TPS62261-Q1: 1．8V at EM when power is off

Masatoshi Oguri

Part Number: TPS62261-Q1

Hello,

Do you think it is OK if 1.8V is applied to VOUT (FB and SW pins) when the device power is off? The customer is considering applying 1.8V to the downstream circuit to activate it while the entire system power is off. I think it is OK for SW, but for FB the maximum rating is not defined.

Thank you.

Regards,

Oguri (TIJ automotive FAE)

over 2 years ago

0 Tanvee over 2 years ago

TI__Genius 13440 points

Hi Oguri-san,

It is not recommended because it is fixed frequency converter and it might lead to excessive reverse current at startup and might damage low side FET and the device gets damaged. Please take a look for following app note for more details.

https://www.ti.com/lit/an/slua962/slua962.pdf?ts=1636533426864&ref_url=https%253A%252F%252Fwww.google.com%252F

Best regards,

Tanvee

0 Masatoshi Oguri over 2 years ago in reply to Tanvee

TI__Expert 4780 points

Hi Tanvee,

Thank you for the prompt feedback. But it is not a concern, because there is no chance for the device to start up with VOUT pre-biased. The condition of 1.8V at VOUT is only happens at lab to put some tweak on the software in the downstream MCU.

My concern is, if a device damage is expected with FB pin biased at VIN (0V) + 1.8V because some other pins are rated at VIN + 0.3V as the maximum. I would like to know the maximum voltage allowed for FB is which of VIN+0.3 and 7V.

Regards,

Oguri

+1 Tanvee over 2 years ago in reply to Masatoshi Oguri

TI__Genius 13440 points

Hi Oguri-san,

Thanks for explanation.

Feedback pin voltage should not go above 0.6V as specified in the data sheet. This pin can not handle higher voltage and higher voltage can damage the internal circuit.

Best regards,

Tanvee

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TPS62261-Q1: 1．8V at EM when power is off