Using 2 LM3492 Circuits for 4 LED Strings in Backlight

George Ioakimedes

Other Parts Discussed in Thread: LM3492, TPS61199

I have a input power source of 12-22VDC and need to power the backlight of a LM215WF3 LCD Panel. I have created a circuit for 2/4 strings and then duplicated the circuit for the other 2 strings but I'm concerned about combining the 2 outputs.

I couldn't really find a better solution so perhaps the LM3492 is not the right part. Since each string requires 110mA and there's 4 strings that elimated most parts.

Thanks,

George

over 10 years ago

0 Victor Chen_HK over 10 years ago

TI__Expert 5130 points

Hello George,

It is OK to combine two LED strings together as long as the total current does not exceed 400mA (200mA per output).

Regards,

Victor

0 George Ioakimedes over 10 years ago in reply to Victor Chen_HK

Genius 4950 points

Hi Victor:

Sorry, my question is not about combining the 2 LED strings on the same LM3492, my question is that my panel has 4 strings of LEDs so I need 2 LM3492 and I'm questioning about bridging the 2 circuits together. I don't think this is a good idea since you don't know what the voltage will be on each string but maybe there is a way as I've seen other LED controllers with the ability to cascade them. Or, perhaps there's a different part that can provide 4 strings of LEDs with 110mA per string.

George

0 Victor Chen_HK over 10 years ago in reply to George Ioakimedes

TI__Expert 5130 points

Hello George,

Then you may try TPS61199. It can support 8 channels with maximum current 70mA per channel. But you can connect two channels together to double the current.

Best regards,

Victor

0 George Ioakimedes over 10 years ago in reply to Victor Chen_HK

Genius 4950 points

Yep, I missed that one!

Power management

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Using 2 LM3492 Circuits for 4 LED Strings in Backlight