LM2902: LM2902 question.

Ahn Young Taek

Prodigy 40 points

Part Number: LM2902
Other Parts Discussed in Thread: TPS562203, TPSM861252

Tool/software:

I want to use OPAMP LM2902 with +12V input and +3.3V output for each channel. 0.5A per channel

How should I configure the circuit?

If there is a way to meet the above specifications even if it is not an LM2902, please recommend it.

5 months ago

0 Clemens Ladisch 5 months ago

Guru 279540 points

Do you want to build a power supply? In that case, use an integrated power module like the TPSM861252, or build your own with a buck converter like the TPS562203. (For two channels, use two of them.)

0 Ahn Young Taek 5 months ago in reply to Clemens Ladisch

Prodigy 40 points

I'm trying to change the input 12V to the output 3.3V 2.8V to power the LED.
Couldn't it be configured with OPAMP instead of Buck?
I need 4 channels.

0 Clemens Ladisch 5 months ago in reply to Ahn Young Taek

Guru 279540 points

The opamp would have to dissipate 4 × (12 V − 2.8 V) × 0.5 A = 18.4 W. That would require extremely good cooling.

Just to be clear: you have four LEDs, with a forward voltage of about 2.8 V, and want to run them with 500 mA each? Do you need to switch them on/off separately? Do you want to dim them?

0 Ron Michallick 5 months ago in reply to Ahn Young Taek

TI__Guru*** 149626 points

Hello Ahn Young Taek,

Here are some 12V quad channel LED drivers that can do 500mA

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LM2902: LM2902 question.