills, MI Tel: 248-538-2250 Fax: 248-538-2260 Kokomo Kokomo, IN Tel: 765-864-8360 Fax: 765-864-8387 Los Angeles Mission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608 Santa Clara Santa Clara, CA Tel: 408-961-6444 Fax: 408-961-6445 Toronto Mississauga, Ontario, Canada Tel: 905-673-0699 Fax: 905-673-6509
ASIA/PACIFIC
Asia Pacific Office Suites 3707-14, 37th Floor Tower 6, The Gateway Harbour City, Kowloon Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431 Australia - Sydney Tel: 61-2-9868-6733 Fax: 61-2-9868-6755 China - Beijing Tel: 86-10-8528-2100 Fax: 86-10-8528-2104 China - Chengdu Tel: 86-28-8665-5511 Fax: 86-28-8665-7889 China - Hong Kong SAR Tel: 852-2401-1200 Fax: 852-2401-3431 China - Nanjing Tel: 86-25-8473-2460 Fax: 86-25-8473-2470 China - Qingdao Tel: 86-532-8502-7355 Fax: 86-532-8502-7205 China - Shanghai Tel: 86-21-5407-5533 Fax: 86-21-5407-5066 China - Shenyang Tel: 86-24-2334-2829 Fax: 86-24-2334-2393 China - Shenzhen Tel: 86-755-8203-2660 Fax: 86-755-8203-1760 China - Wuhan Tel: 86-27-5980-5300 Fax: 86-27-5980-5118 China - Xiamen Tel: 86-592-2388138 Fax: 86-592-2388130 China - Xian Tel: 86-29-8833-7252 Fax: 86-29-8833-7256 China - Zhuhai Tel: 86-756-3210040 Fax: 86-756-3210049
ASIA/PACIFIC
India - Bangalore Tel: 91-80-3090-4444 Fax: 91-80-3090-4080 India - New Delhi Tel: 91-11-4160-8631 Fax: 91-11-4160-8632 India - Pune Tel: 91-20-2566-1512 Fax: 91-20-2566-1513 Japan - Yokohama Tel: 81-45-471- 6166 Fax: 81-45-471-6122 Korea - Daegu Tel: 82-53-744-4301 Fax: 82-53-744-4302 Korea - Seoul Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934 Malaysia - Kuala Lumpur Tel: 60-3-6201-9857 Fax: 60-3-6201-9859 Malaysia - Penang Tel: 60-4-227-8870 Fax: 60-4-227-4068 Philippines - Manila Tel: 63-2-634-9065 Fax: 63-2-634-9069 Singapore Tel: 65-6334-8870 Fax: 65-6334-8850 Taiwan - Hsin Chu Tel: 886-3-6578-300 Fax: 886-3-6578-370 Taiwan - Kaohsiung Tel: 886-7-536-4818 Fax: 886-7-536-4803 Taiwan - Taipei Tel: 886-2-2500-6610 Fax: 886-2-2508-0102 Thailand - Bangkok Tel: 66-2-694-1351 Fax: 66-2-694-1350
EUROPE
Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 France - Paris Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 Germany - Munich Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 Spain - Madrid Tel: 34-91-708-08-90 Fax: 34-91-708-08-91 UK - Wokingham Tel: 44-118-921-5869 Fax: 44-118-921-5820
03/26/09
DS22090B-page 38
(c) 2009 Microchip Technology Inc.

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