TPS51200: shut down sequence

Given Ding

Part Number: TPS51200

Hi team,

just want to check if there is shut down sequence requirement.

It seems LDOIN should shut down before 3.3Vin. Does it mean that " LDOIN need to fully shut down then 3.3Vin shut down " or " if LDOIN begin to shut down, then 3.3VIN can shut down " ? Thanks.

BRs

Given

over 2 years ago

+1 James Steenbock over 2 years ago

TI__Mastermind 23030 points

Hi Given,

Based on the datasheet Figure 19 and 20, it is recommended to fully ramp down VLDOIN before the 3.3V input begins to power down.

Regards,

James

0 Given Ding over 2 years ago in reply to James Steenbock

TI__Genius 10585 points

Hi James，

Thanks for your reply.

What is the risk if 3.3V begin to power down when VLDOIN does not fully ramp down?

BRs

Given

+1 James Steenbock over 2 years ago in reply to Given Ding

TI__Mastermind 23030 points

Hi Given,

I believe this power down sequence makes sure that the high side FET does not pass through VLDOIN while the part is powering off. The goal is to avoid any chance of the 3.3V input being directly fed to the output due to changes in the FET biasing.

There are other internal blocks and power down steps in the sequence that also protect against this event as well so it may not be absolutely essential to power down VLDOIN fully before the 3.3V VIN but it's safer to do so.

Regards,

James

Power management

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TPS51200: shut down sequence