Micro Supervisor

[Rajinder1268]

Hi all,
I have a microcontroller supervisory chip to reset the microcontroller STM32 when the voltage falls below the threshold voltage.
This is only wired to the microcontroller and is open drain with an external pull up.
Is it possible for me to substitute this with a push pull supervisory device?
TLV803
TLV809

I think it may be possible as long as I don't have a wired OR configuration, which I don't. Also I believe the external pull up would need removing?

 

[std_match]

Yes, in this case you can use TLV809 instead of TLV803.
Both can sink 5 mA, so the pull-up resistor can stay if you want.

 

[KlausST]

Hi,

You say STM32 ... but no exact type. There are many different STM32xxx types.

I recommend to read the microcontroller datasheet.

There are devices that have bidirectional (input, open_drain) RESET. In this case connecting a push-pull external supervisory circuit may cause short circuit.

Also some microcontrollers may have a pin with MUXed functions (like RST / GPIO).


Klaus

 

[Rajinder1268]

It is a STM32H7B3Vi
The reset is a bi directional with weak embedded pull up

 

[tepalia02]

You can ask it to the STM forum to be more sure.

 

[KlausST]

Hi,

It is a STM32H7B3Vi
The reset is a bi directional with weak embedded pull up

It says bipolar, but I see no HIGH side driving capability.
Thus the safe way is to use an OpenDrain Supervisor

or if PushPull: either use a schottky diode, or a current limiting resistor in series.

Klaus