A8431EEHTR-T

A8431EEHTR-T Datasheet

A8431 White LED Driver Constant Current Step-up Converter

Part	Datasheet
A8431EEHTR-T	A8431EEHTR-T (pdf)

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A8431 White LED Driver Constant Current Step-up Converter Last Time Buy These parts are in production but have been determined to be LAST TIME BUY. This classification indicates that the product is obsolete and notice has been given. Sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because of obsolescence in the near future. Samples are no longer available. Date of status change November 2, 2009 Deadline for receipt of LAST TIME BUY orders April 30, 2010 Recommended Substitutions: NOTE For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. A8431 White LED Driver Constant Current Step-up Converter Output voltage up to 32 V OVP level to 10 V input Drives up to 4 LEDs at 20 mA from a V supply Drives up to 5 LEDs at 20 mA from a 3 V supply MHz switching frequency 300 mA switch current limit 1 uA shutdown current OVP pin eliminates the need for an external Zener diode on the output Package 6-pin MLP/DFN suffix EH Approximate scale The A8431 is a noninverting boost DC-DC converter that provides a programmable constant-current output up to 32 V for driving white LEDs in series.The A8431 also offers an OVP overvoltage protection pin. Driving the 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 two parallel strings of eight white LEDs can be driven at 20 mA by increasing the supply voltage up to 10 V. The A8431 incorporates a power switch and a 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 a filtered PWM signal when dimming control is required. The high switching frequency of MHz allows the use of small inductor and capacitor values. The A8431 is provided in a mm nominal height, 6-pin, 2 mm x 3 mm MLP package. It is lead Pb free, with 100% matte tin leadframe plating. Applications include: LED backlights Portable battery-powered equipment Cellular phones PDAs Personal Digital Assistant Camcorders, personal stereos, MP3 players, cameras Mobile GPS systems Functional Block Diagram VREF A1 95 mV EN Enable A2 RC Ramp Generator MHz Oscillator Driver A8431 White LED Driver Constant Current Step-up Converter Selection Guide Packing* A8431EEHTR-T 1500 pieces per 7-in. reel *Contact Allegro for additional packing options Absolute Maximum Ratings Characteristic SW Pin Voltage OVP Pin Voltage Remaining Pin Voltage Operating Ambient Temperature Maximum Junction Temperature Storage Temperature Symbol VSW VOVP TA TJ max Tstg Range E Notes Rating to 36 to 36 to 10 to 85 150 to 150 Units V ºC ºC ºC Pin-out Diagram

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A8431 White LED Driver Constant Current Step-up Converter

Last Time Buy

These parts are in production but have been determined to be LAST TIME BUY. This classification indicates that the product is obsolete and notice has been given. Sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because of obsolescence in the near future. Samples are no longer available. Date of status change November 2, 2009 Deadline for receipt of LAST TIME BUY orders April 30, 2010

Recommended Substitutions:

NOTE For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative.

A8431 White LED Driver Constant Current Step-up Converter

Output voltage up to 32 V OVP level to 10 V input Drives up to 4 LEDs at 20 mA from a V supply Drives up to 5 LEDs at 20 mA from a 3 V supply MHz switching frequency 300 mA switch current limit 1 uA shutdown current OVP pin eliminates the need for an external Zener diode
on the output

Package 6-pin MLP/DFN suffix EH

Approximate scale

The A8431 is a noninverting boost DC-DC converter that provides a programmable constant-current output up to 32 V for driving white LEDs in series.The A8431 also offers an OVP overvoltage protection pin. Driving the 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 two parallel strings of eight white LEDs can be driven at 20 mA by increasing the supply voltage up to 10 V.

The A8431 incorporates a power switch and a 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 a filtered PWM signal when dimming control is required. The high switching frequency of MHz allows the use of small inductor and capacitor values.

The A8431 is provided in a mm nominal height, 6-pin, 2 mm x 3 mm MLP package. It is lead Pb free, with 100% matte tin leadframe plating.

Applications include:

LED backlights Portable battery-powered equipment Cellular phones PDAs Personal Digital Assistant Camcorders, personal stereos, MP3 players, cameras Mobile GPS systems

Functional Block Diagram

VREF

A1 95 mV

EN Enable

A2 RC

Ramp Generator

MHz Oscillator

Driver

A8431

White LED Driver Constant Current Step-up Converter

Selection Guide

Packing*

A8431EEHTR-T
1500 pieces per 7-in. reel
*Contact Allegro for additional packing options

Absolute Maximum Ratings

Characteristic SW Pin Voltage OVP Pin Voltage Remaining Pin Voltage Operating Ambient Temperature Maximum Junction Temperature Storage Temperature

Symbol VSW VOVP

TA TJ max

Tstg

Range E

Notes

Rating to 36 to 36 to 10 to 85
150 to 150

Units V ºC ºC ºC

Pin-out Diagram

Notice: we do not provide any warranties that information, datasheets, application notes, circuit diagrams, or software stored on this website are up-to-date or error free. The archived A8431EEHTR-T Datasheet file may be downloaded here without warranties.

Datasheet ID: A8431EEHTR-T 516074