LP87725-Q1: RSTOUT open-drain configuration and voltage tolerances

Taylor Gage

Part Number: LP87725-Q1

Tool/software:

I'm working on a design using LP87725-Q1 and would like to use the RSTOUT pin pulled up to 1.8V instead of 3.3V. The RSTOUT pin says it can be open-drain if the internal PU resistor is disabled, which should allow me to do this. What is the default state of that pin with regards to being open-drain vs push pull? And if it's not OD by default, what do I need to do to make that happen? Thank you!

OPN: LP87725110RAGRQ1

11 months ago

0 Ishtiaque Panhwar 11 months ago

TI__Mastermind 20730 points

Hi Taylor,

The correct OPN ; LP87725101RAGRQ1 , there must be typo in the schematic.
nRSTOUT: It is configured as OD with internal PU resistor enabled and polarity is active low.
Internal it is pulled up to 3.3 V level so when you measure the voltage on the pin in inactive condition you would observe 3.3V.
The default state is HIGH meaning there isn't any error pending. If there would be any error which is supposed to cause nRSTOUT to trigger then the signal would be LOW (~0 V).
With this default configurations, you do not need to pull this up to 1.8 V .

Regards,

Ishtiaque

0 Taylor Gage 11 months ago in reply to Ishtiaque Panhwar

TI__Prodigy 200 points

I see. If my goal is to make the RSTOUT signal 1.8V based, could I use the register setting for NRSTOUT_PU_EN to forcibly disconnect the internal pull-up resistor and pull it high to 1.8V externally?

+1 Ishtiaque Panhwar 11 months ago in reply to Taylor Gage

TI__Mastermind 20730 points

Hi Taylor,

Yes It needs to be disconnected then externally connected to 1.8V.

Regards,

Ishtiaque

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LP87725-Q1: RSTOUT open-drain configuration and voltage tolerances