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High Output Current Charge Pump Doubler
POWER MANAGEMENT Description
The SC1462 is a versatile charge pump designed for use in battery operated power supply applications over the wide input range of 1.65 to 5.5 volts. A simple, low quiescent current charge pump doubler can be implemented without costly inductors or capacitors. Internal MOSFETs and control circuitry eliminate the need for costly board space and design time. The small 6 lead SOT-23 package helps minimize board space. The SC1462 charge pump can be used for applications that require up to 80mA of output current with VIN = 2.5V to 5.5V. Typical dropout voltage (2xVIN)-VOUT is shown below for several values of VIN.
Typical Dropout Voltage vs. IOUT @TA = 25 Deg. C.
0.9 0.8
VIN = 1.5V VIN = 2.5V VIN = 3.6V VIN = 4.5V VIN = 5.5V
SC1462
Features
Input supply voltage range of 1.65V to 5.5V Small size - 6 pin SOT-23 package Typical efficiency of : 91% @ VIN = 2.5V, IOUT = 45mA 94% @ VIN = 3.6V, IOUT = 55mA Short circuit and over-temperature protection 140A typical input current @ no load Shutdown current <1A Designed to work with ceramic or tantalum capacitors Fixed frequency of 160kHz All specifications rated over full temperature range (-40C to 85C)
Output Dropout Voltage (V)
0.7 0.6 0.5 0.4 0.3 0.2
Applications
Cellular phones Handheld devices LCD Display
Typical Application Circuit 0.1
0.0 000E+0 20E-3 40E-3 60E-3 80E-3 100E-3
IOUT (A)
Typical Application Circuit
Logic Control or GND
4 1 CIN 3.3F
SC1462
SHDN VIN C+ VOUT
5 COUT
VOUT 3.3F
VIN
6 CBUCKET 3.3F
CGND 2
3
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SC1462
POWER MANAGEMENT Absolute Maximum Ratings (1)
Exceeding the specifications below may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied.
Parameter Supply Voltage Output Voltage VOUT Short Circuit Duration Thermal Resistance Junction to Ambient(2) Operating Ambient Temperature Range Junction Temperature Range Storage Temperature Range Peak IR Flow Temperature, SC1462ISKTR Peak IR Flow Temperature, SC1462ISKTRT
Symbol VIN VOUT SC
Maximum -0.3 to +6.0 -0.3 to +12 Indefinite 230 -40 to +85 -40 to +125 -65 to +150 240 260
Units V V
JA
TA TJ TSTG TLEAD TLEAD
C/W C C C C C
Notes: 1) This device is ESD sensitive. Use of standard ESD handlng precautions is required. 2) Calculated from package in still air, mounted to 3" x 4.5", 4 layer FR4 PCB with thermal vias under the exposed pad as per JESD51 standards.
Electrical Characteristics
Unless specified: TA = -40C to 85C, SHDN = GND, 1.65V VIN 5.5V, Frequency =160kHz, CIN = COUT = CBUCKET = 3.3F (ESR = 0.3).
Parameter Input Supply Voltage
Symbol VIN
Conditions
Min 1.65
Typ
Max 5.5
Units V A A A mA mA kHz
IOUT = 0, VIN = 2.5V Input Supply Current IIN IOUT = 0, VIN = 3.6V SHDN = VIN Ouput Resistance(1) Output Resistance(1) Total Switch Resistance(2) Total Switch Resistance(2) Output Current ROUT ROUT RSW RSW IOUT fOSC VIN = 2.5V VIN = 3.6V VIN = 2.5V VIN = 3.6V VIN = 2.5V VIN = 3.6V 100
140 200 0.1 9.5 7.5 3 2
260 400 1 13.5 10.5 4.5 3 80 80
Oscillator Frequency
160
200
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SC1462
POWER MANAGEMENT Electrical Characteristics (Cont.)
Parameter Short Circuit Current Output Ripple (pk-pk)(3)(4) Power Efficiency(3) Maximum Output Voltage(4) Time to Regulation at Turn-On(5) Input High Threshold Input Low Threshold Over-Temperature Protection(4) Over-Temperature Hystereis(4) Symbol ISC VR VOUT tON VIN VIL TOT Hysteresis Conditions VOUT = 0V IOUT = 45mA, VIN = 2.5V IOUT = 45mA, VIN = 2.5V IOUT = 0mA IOUT = 0 to 60mA, VIN = 3.6V SHDN pin, 2.5V VIN 5.5V SHDN pin, 2.5V VIN 5.5V 140 20 1.6 0.4 500 86 2xVIN Min Typ 200 75 Max Units mA mV % V s V V C C
Notes: 1) The internal switch resistance, the capacitor ESR and the oscillator's switching frequency all contribute to ROUT. See the CAPACITOR SELECTION section on Page 6 for information on applying the ROUT specification. 2) The parameter RSW is equal to the total resistance of all 4 internal switches. See the CAPACITOR SELECTION section for information on applying the RSW specification. The parameter was calculated from actual output resistance and the equation on Page 6 for ROUT. 3) All electrical characteristics are for the Typical Application Circuit on Page 1. 4) Guaranteed by design. 5) Soft start functionality is performed along with short circuit protection. If VOUT is less than VIN - 200mV, then all switches are turned off and VOUT is charged with a 200mA current source from VIN. When VOUT reaches VIN - 200mV all switches are enabled.
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SC1462
POWER MANAGEMENT
Pin Configuration
Ordering Information
DEVICE(1) SC1462ISKTR SC1462ISKTRT(2) PACKAGE( SOT-23-6 SOT-23-6
1)
Notes: 1) Available in tape and reel only. A reel contains 3,000 devices. 2) This Pb free device is WEEE and RoHS compliant.
Pin Descriptions
Pin# 1 2 3 4 5 6 Pin Name VIN GND CSHDN VO C+ Pin Function Supply input voltage. Ground. This pin should be connected to the negative terminal of the external charging capacitor. Shutdown pin. When this pin is connected to VIN, the device enters sleep mode. Voltage output. This pin should be connected to the positive terminal of the external charging capacitor.
Block Diagram
Marking Information
Top Mark 1462
yyww
Bottom Mark
yyww = Datecode (Example : 0552)
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SC1462
POWER MANAGEMENT Pin Configuration Applications Information
Theory of Operation The SC1462 utilizes a switched capacitor charge pump to generate an output voltage approximately 2xVIN. An internal oscillator generates two out of phase fixed frequency clock signals which turn on and off internal MOSFET switches. During phase 1, the flying charge pump capacitor is charged to VIN through switches S1 and S2. During phase 2, the flying charge pump capacitor is connected in series with the input voltage via S3 and S4, producing an output voltage. If VOUT is less than VIN - 200mV, then all switches are turned off and VOUT is charged with a 200mA current source from VIN. When VOUT reaches VIN - 200mV, the current source is disconnected from output and the charge pump circuitry is enabled again. Output Current The dropout voltage for a charge pump doubler is defined as (2xVIN) - VOUT. The maximum output current is usually specified as that which will not cause the dropout voltage to exceed the requirements of the application. The calculation of the dropout voltage is given in the capacitor selection section on Page 6. Typical dropout voltages versus IOUT are graphed on Page 8. Thermal Shutdown The thermal shutdown circuit provides added protection to the SC1462. During a VOUT short circuit condition or if the load is excessive, the over-temperature circuitry will shut down the charge pump if the junction temperature exceeds approximately 140C. The charge pump is enabled only if the junction temperature drops to approximately 120C. The SC1462 will cycle in and out of thermal shut down until the short circuit or the excessive load condition on VOUT is removed, thereby improving device reliability. The junction temperature can be calculated from the following formula if the ambient temperature (TA) and the charge pump power dissipation (PDISS) are known. TJ = TA + PDISS x JA ; JA = 230 C/W
Doubler
Charge transfer from CIN to CBUCKET ON S1,S2 OFF ON S3,S4 OFF Charge transfer from: CIN and CBUCKET to COUT (Doubler)
S1 1 2 1
S4 2
VOUT = 2 x VIN
COUT
CBUCKET
VIN
Cin
S3 1 2 1
S2 2
Short Circuit/Soft-Start An internal current limit and soft-start circuit provides protection against output short circuit and limits large current spikes generated during the initial start-up to charge output capacitor.
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SC1462
POWER MANAGEMENT
Applications Information (Cont.)
Capacitor Selection Capacitor selection is based on both the maximum acceptable ripple voltage and the maximum tolerable drop at the output. This equation can be used to calculate CBUCKET for a specific VOUT when VIN and IOUT are known. The maximum value for the RSW from the Electrical Characteristics section on Page 2 should be used in order to find a worst-case number. Layout Consideration Standard power board layout should be followed to ensure proper operation. Any stray inductance should be minimized, this can be achieved by using large power planes or traces, and reducing the distances between input, output and the load. All components should be placed as close as possible to the SC1462. The following table shows typical capacitor characteristics.
Component 0.1F Ceramic 0603 Package 1.0F Ceramic 1206 Package 10F Ceramic 0603 Package 47F Ceramic, 16V Tantalum D case 330F, 6.3V "OSCON" 330F, 16V AL. Electrolytic 820F, 4V "OSCON" 1000F, 10V Al. Electrolytic ESR() 0.050 0.040 0.075 0.100 0.025 0.143 0.012 0.053 ESL(nH) 1.60 0.47 0.50 0.60 2.50 2.37 2.50 5.00
Ripple
The peak-to-peak output ripple voltage is dependent on the following factors: 1) Oscillator frequency 2) ESR of COUT 3) Capacitance value of COUT Item 1 is fixed and depend on the charge pump device used. Item 2, and 3 can be optimized for best performance and reduction of the output ripple. The following formula could be used for an approximation for VOUT_RIPPLE.
VOUT_RIPPLE =
IOUT
2 x fOSC x COUT
+ 2 x I x ESR_ COUT
VOUT Drop
The voltage drop at the output is specified with the following equation: VOUT_DROP = IOUT x ROUT ROUT is dependent on the following factors: 1) 2) 3) 4) Oscillator frequency ESR of COUT & CBUCKET Capacitance value of COUT and CBUCKET Internal switch resistance (RSW = Total of all 4 switch resistances).
A good approximation for calculating the output resistance is shown below.
ROUT =
1
fOSC x CBUCKET
+ 2 x RSW + 4 x ESR_ CBUCKET + ESR_ COUT
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SC1462
POWER MANAGEMENT Applications Information (Cont.)
VIN = 3V to 5.5V U1 SC1462 1 VIN Vo 5 6 3 1 2 CBUCKET 3.3F COUT 3.3F 3 VIN GND EN BYPASS 4 C2 10nF 2 C3 1F U2 SC2982 VOUT 5 VOUT = 5V
CIN 3.3F
4 SHDN C+ GND C-
EN
5 Volts Fixed Ouput Voltage
VIN = 2V to 3V U1 SC1462 1 VIN Vo 5 6 3 1 IN 3 EN U2 SC1453 OUT GND BYP 2 5 4 C2 10nF C3 1F VOUT = 3.3V
CIN 3.3F
4 SHDN C+ GND 2 C-
CBUCKET 3.3F
COUT 3.3F
EN
3.3 Volts Fixed Ouput Voltage
VIN = 3.3V
10
BSTH
DRV H
6
4 SC1462 1 4 VIN Vo 5 6 3 14 2 13 9
OCSET
PHASE
5
BSTL
DRV L
8
SHDN C+ GND C-
1
VCC
PGND
7
GND
VREF
12
SS/SHDN
Sense
11
Power Good
2
PWRGD
OVP
3
SC1102
(3.3V Input Supply) Battery Operated Synchronous Buck Converter
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SC1462
POWER MANAGEMENT
Typical Characteristics
Typical IIN vs. VIN, IOUT = 0mA
Typical IIN vs. VIN @TA = 25 Deg. C.
0.9 700E-6 600E-6 500E-6 0.8
VIN = 1.5V VIN = 2.5V VIN = 3.6V VIN = 4.5V VIN = 5.5V
Typical Dropout vs. IOUT
Typical Dropout Voltage vs. IOUT @TA = 25 Deg. C.
Output Dropout Voltage (V)
IOUT = 0mA
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0
IIN (A)
400E-6 300E-6 200E-6 100E-6 000E+0 1.0 2.0 3.0 4.0 5.0 6.0
000E+0
20E-3
40E-3
60E-3
80E-3
100E-3
VIN (V)
IOUT (A)
Typical IIN vs. TA, IOUT = 0mA
Typical IIN vs. TA @ IOUT = 0mA
900E-6
VIN = 5.5V
Typical Dropout vs. TA
Typical Dropout Voltage vs. TA
550E-3
800E-6 700E-6 600E-6
VIN = 4.5V
VIN = 2.5V, IOUT = 50mA
Output Dropout Voltage (V)
VIN = 3.6V VIN = 2.5V VIN = 1.5V
500E-3
VIN = 3.6V, IOUT = 60mA
450E-3
IIN (A)
500E-6 400E-6 300E-6 200E-6 100E-6 000E+0 -40 -20 0 20 TA (Deg. C.) 40 60 80
400E-3
350E-3
300E-3 -40 -20 0 20 40 60 80
TA (Deg. C.)
Typical Efficiency vs. IOUT
Typical Efficiency vs. IOUT @TA = 25 Deg. C.
100%
Typical Output Ripple
96%
VOUT Ripple 50mV/Div.
Efficiency (%)
92%
88%
VIN = 5.5V
84%
VIN = 4.5V VIN = 3.6V VIN = 2.5V VIN = 1.5V
VIN = 3.6V IOUT = 60mA CIN = COUT = CBUCKET = 3.3F
80E-3 100E-3
80% 000E+0 20E-3 40E-3 60E-3
IOUT (A)
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SC1462
POWER MANAGEMENT Outline Drawing - SOT-23-6L
DIMENSIONS INCHES MILLIMETERS MIN NOM MAX MIN NOM MAX
.057 .035 .000 .006 .035 .045 .051 .010 .020 .003 .009 .110 .114 .122 .060 .063 .069 .110 BSC .037 BSC .075 BSC .012 .018 .024 (.024) 6 0 10 .004 .008 .008 1.45 0.90 0.00 0.15 .90 1.15 1.30 0.25 0.50 0.08 0.22 2.80 2.90 3.10 1.50 1.60 1.75 2.80 BSC 0.95 BSC 1.90 BSC 0.30 0.45 0.60 (0.60) 6 0 10 0.10 0.20 0.20
A e1 N EI 1 ccc C 2X N/2 TIPS B 2 E D
DIM
A A1 A2 b c D E1 E e e1 L L1 N 01 aaa bbb ccc
2X E/2
e
D aaa C A2 SEATING PLANE C A1 bxN bbb C A-B D A
H GAGE PLANE 0.25 L (L1) SEE DETAIL c
01
A
DETAIL
A
SIDE VIEW
NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
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SC1462
POWER MANAGEMENT
Land Pattern - SOT-23-6L
X
DIM
(C) G Y P Z C G P X Y Z
DIMENSIONS MILLIMETERS INCHES
(.098) .055 .037 .024 .043 .141 (2.50) 1.40 0.95 0.60 1.10 3.60
NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET.
Contact Information
Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 FAX (805) 498-3804
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