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19-2800; Rev 0; 4/03
Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications
General Description
The MAX1501 intelligent, constant-current, constantvoltage (CCCV), temperature-regulated battery charger charges a single lithium-ion (Li+) cell or three-cell NiMH/NiCd batteries. The device integrates the currentsense resistor, PMOS pass element, and thermalregulation circuitry, while eliminating the reverseblocking Schottky diode to create the simplest charging solution for hand-held equipment. The MAX1501 functions as a stand-alone charger to control the charging sequence from the prequalification state through fast charge, top-off, and charge termination for single-cell Li+ or three-cell NiMH/NiCd batteries. Alternatively, the MAX1501 collaborates with a host microprocessor to determine the best charging algorithm. Proprietary thermal-regulation circuitry limits the die temperature when fast charging or while exposed to high ambient temperatures, allowing maximum charging current without damaging the charger. The MAX1501 continually supplies a regulated output voltage under no-battery conditions, allowing battery changing. The device achieves high flexibility by providing an adjustable fast-charge current, top-off current, safety timer, and thermal-regulation setpoint. Other features include input power detection (ACOK) and input under-/ overvoltage protection. The MAX1501 provides activelow control inputs. The MAX1501 accepts a 4.5V to 13V supply, but disables charging when the input voltage exceeds 6.5V, preventing excessive power dissipation. The MAX1501 operates over the extended temperature range (-40C to +85C) and is available in a compact 16-pin thermally enhanced 5mm x 5mm thin QFN package with 0.8mm profile.
Features
o Stand-Alone or Microprocessor-Controlled (P) Linear 1-Cell Li+ or 3-Cell NiMH/NiCd Battery Charger o No FET, Reverse-Blocking Diode, or CurrentSense Resistor Required o 1.4A (max) Programmable Fast-Charge Current o +95C, +115C, and +135C Proprietary Programmable Die Temperature Regulation Control o 4.5V to 13V Input Voltage Range with Input Overvoltage (OVLO) Protection Above 6.5V o Programmable Top-Off Current Threshold: 10%, 20%, or 30% of the Fast-Charge Current o Charge-Current Monitor for Fuel Gauging o Programmable Safety Timer (3, 4.5, or 6 hours) o Input Power Detection Output (ACOK) and Charge Enable Input (CHGEN) o Automatic Recharge o Digital Soft-Start Limits Inrush Current o Charge Status Outputs for LEDs or P Interface
MAX1501
Ordering Information
PART MAX1501ETE TEMP RANGE -40C to +85C PIN-PACKAGE 16 Thin QFN
Typical Operating Circuit
INPUT 4.5V TO 13V IN
BATT
4.2V 1-CELL Li+ INP 10F
Applications
Cellular and Cordless Phones PDAs Digital Cameras and MP3 Players USB Appliances Charging Cradles and Docks BluetoothTM Equipment
1F
MAX1501
FULLI
GLED RLED TEMP TMAX SETI 2.8k GND
VL SELV MODE CHGEN VLOGIC ( 5.5V)
RPULLUP
ACOK
Pin Configuration appears at end of data sheet. Bluetooth is a trademark of Ericsson.
________________________________________________________________ Maxim Integrated Products
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
ABSOLUTE MAXIMUM RATINGS
IN, INP, RLED, GLED to GND ................................-0.3V to +14V IN to INP ................................................................-0.3V to +0.3V VL, BATT, SETI, ACOK, MODE, CHGEN, SELV, FULLI, TMAX, TEMP to GND ................................-0.3V to +6V VL to IN...................................................................-14V to +0.3V Continuous Power Dissipation (TA = +70C) 16-Pin 5mm 5mm Thin QFN (derate 21.3mW/C above +70C) .............................1702mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8k, CIN = 1F, CBATT = 10F, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER IN, INP Input Voltage IN, INP Input Operating Range VL Output Voltage ACOK Trip Point ACOK Sink Current Undervoltage Lockout Trip Point Overvoltage Lockout Trip Point IN Input Current 4.5V VIN 6.25V, IVL < 250A VIN - VBATT, rising VIN - VBATT, falling VIN - VBATT, hysteresis 4.5V VIN 6.25V, V ACOK = 0.6V VIN rising VIN falling Hysteresis VIN rising Li+, NiMH/NiCd, and no-battery modes Disable mode Off mode (VIN = 4V) VBATT = 4.3V BATT Input Current Leakage into Battery RMS Charge Current Li+ mode Battery Regulation Voltage NiMH/NiCd mode Output Regulation Voltage BATT Precharge Threshold Voltage Fast-Charge Current-Loop System Accuracy No-battery mode BATT rising RSETI = 2.8k RSETI = 1.75 k SELV = VL SELV = GND SELV = VL, VIN = VINP = 6V SELV = GND 4.166 4.067 4.85 4.4 3.700 2.675 460 736 4.2 4.1 4.95 4.5 4.0 2.8 500 800 VIN = 0 Disable mode VIN = VINP = 13V, VBATT = 0 Disable mode 45 3 2 6.25 75 4.05 3.9 4.125 4.025 100 6.50 5 1.5 6.75 8 3 0.25 80 10 6 5 1.4 4.234 4.133 5.05 4.6 4.234 2.925 540 864 V V mA V A A A mA 4.20 4.1 CONDITIONS MIN 0 4.50 2.7 40 30 3 70 55 15 A V mV V TYP MAX 13 6.25 3.3 100 85 mV UNITS V V V
2
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8k, CIN = 1F, CBATT = 10F, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Precharge Current System Accuracy Die Temperature Regulation Setpoint (Note 1) Current-Sense Amplifier Gain Internal Current-Sense Resistance Regulator Dropout Voltage Logic Input Low Voltage Logic Input High Voltage Internal Pulldown Resistance Internal Pullup Resistance Internal Bias Resistance Internal Bias Voltage RLED Output Low Current GLED Output Low Current GLED, RLED Output High Leakage Current Full-Battery Detection Current Threshold VIN - VBATT, NiMH/NiCd mode, VBATT = 4.3V, IBATT = 425mA CHGEN, MODE, 4.5V VIN 6.25V CHGEN, MODE, 4.5V VIN 6.25V CHGEN, MODE SELV FULLI, TEMP, TMAX FULLI, TEMP, TMAX V RLED = 1V V GLED = 1V V GLED = V RLED = VIN = VINP = 13V FULLI = GND % of fast-charge current Li+ mode NiMH/NiCd mode Charge-Timer Accuracy TMAX = GND Charge-Timer Duration TMAX = open TMAX = VL FULLI = VL FULLI = open SELV = VL SELV = GND VBATT Restart Threshold 5 15 25 3.9 3.8 3.9 -10 3 4.5 6 hrs 7 14 1.25 100 100 50 175 175 90 VVL/2 10 20 0.1 10 20 30 4.0 3.9 4.0 18 34 1 15 25 35 4.1 4.0 4.1 +10 % V % 400 400 200 CONDITIONS % of fast-charge current, VBATT = 2V TEMP = GND TEMP = open TEMP = VL IBATT to ISETI, precharge mode, VBATT = 2V IBATT to ISETI, fast-charge mode 0.70 0.95 MIN 5 TYP 10 95 115 135 1 1 84 190 350 0.52 1.30 1.05 mA/A m mV V V k k k V mA mA A
o
MAX1501
MAX 15
UNITS %
C
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
ELECTRICAL CHARACTERISTICS
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8k, CIN = 1F, CBATT = 10F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 2)
PARAMETER IN, INP Input Voltage IN, INP Input Operating Range VL Output Voltage ACOK Trip Point ACOK Sink Current Undervoltage Lockout Trip Point Overvoltage Lockout Trip Point IN Input Current Li+, NiMH/NiCd, and no-battery modes Disable mode VBATT = 4.3V BATT Input Current Leakage into Battery RMS Charge Current Li+ mode Battery Regulation Voltage NiMH/NiCd mode Output Regulation Voltage BATT Precharge Threshold Voltage Fast-Charge Current-Loop System Accuracy Precharge Current System Accuracy Current-Sense Amplifier Gain Regulator Dropout Voltage Logic Input Low Voltage Logic Input High Voltage Internal Pulldown Resistance Internal Pullup Resistance Internal Bias Resistance No-battery mode BATT rising RSETI = 2.8k RSETI = 1.75k % of fast-charge current, VBATT = 2V IBATT to ISETI, precharge mode, VBATT = 2V IBATT to ISETI, fast-charge mode VIN - VBATT, NiMH/NiCd mode, VBATT = 4.3V, IBATT = 425mA CHGEN, MODE, 4.5V < VIN < 6.25V CHGEN, MODE, 4.5V < VIN < 6.25V CHGEN, MODE SELV FULLI, TEMP, TMAX 1.3 100 100 50 400 400 200 SELV = VL SELV = GND SELV = VL SELV = GND 4.148 4.05 4.85 4.4 3.700 2.675 460 736 5 0.60 0.93 VIN = 0 Disable mode VIN = VINP = 13V, VBATT = 0 Disable mode 4.5V VIN 6.25V, IVL < 250A VIN - VBATT, rising VIN - VBATT, falling 4.5V VIN 6.25V, V ACOK = 0.6V VIN rising VIN falling CONDITIONS MIN 0 4.50 2.7 40 30 75 4.00 3.90 6.25 4.25 4.15 6.75 8 3 80 10 6 5 1.4 4.252 4.15 5.05 4.6 4.234 2.925 540 864 15 1.40 1.07 350 0.52 V V mA % mA/A mV V V k k k V A A A TYP MAX 13 6.25 3.3 100 85 UNITS V V V mV A V V mA
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VINP = 5V, VBATT = 3.5V, ACOK = GLED = RLED = TEMP = TMAX = FULLI = open, CHGEN = MODE = GND, RSETI = 2.8k, CIN = 1F, CBATT = 10F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 2)
PARAMETER RLED Output Low Current GLED Output Low Current GLED, RLED Output High Leakage Current Charge-Timer Accuracy V RLED = 1V V GLED = 1V V GLED = V RLED = VIN = VINP = 13V -10 CONDITIONS MIN 7 14 TYP MAX 18 34 1 +10 UNITS mA mA A %
MAX1501
Note 1: Temperature regulation setpoint variation is typically 9C. Note 2: Specifications to TA = -40C are guaranteed by design, not production tested.
Typical Operating Characteristics
(VIN = VINP = 5V, ACOK = RLED = GLED = TEMP = TMAX = FULLI = open, CBATT = 10F, CIN = 1F, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX1501 toc01
DISABLE-MODE SUPPLY CURRENT vs. INPUT VOLTAGE
MAX1501 toc02
CHARGE CURRENT vs. BATTERY VOLTAGE
Li+ MODE, RSETI = 2.7k, VIN = 5V, SELV = VL
MAX1501 toc03 MAX1501 toc06
5.0 4.5 4.0 SUPPLY CURRENT (mA) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0
DISABLE-MODE SUPPLY CURRENT (mA)
Li+ MODE OR NiMH/NiCd MODE, SELV = VL, IBATT = 0
2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0
600 550 CHARGE CURRENT (mA) 500 450 400 350 300 250 200 150 100 50 0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 INPUT VOLTAGE (V)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 INPUT VOLTAGE (V)
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 BATTERY VOLTAGE (V)
CHARGE CURRENT vs. BATTERY VOLTAGE
MAX1501 toc04
CHARGE CURRENT vs. INPUT VOLTAGE
Li+ MODE, SELV = VL, RSETI = 2.7k
MAX1501 toc05
CHARGE CURRENT vs. INPUT-VOLTAGE HEADROOM
600 550 CHARGE CURRENT (mA) 500 450 400 350 300 250 200 150 100 50 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 VIN - VBATT (V) NiMH/NiCd MODE, SELV = GND, RSETI = 2.7k, VBATT = 4.3V
600 550 500 450 400 350 300 250 200 150 100 50 0 0
NiMH/NiCd, RSETI = 2.7k, VIN = 5.5V, SELV = VL
600 550 CHARGE CURRENT (mA) 500 450 400 350 300 250 200 150 100 50 0
CHARGE CURRENT (mA)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 BATTERY VOLTAGE (V)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 INPUT VOLTAGE (V)
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
Typical Operating Characteristics (continued)
(VIN = VINP = 5V, ACOK = RLED = GLED = TEMP = TMAX = FULLI = open, CBATT = 10F, CIN = 1F, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1501 toc07
BATTERY REGULATION VOLTAGE vs. TEMPERATURE
Li+ MODE BATTERY REGULATION VOLTAGE (V) 4.20 4.18 4.16 4.14 4.12 4.10 4.08 SELV = GND SELV = VL
MAX1501 toc08
4.0 3.5 OUTPUT VOLTAGE (V) 3.0 2.5 2.0 1.5 1.0 0.5 0
NO BATTERY MODE IBATT = 0
4.22
0 1 2 3 4 5 6 7 8 9 10 11 12 13 INPUT VOLTAGE (V)
-40
-15
10
35
60
85
TEMPERATURE (C)
CHARGE CURRENT vs. AMBIENT TEMPERATURE
MAX1501 toc09
CHARGE CURRENT vs. AMBIENT TEMPERATURE
900 800 CHARGE CURRENT (mA) 700 600 500 400 300 200 100 0 Li+ MODE, TEMP = VL, VBATT = 3.6V, VIN = 6V, RSETI = 1.75k
MAX1501 toc10
600 580 560 CHARGE CURRENT (mA) 540 520 500 480 460 440 420 400 -40 -15 10 35 60 Li+ MODE, TEMP = VL, VBATT = 3.6V, VIN = 5V, RSETI = 2.7k
1000
85
-40
-15
10
35
60
85
AMBIENT TEMPERATURE (C)
AMBIENT TEMPERATURE (C)
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications
Pin Description
PIN 1 NAME INP FUNCTION High-Current Charger Input. Connect an AC adapter to INP and IN as close to the device as possible. INP provides charge current to the battery. INP draws current while the device is in shutdown mode. Low-Current Charger Input. Bypass IN to GND with a 1F ceramic capacitor. Connect IN to INP as close to the device as possible. IN powers the internal LDO and reference. IN draws current while the device is in shutdown mode. Ground. Connect the exposed paddle to GND. Current-Sense Transconductance Amplifier Output. Connect a resistor from SETI to GND to program the maximum charge current and to monitor the actual charge current. SETI pulls to GND during shutdown. Linear Regulator Output. Connect CHGEN, TEMP, TMAX, FULLI, and MODE to VL to program logic high. VL discharges to GND during shutdown. Maximum Charging-Time Select Input. TMAX sets the maximum charging time. Connect TMAX to GND to set the maximum charging time to 3 hours. Leave TMAX floating to set the maximum charging time to 4.5 hours. Connect TMAX to VL to set the maximum charging time to 6 hours. TMAX pulls to GND through a 50k resistor in shutdown. Top-Off-Current Select Input. FULLI sets the end-of-charge threshold as a percentage of the fast-charge current. Connect FULLI to GND to set the end-of-charge threshold to 10% of the fast-charge current. Connect FULLI to VL to set the end-of-charge threshold to 20% of the fast-charge current. Leave FULLI floating to set the end-of-charge threshold to 30% of the fast-charge current. FULLI pulls to GND through a 50k resistor in shutdown. Die Temperature Select Input. TEMP sets the die temperature regulation point for the thermal-control loop. Connect TEMP to GND to regulate the die temperature at +95C. Leave TEMP floating to regulate the die temperature at +115C. Connect TEMP to VL to regulate the die temperature at +135C. TEMP pulls to GND through a 50k resistor in shutdown. Mode Select Input. MODE and CHGEN together control charging functions (Table 1). An internal 175k pulldown resistor pulls MODE low. Charge Enable Input. CHGEN and MODE together control charging functions (Table 1). An internal 175k pulldown resistor pulls CHGEN low. Input Voltage Range Indicator. The open-drain ACOK output asserts low when 4.2V VIN 6.25V and VIN - VBATT 100mV. ACOK requires an external 100k pullup resistor. ACOK floats in shutdown. Battery Connection. Connect the positive terminal of the battery to BATT. BATT draws less than 5A during shutdown. Battery Voltage Selection Input. SELV sets the battery regulation voltage in Li+ and NiMH/NiCd modes (Table 2). For no-battery mode, the battery voltage defaults to 4.0V. An internal 175k resistor to VL pulls SELV high. Battery Charging Indicator. Connect the anode of a red LED to IN and the cathode to RLED. RLED asserts low when the input supply is present and the battery is charging, regardless of cell chemistry. RLED sinks 10mA. RLED goes high impedance in shutdown. Connect a pullup resistor to the P's I/O supply when interfacing with a P logic input. Full-Charge Indicator. Connect the anode of a green LED to IN and the cathode to GLED. GLED asserts low when the input supply is present and the battery has reached the top-off current threshold set by FULLI, regardless of cell chemistry. GLED sinks 20mA. GLED goes high impedance in shutdown. Connect a pullup resistor to the P's I/O supply when interfacing with a P logic input.
MAX1501
2 3, 13 4 5
IN GND SETI VL
6
TMAX
7
FULLI
8
TEMP
9 10 11 12
MODE CHGEN ACOK BATT
14
SELV
15
RLED
16
GLED
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
MAX1501
INP BATT
VREF CS OUTPUT DRIVER AND LOGIC
SETI TEMP REF
IREF IN SHUTDOWN UVLO VL VL
TEMPERATURE SENSOR
CHGEN
MODE REF OVLO ON ACOK RLED FULLI GLED OSC TMAX LOGIC TEMP SELV
GND
GND
Figure 1. Functional Diagram
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
OFF
ACOK = HIGH CHARGER OFF ACOK = LOW RLED = OFF GLED = OFF ACOK = (4.2V < VIN < 6.25V) AND (VIN - VBATT > 100mV)
ACOK = LOW CHGEN = LOW VBATT < 2.8V CHGEN = HIGH MODE = LOW
DISABLE
CHARGER OFF ACOK = LOW RLED = OFF GLED = OFF CHGEN = LOW
PREQUAL
10% SETI CURRENT ACOK = LOW RLED = ON GLED = OFF
NOBATT
(CURRENT LIMITED AND CHGEN = LOW THERMALLY PROTECTED) ACOK = LOW RLED = OFF GLED = OFF CHGEN = HIGH MODE = HIGH SOFT-START
SOFT-START
VBATT < 2.8V
FAST CHARGE
(THERMALLY PROTECTED) 100% SETI CURRENT ACOK = LOW RLED = ON GLED = OFF
TIME > TMAX
ICHG < ITOP-OFF
VBATT < 4V (Li+ MODE, SELV = VL, AND NiMH/NiCd MODE) VBATT < 3.9V (Li+ MODE, SELV = GND)
TOP OFF
(VOLTAGE LOOP) RLED = OFF GLED = ON
TIME > TMAX
DONE
CHARGER OFF RLED = OFF GLED = ON
Figure 2. Charge State Diagram
Detailed Description
Modes of Operation
CHGEN and MODE together set the operating modes of the MAX1501. Both inputs possess internal 175k pulldown resistors to GND. Table 1 describes the four operating modes of the MAX1501.
Table 1. Modes of Operation
MODE Li+ Charge Mode NiMH/NiCd Charge Mode Disable Mode No-Battery Mode CHGEN 0 0 1 1 MODE 0 1 0 1
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
Table 2. Battery Regulation Voltage
CHARGING MODE Li+ NiMH/NiCd SELV GND 4.1V 4.5V VL 4.2V 4.95V
The thermal-regulation loop limits the MAX1501 die temperature to the value selected by the TEMP input by reducing the charge current as necessary (see the Thermal-Regulation Selection section). This feature not only protects the MAX1501 from overheating, but also allows the charge current to be set higher without risking damage to the system. Set the top-off-current threshold with the three-state FULLI input (see the Top-Off-Current Selection section). RLED goes high impedance and GLED asserts low when the top-off-current threshold is reached. The MAX1501 automatically initiates recharging when the battery voltage drops below 95% of the voltage set by SELV.
Li+ Charge Mode
Connect CHGEN and MODE to GND to place the MAX1501 in Li+ charging mode. The Li+ charger consists of a voltage-control loop, a current-control loop, and a thermal-control loop. Connect SELV to GND to set the Li+ battery voltage to 4.1V. Connect SELV to VL to set the Li+ battery voltage to 4.2V (Table 2). The MAX1501 precharges the Li+ battery with 10% of the user-programmed fast-charge current at the start of a charge cycle. A soft-start algorithm ramps up the charging current (10% steps with 20ms duration per step) to the fast-charge current when the battery voltage reaches 2.8V. The MAX1501 enters constant-voltage mode and decreases the charge current when the BATT voltage reaches the selected regulation voltage (4.1V or 4.2V). Set the fast-charge current with a resistor between SETI and GND (see the Charge-Current Selection section).
NiMH/NiCd Charge Mode
Connect CHGEN to GND and MODE to VL to place the MAX1501 in NiMH/NiCd charging mode. The NiMH/NiCd battery charger consists of a current-control loop, a voltage-control loop, and a thermal-control loop. Connect SELV to GND to set the regulation voltage to 4.5V. Connect SELV to VL to set the regulation voltage to 4.95V (Table 2). When charging three NiMH/NiCd cells to 4.95V, VIN must be at least 5.25V and a P must be used to terminate the charge sequence.
REGULATION VOLTAGE
PREQUALIFICATION
FAST CHARGING
TOP-OFF
DONE
FAST-CHARGE CURRENT BATTERY CURRENT RLED TURNS OFF AND GLED TURNS ON WHEN CHARGE CURRENT DROPS TO VALUE SET BY FULLI (10%, 20%, OR 30% OF FASTCHARGE CURRENT). BATTERY VOLTAGE MINIMUM CHARGE VOLTAGE (2.8V) CHARGE TERMINATED 10% OF FAST-CHARGE CURRENT
tPREQUAL
tMAX
Figure 3. Li+ Charge Sequence 10 ______________________________________________________________________________________
Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications
Table 3. RLED and GLED Behavior
MODE STATE * 10% current-limited precharge * Current-limited charge * Voltage-limited charge before top-off * Temperature-limited charge before top-off * Voltage-limited charge after top-off * Safety timer expires Disable Mode No Battery Mode -- -- RLED GLED
MAX1501
Sinks 10mA
High impedance
Li+ Mode or NiMH/NiCd Mode
High impedance High impedance High impedance
Sinks 20mA High impedance High impedance
The MAX1501 precharges the NiMH/NiCd battery with 10% of the user-programmed fast-charge current at the start of a charge cycle. Precharge ends and fast charge begins when the battery voltage exceeds 2.8V. Set the fast-charge current with a resistor between SETI and GND (see the Charge-Current Selection section). The MAX1501 enters constant-voltage mode and decreases the charge current when the battery voltage reaches 4.5V. The thermal-regulation loop limits the MAX1501 die temperature to the value selected by the TEMP input by reducing the charge current as necessary (see the Thermal-Regulation Selection section). This feature protects the MAX1501 from overheating when supplying high charge currents, or while operating from high input voltages. Set the top-off-current threshold with the three-state FULLI input (see the Top-Off-Current Selection section). RLED goes high impedance and GLED asserts low when the top-off current threshold is reached. The MAX1501 automatically initiates recharging when the battery voltage drops below 4V.
resistor to an external supply voltage. The external supply voltage must be less than 5.5V.
RLED and GLED Indicators
RLED and GLED serve as visual indicators that power is applied as well as the charge status of a battery. RLED asserts low when a wall adapter is connected and a battery is charging, regardless of cell chemistry. GLED asserts low when power is applied and the battery is fully charged. Both outputs go high-impedance in shutdown. Connect the anode of each LED to IN, and the cathode to RLED or GLED. Table 3 summarizes the behavior of RLED and GLED under normal operating conditions. Connect pullup resistors to the P I/O supply when interfacing RLED and GLED with a P's logic inputs.
Soft-Start
A ten-step, soft-start algorithm activates when entering fast-charge mode. The charging current ramps up in 10% increments, 20ms per step, to the full charging current when VBATT exceeds 2.8V.
Applications Information
Charge-Current Selection
Program the charging current using an external resistor between SETI and GND. Set the charge-current resistor with the following equation: RSETI = 1000 x 1.4V IBATT
No-Battery Mode
Connect CHGEN and MODE to VL to place the MAX1501 in no-battery mode. An external load can be connected to BATT in this mode. VBATT regulates to 4V in no-battery mode, regardless of the state of SELV. The current-control loop, voltage-control loop, and thermal-control loop all function in no-battery mode. The loop gain of the voltage-control loop decreases to ensure stability with no battery present. Connect a 10F ceramic capacitor to BATT for stability. RLED and GLED are both high impedance in no-battery mode.
ACOK
The ACOK output asserts low when VIN is present, 4.2V VIN 6.25V, and VIN - VBATT > 100mV. The ACOK open-drain output requires an external 100k pullup
If VSETI = 1.4V, the current-control loop controls the battery charging. If VSETI < 1.4V, either the voltagecontrol loop or the thermal-control loop operates. Measure the charging current by monitoring VSETI and using the following equation: I VSETI = BATT x RSETI 1000
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Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
Thermal-Regulation Selection
Set the regulated die temperature of the MAX1501 with the TEMP three-level logic input. The MAX1501 reduces the charge current to limit the die temperature to the value set by TEMP. The MAX1501 operates normally while the thermal loop is active. An active thermal loop does not indicate a fault condition. TEMP allows the MAX1501 to maximize the charge current while providing protection against excessive power dissipation. Connect TEMP to GND to regulate the die temperature at +95C. Leave TEMP floating to regulate the die temperature at +115C. Connect TEMP to VL to regulate the die temperature at +135C. to 4.5 hours. Connect TMAX to VL to set the maximum charging time to 6 hours.
Capacitor Selection
Connect a ceramic capacitor from BATT to GND for proper stability. Use a 10F X5R ceramic capacitor for most applications. Connect IN and INP together and bypass to GND with a 1F ceramic capacitor. Use a larger input bypass capacitor for high input voltages or high charging currents to reduce supply noise.
Thermal Considerations
The MAX1501 is available in a thermally enhanced thin QFN package with exposed paddle. Connect the exposed paddle of the MAX1501 to a large copper ground plane to provide a thermal contact between the device and the circuit board. The exposed paddle transfers heat away from the device, allowing the MAX1501 to charge the battery with maximum current, while minimizing the increase in die temperature.
Top-Off-Current Selection
Set the top-off-current threshold in the Li+ and NiMH/NiCd charge modes with the FULLI three-level logic input. The top-off-current threshold determines when RLED turns off and GLED turns on, indicating the charge status of the battery. Connect FULLI to GND to set the top-off-current threshold to 10% of the fast-charge current. Connect FULLI to VL to set the top-off-current threshold to 20% of the fast-charge current. Leave FULLI floating to set the topoff-current threshold to 30% of the fast-charge current.
Application Circuits
Figure 4 shows the MAX1501 as a stand-alone Li+ battery charger. The 2.8k resistor connected to SETI sets a charging current of 500mA. Figure 5 shows the MAX1501 as a P-based Li+ battery charger. Drive CHGEN low to charge the battery. Drive CHGEN high to disable the charger. Connect a 100k pullup resistor from ACOK to the logic supply voltage of the P to detect the presence of an input supply. The logic supply voltage must be less than 5.5V.
Charge-Timer Selection
Set the maximum charging time with the TMAX threelevel logic input. TMAX limits the duration of charging to protect the battery from overcharging. Connect TMAX to GND to set the maximum charging time to 3 hours. Leave TMAX floating to set the maximum charging time
AC ADAPTER
4.5V TO 6.5V IN 1F INP
BATT
4.2V 1-CELL Li+ 10F AC ADAPTER 4.5V TO 6.5V IN 1F INP
BATT
4.2V 1-CELL Li+ 10F
MAX1501 MAX1501
GLED RLED TMAX ACOK TEMP FULLI SETI 2.8k GND GND 2.8k
VL SELV MODE CHGEN
GLED RLED VI/O P
RPULLUP
TMAX TEMP FULLI
ACOK CHGEN SETI MODE GND GND
VL SELV
Figure 4. Stand-Alone Li+ Battery Charger 12
Figure 5. P-Based Li+ Battery Charger
______________________________________________________________________________________
Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
AC ADAPTER 4.75V TO 6.5V IN 1F INP
BATT
4.5V 3-CELL NiMH OR NiCd 10F AC ADAPTER 1F
5.25V TO 6.5V IN INP
BATT
4.95V 3-CELL NiMH OR NiCd 10F
MAX1501
GLED RLED TMAX SETI 2.8k
TEMP ACOK FULLI SELV VL MODE
MAX1501
GLED RLED VI/O P
RPULLUP TMAX TEMP FULLI
ACOK CHGEN SETI 2.8k
VL SELV MODE
CHGEN GND GND
GND GND
Figure 6. Stand-Alone 3-Cell NiMH or NiCd Battery Charger
Figure 7. P-Based NiMH or NiCd Battery Charge
Figure 6 shows the MAX1501 as a stand-alone NiMH/NiCd battery charger. Connecting SELV to GND sets the charge termination voltage to 4.5V. Figure 7 shows the MAX1501 as a P-based NiMH/NiCd battery charger. Connecting SELV to VL sets the charge regulation voltage at 4.95V. Connect a 100k pullup resistor from ACOK to the logic supply voltage of the P. The logic supply voltage must be less than 5.5V.
4.1V 1-CELL Li+ OR 4.5V 3-CELL NiMH/NiCd IN 1F INP
BATT
AC ADAPTER
4.75V TO 6.5V
Figure 8 shows the MAX1501 as a P-based single Li+ or 3-cell NiMH/NiCd charger. The states of MODE and CHGEN set the operating mode of the MAX1501 (Table 1). Connect a 100k pullup resistor from ACOK to the logic supply voltage of the P. The logic supply voltage must be less than 5.5V. Figure 9 shows the MAX1501 as an accurate currentlimited low-dropout linear regulator with input overvoltage protection (no-battery mode). The output voltage regulates to 4V, regardless of the state of SELV. Connect MODE to VL to enable the linear regulator. Connect MODE to GND to put the device into shutdown. RSETI sets the maximum output current.
4.5V TO 6.5V 4V IN 1F INP
BATT
10F
MAX1501
GLED RLED VI/O
100k VL
GLED
10F
MAX1501
RLED
VL
ACOK P CHGEN MODE SETI 2.8k
FULLI TMAX SELV TEMP
FULLI TEMP TMAX
CHGEN
ON
MODE
OFF
ACOK
GND GND
SETI CURRENT-LIMIT ADJUST UP TO 1.4A GND
SELV
GND
Figure 8. P-Based Single Li+/3-Cell NiMH/NiCd Battery Charger
Figure 9. Input Overvoltage-Protected and Current-Limited Low-Dropout Linear Regulator 13
______________________________________________________________________________________
Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications MAX1501
5V
5.1k
4.1k
3k 100k
200k
3k
IN
MAX1501
CHGEN 2.24k 5V 1k GND 3k 100k TBATT RT = 10k AT +25C 10k 3.66k 0C 1k +25C +50C RT 27.28k 10.00k 4.16k
Figure 10. Battery Temperature Protection
Figure 10 shows a circuit that adds temperature protection to the battery. Install the thermistor as close to the battery as possible to ensure accurate temperature measurement. The output of this circuit is logic high when the battery temperature is less than 0C and greater than +50C. Driving CHGEN high disables the charger.
Chip Information
TRANSISTOR COUNT: 5717 PROCESS: BiCMOS
Layout and Bypassing
Connect IN and INP together as close to the device as possible and bypass with a 1F ceramic capacitor. Bypass BATT to GND with a 10F ceramic capacitor. Provide a large copper GND plane to allow the exposed paddle to sink heat away from the device. Connect the battery to BATT as close to the device as possible to provide the most accurate battery voltage sensing. Make all high-current traces short and wide to minimize voltage drops.
GLED RLED
Pin Configuration
SELV 14 GND 13 12 BATT 11 ACOK 10 CHGEN 9 8 TEMP MODE
16 INP IN GND SETI 1 2 3 4 5 VL
15
MAX1501
**EXPOSED PADDLE 6 TMAX 7 FULLI
5mm x 5mm THIN QFN **CONNECT EXPOSED PADDLE TO GND
14
______________________________________________________________________________________
Highly Integrated, Linear Battery Charger with Thermal Regulation for Portable Applications
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
QFN THIN.EPS
MAX1501
0.15 C A
D2
C L
D
b D2/2
0.10 M C A B
PIN # 1 I.D.
D/2
0.15 C B
k
PIN # 1 I.D. 0.35x45
E/2 E2/2 E (NE-1) X e
C L
E2
k L
DETAIL A
e (ND-1) X e
C L
C L
L
L
e 0.10 C A 0.08 C
e
C
A1 A3
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE 16, 20, 28, 32L, QFN THIN, 5x5x0.8 mm
APPROVAL DOCUMENT CONTROL NO. REV.
21-0140
C
1 2
COMMON DIMENSIONS
EXPOSED PAD VARIATIONS
NOTES: 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220. 10. WARPAGE SHALL NOT EXCEED 0.10 mm.
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE 16, 20, 28, 32L, QFN THIN, 5x5x0.8 mm
APPROVAL DOCUMENT CONTROL NO. REV.
21-0140
C
2 2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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