TPS3420: Internal structure of PBx inputs

Hi user,

The TPS3420 has NMOS based inputs that do not require pullup resistors. For that configuration, I recommend using the TPS3421.

Thanks,
Abhinav.

I need TPS3420 version because i want that reset pulse will stay active until on of the buttons is released.

So, is only option to put MOSFET N-type infront of PBx inputs (open drain configuration) and use it to drive button press down from differrent voltage level?

In case of external pullups to VCC, what is the penalty?

Hi user,

I believe the only option is as you mentioned. In the case of pulling up a push-pull to Vcc, I believe you will have issues with functionality and notice leakage on this part.

Thanks,
Abhinav.

I have replaced TPS3420 on TPS3421EGEVM evaluation board, and also removed resistors R1 and R2 as instructed on manual.

When powered, RSTN goes high and after 7,5seconds it will stay down for until powered off. I did not even press buttons. Voltage at PBx input is zero.

Behaviour is a bit confusing to me. Inputs dont need anything to drive "high"?

Marko

Marko,

Good to see that the circuit works. If you don't mind, can you share the working schematic?

Thanks,
Abhinav.