TPS2419 with 3 FETs, Delayed turn on problem

Jin Kim

Intellectual 430 points

Other Parts Discussed in Thread: TPS2419

Hi,

I have a problem with TPS2419.

When we are using 3 FETs with 1 TPS2419, The FETs are turned on delayed time is more than 3 second.

So, If you can advise for me to improve this phenomenon. Also how many FETs may I use at 1 TPS2419.

When I use only 2-FETs with 1 TPS2419, It is working well.

We are using recommended FET(CSD16401)

Please answer me.

And here is our circuit and turn on timing

over 13 years ago

0 Jin Kim over 13 years ago

Intellectual 430 points

Hi.

I hope to see an answer.

Why don't you answer about my question.

0 Eric Wright over 13 years ago in reply to Jin Kim

TI__Mastermind 42795 points

For proper circuit operation, the MOSFET sources should connect to "A" and the drains to "C"

0 Jin Kim over 13 years ago in reply to Eric Wright

Intellectual 430 points

Thank you for your answer.

But, we already tested with MOSFET sources connect to "A" and the drains to "C"

Our schematic is wrong at this point.

So, Do you have another idea for this problem?

I hope to see your quick answer.

Thanks.

0 Eric Wright over 13 years ago in reply to Jin Kim

TI__Mastermind 42795 points

We need more information at this point. Please provide oscilloscope shots of start up showing A, C, GATE, EN nodes. A and C have internal UVLO of 2.5V (max) so if 3.4V is not stable then start up will be abnormal. EN threshold is crossed when "A" is at ~2.7V. If there is noise on EN due to unstable 3.4V then start up may be erratic as well.

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TPS2419 with 3 FETs, Delayed turn on problem