3V led driver with 3.3V power supply

ernst van spronsen

Other Parts Discussed in Thread: LP5562

Hello,

I like to know the TI suggested sollution to control a 3V LCD backlight led at 85mA at 3.3V. The voltagedrop for a resistor is a bit low. I didn't find any low voltage drop current source and a boost converter is a bit much.

So I'm not the first persoon with this problem. What is the sugested sollution for this?

Thanks,

EVS

over 2 years ago

0 Patrick Yao over 2 years ago

TI__Mastermind 34840 points

Hi,

Since Vin and Vout are too close, I'd suggest buck-boost LED drivers or linear LED drivers. You can also use separate components to build up a control circuit.

Do you have more specific spec requirements so I can better recommend you with our ICs? Info like below:

(1) How many LED strings in your application?

(2) Need interface or not (like I2C, SPI...)?

Patrick

0 ernst van spronsen over 2 years ago in reply to Patrick Yao

Prodigy 50 points

OK.

Why do I need the buck part for? A lineair driver is only an option if the voltage drop is really low.

There are 4 single leds in parallel. Total current is 85mA. All I need is brightness controll.

Thanks,

Ernst

0 Patrick Yao over 2 years ago in reply to ernst van spronsen

TI__Mastermind 34840 points

Hi Ernst,

I'd recommend out LP5562, it's 4 channels LED drivers with Max 22.5mA per channel.

The LEDs are powered with external supply and the extra voltage will directly drop on IC pins.

LP5562

Patrick

Power management

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3V led driver with 3.3V power supply