TL431: frequency issue

Cherry Zhou

Part Number: TL431

Hi team,

Here's an issue from the customer may need your help:

The customer is wondering if LLC can use optocoupler +TL431 for closed loop at high frequencies such as 300 kHz or 1 MHz. And will optocouplers not respond as quickly as possible?

Could you help check this case? Thanks.

Best Regards,

Cherry

over 2 years ago

+1 Walter Zollinger over 2 years ago

TI__Expert 7130 points

Hello Cherry,

The TL431 might work with an optocoupler at 300kHz to 1MHz but it would require a very aggressive compensation network to maximize the TL431's bandwidth. If the TL431's bandwidth is not sufficient, a better solution would be to use a discrete op-amp and voltage reference solution. Here is a 100kHz op-amp design https://www.ti.com/tool/PMP21867 and a 150kHz op-amp design https://www.ti.com/tool/PMP21943.

Best,

Walter

Power management

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TL431: frequency issue