TPS92515HV-Q1: Using IADJ pin to soft-start the turn-on

RoyChen776

Prodigy 240 points

Part Number: TPS92515HV-Q1

Hello, I am using TPS92515HV-Q1 for LED driving.

I needed to use soft-start for my applications.

Could you let me know, how many internal discharge resistance in the IADJ pin?

Thanks.

over 6 years ago

0 Irwin Nederbragt over 6 years ago

TI__Mastermind 28655 points

Hello,

What time constant are you looking at using? It is an input to an op-amp so the impedance is high. Also see 8.3.7.2 in the datasheet about the transition if you are going to full clamp voltage on page 15. The clamp transition is done in a way that a soft-start circuit works so it doesn't behave like a zener clamp but transitions to an internal clamp allowing the use of high impedance soft-start. I'm asking about more information on the impedance of that pin.

Best Regards,

0 Irwin Nederbragt over 6 years ago in reply to Irwin Nederbragt

TI__Mastermind 28655 points

Hello,

The impedance is high enough you should be able to place an RC filter on this pin for you application. If you can use 100 Kohm it will be accurate, 1M will probably work as well. And once in runs into the clamp it should function as if the pin were pulled high.

Best Regards,

0 RoyChen776 over 6 years ago in reply to Irwin Nederbragt

Prodigy 240 points

Hi Irwin Nederbragt,
Okay, I understand it now.
Thanks for your support.

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TPS92515HV-Q1: Using IADJ pin to soft-start the turn-on