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A8430
White LED Driver Constant Current Step-up Converter
The A8430 is a noninverting boost converter that steps-up the input voltage, to provide a programmable constant current output at up to 36 V for driving white LEDs in series. Driving LEDs in series ensures identical currents and uniform brightness. Up to four white LEDs can be driven at 20 mA from a single cell Li-ion or a multicell NiMH power source. Up to seven white LEDs can be driven by increasing the supply voltage up to 10 V. The A8430 incorporates a power switch and feedback sense amplifier to provide a solution with minimum external components. The output current can be set by adjusting a single external sense resistor and can be varied with a voltage or filtered PWM signal when dimming control is required. The high switching frequency of 1.2 MHz allows the use of small inductor and capacitor values. The A8430 is provided in a 5-pin 3 mm x 3 mm MLP package (part number suffix EK), that has a nominal height of only 0.75 mm. The lead-free version (part number suffix EK-T) has 100% lead-free matte tin leadframe plating.
Data Sheet
26185.300C
A8430 MLPD
Approximate actual size
SW GND FB
1 2 3
5
VIN
4
EN
Same pad footprint as SOT-23-5 RθJA = 50 °C/W, see note 1, page 2
FEATURES
Output voltage up to 36 V 2.5 V to 10 V input Drives up to 4 LEDs at 20 mA from a 2.5 V supply Drives up to 5 LEDs at 20 mA from a 3 V supply 1.2 MHz switching frequency 300 mA switch current limit 1 µA shutdown current
ABSOLUTE MAXIMUM RATINGS
SW Pin ................................................–0.3 V to 36 V Remaining Pins .................................. –0.3 V to 10 V Ambient Operating Temperature, TA....... –40°C to 85°C Junction Temperature, TJ(max)............................... 150°C Storage Temperature, TS .................... –55°C to 150°C
APPLICATIONS
LED backlights Portable battery-powered equipment Cellular phones PDAs (Personal Digital Assistant) Camcorders, personal stereos, MP3 players, cameras Mobile GPS systems
Use the following complete part number when ordering:
Part Number A8430EEK A8430EEK-T Package 5-pin, MLPD 5-pin, MLPD Description Surface Mount Lead-Free, Surface Mount
Data Sheet
26185.300C
White LED Driver Constant Current Step-up Converter
Functional Block Diagram
FB SW
A8430
VIN
VREF 1.25 V
95 mV
A1 RC CC A2 R S Q Driver
Σ
Ramp Generator EN
Enable
1.2 MHz Oscillator
GND
ELECTRICAL CHARACTERISTICS at TA = 25°C, VIN = 3 V (unless otherwise noted)
Characteristics Input Voltage Range Supply Current Feedback Reference Voltage Feedback Input Current Switch Current Limit Switch Frequency Switch Maximum Duty Cycle Switch Saturation voltage Switch Leakage Current Enable Input Input Threshold Low Input Threshold High Input Leakage VIL VIH Leakage – – IIL – 1.5 – – – – 0.4 – 1 V V µA Symbol VIN ISUP VREF IFB ISWLIM FSW D VCE(SAT) ISL – Active: ILOAD = 15 mA, VLOAD = 12 V Shutdown (EN = 0 V) – – – – – – – Test Conditions Min. 2.5 – – 86 – – 0.