TPS53353: TPS53353'EN pin incorrect

user1359349

Part Number: TPS53353
Other Parts Discussed in Thread: LM3881, TPS53355

I'm using the TPS53353 now,currently i have several questions :

In my design,the EN pin of TPS53353 is controlled by the LM3881 which have four flag pin,because the output of LM3881 is open drain, so the flag pin pulled up to 3v3 use 100k resistor,but when i test the EN pin level ,i found that it was 3.5V(the pull up voltage is 3.3V),so i have remove the serial resistor R247,and the LM3881 output is 3V3(it's ok),and the EN pin of TPS53353 is 3.8V,when i remove the pull up resistor R135 of TPS53353'EN pin,then the EN pin is 5.9V,
When I installed a new TPS53353,and the EN pin of TPS53353 is disconnected,the voltage is still 5.9V.

disconnect between LM3881 and tps53353(remove R247)

remove pull up resistor R135

the EN pin of TPS53353 disconnected ,but it's still 5.9V

My question is :
1)what have caused the voltage of the EN pin so high
2)Please review my design. Is there any error?
3)because we have delivered for customer a lot of ,is there any risk

thanks!

over 4 years ago

0 user1359349 over 4 years ago

Intellectual 450 points

Part Number: TPS53353

Tps53353'EN pin incorrect

0 Kris F over 4 years ago in reply to user1359349

TI__Genius 17905 points

Hi,

This related thread may have the answers you are looking for: https://e2e.ti.com/support/power-management/f/power-management-forum/848132/tps53353-en-pin-strange-behaviour/3141737#3141737

Since the EN pin is still below the recommended max of 6.5V and abs max of 7V, I do not see any risk in the design.

0 user1359349 over 4 years ago in reply to Kris F

Intellectual 450 points

sir

0 user1359349 over 4 years ago in reply to Kris F

Intellectual 450 points

sir

0 user1359349 over 4 years ago in reply to Kris F

Intellectual 450 points

sir

0 user1359349 over 4 years ago in reply to Kris F

Intellectual 450 points

sir

0 user1359349 over 4 years ago in reply to Kris F

Intellectual 450 points

thanks for your reply,because the EN pin is controlled by LM3881, is LM3881 work reliable in this condition,in addtion,the EN pin of TPS5335 is pull up to 3V3,why does it become to 5V?is there a pull up resistor in the tps53353?

0 Lishuang Zhao over 4 years ago in reply to user1359349

TI__Expert 7500 points

Hi,

Kris will feedback to you on Monday.

Thanks,

Lishuang

0 user1359349 over 4 years ago in reply to Lishuang Zhao

Intellectual 450 points

What feedback do you have? We have delivered a lot to customers. Are there any risks? I look forward to your reply，thank you very much!

0 Kris F over 4 years ago in reply to user1359349

TI__Genius 17905 points

With the intended pull-up resistor populated, the voltage is 3.5V, which is within the recommended ratings of both LM3881 and TPS53355. I do not see any risk.

As mentioned in the link I shared before, there is a pull up current when the part is enabled. The linked thread mentions it can be up to 5uA, but on the bench on one EVM, I see a pull-up current of around 2uA. 2uA would explain why you see 3.5V, because the 2uA going through your 100kohm pull-up resistor will add 200mV as the current flows into the pull-up resistor. So long as your 3.3V supply is able to sink this minimal current, I do not see any issue.

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TPS53353: TPS53353'EN pin incorrect