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SP7685
1.2A Buck/Boost Charge Pump LED Driver
FEATURES ■ Output Current up to 1.2A ■ Up to 94% Efficiency in Torch Mode ■ Adjustable FLASH Mode Current ■ Minimum External Components: No Inductors ■ Automatic Buck/Boost Mode Switchover ■ Wide VIN Range: 2.7V to 5.5V ■ High Frequency Operation: 2.4 MHz ■ 50mV Reference for low Loss Sensing ■ IQ < 2μA in Shutdown ■ PWM Dimming Control ■ Automatic Soft Start Limits Inrush Current ■ Overvoltage Protection on Output ■ Overcurrent/temperature Protection ■ Low Ripple and EMI ■ Ultra-low Dropout Voltage in Buck Mode ■ 2.6 Second Timeout in Flash Mode ■ Space Saving RoHS Compliant, Lead Free Package: 10-pin 3mm x 3mm DFN
VIN C1 C2 FLASH EN
1 2 3 4 5 10
VOUT PGND SGND FB RSET
SP7685
10 Pin DFN
9 8 7 6
APPLICATIONS ■ White LED Torch/Flash for Cell Phones, DSCs, and Camcorders ■ White LED Backlighting ■ Generic Lighting/Flash/Strobe Applications ■ General Purpose High Current Boost
DESCRIPTION The SP7685 is a current-regulated charge pump ideal for powering high brightness LEDs for camera flash applications. The charge pump can be set to regulate two current levels for FLASH and TORCH modes. The SP7685 automatically switches modes between step-up and step-down ensuring that LED current does not depend on the forward voltage. A low current sense reference voltage (50mV) allows the use of small 0603 current sensing resistors. The SP7685 is offered in 10-pin DFN package. TYPICAL APPLICATION CIRCUIT
VIN (3.0 - 4.2V)
O
CIN 10μF VIN CFC 1μF
¤
VOUT COUT 10μF 1A Flash 200mA Torch PWF1 WLED
C1 SP7685 PGND C2 SGND FLASH EN FB RSET RSET 80KΩ
TORCH/FLASH ENABLE
RSENSE 0.22Ω
Date: 6/20/06 Rev T
SP7685, 1.2A Buck/BoostCharge Pump LED Driver
© 2006 Sipex Corporation
1
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VIN , VOUT ....................................................................... -0.3V to 6V Output Current Pulse (Flash) ................................. 2A Output Current Continuous (Torch) ..................... 0.4A Storage Temperature ...................... -65°C to +150°C Operating Temperature ..................... -40°C to +85°C VEN ............................................................ 0.0V to 7V 3x3 10 DFN .........................................OJA = 40.5°C/W ESD Rating. ................................................ 2kV HBM
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
ELECTRICAL CHARACTERISTICS
TA = -40°C to +85°C, VIN =3.6V, CIN = 10μF, CFC =1.0μF, COUT =10μF. VSHDN = VIN, typical values at 25°C. The ♦ denotes the specifications which apply over the full operating temperature range unless otherwise noted.
PARAMETER Operating Input Voltage Quiescent Current
MIN. 2.7
TYP.
MAX. 5.5
UNITS V mA ♦ ♦
CONDITIONS
0.5 2
3
V IN = 2.7 - 5.5V FLASH = GND, 1X Mode, ILOAD = 100μA FLASH = High, 2x mode
Shutdown Current Oscillator Frequency Charge Pump Equivalent Resistance (x2 mode) Charge Pump Equivalent Resistance (x1 mode) 45 FB Reference Voltage 138 FB Reference Voltage Range FB Pin Current EN, FLASH Logic Low EN, FLASH Logic High EN, FLASH Pin Current V OUT Turn-on Time Thermal Shutdown Temperature Maximum Flash ON time 1.6 170 145 2.6 1.3 100 150 2.4 4 0.4 50
2
μA MHz Ω
V IN = 5.5V, VEN = 0.0V
V FB = 0.0V, V IN= 3.6V V IN = 3.6V ♦ ♦ ♦ FLASH = GND FLASH = High, R SET = 53.6kΩ . FLASH = High. Guaranteed by design. V FB = 0.3V ♦ ♦ ♦ ♦ V IN = 3.6V, FB within 90% of regulation
0.7 55 162 400 0.5 0.4
Ω mV mV mV μA V V
0.5 500
μA μs
o
C ♦ FLASH = High
3.6
s
Date: 6/20/06 Rev T
SP7685, 1.2A Buck/BoostCharge Pump LED Driver
© 2006 Sipex Corporation
2
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PIN DESCRIPTION
PIN PIN NAME NUMBER 1 2 VIN C1
DESCRIPTION Input Voltage for the charge pump. Decouple with 4.7µF ceramic capacitor close to the pins of the IC. Positive input for the external flying capacitor. Connect a ceramic 1µF capacitor close to the pins of the IC. Negative input for the external flying capacitor. Connect a ceramic 1µF capacitor close to the pins of the IC. Logic input to toggle operation between FLASH and TORCH mode. In TORCH mode FB is regulated to the internal 50mV reference. In FLASH mode FB reference voltage can be adjusted by changing the resistor from RSET pin to ground. Choose the external current sense resistor (R SENSE) based on desired current in TORCH mode. This pin does not have an internal pull-up/pulldown; do not leave this pin floating. Shutdown control input. Connect to VIN for normal operation, connect to ground for shutdown. This pin does not have an internal pull-up/pull-down; do not leave this pin floating. Connect a resistor from this pin to ground. When in FLASH mode (FLASH = High) this resistor sets the current regulation point according to the followin.