TPSM63606: TPSM63606 TPS25981 Power Sequence

Michael Reilly

Part Number: TPSM63606
Other Parts Discussed in Thread: TPS25981

Hello,

I am planning on using the TPSM63606 DC/DC and would like to power on after TPS25981 eFUSE is enabled and the PG line is asserted. My voltage in is 12V and the output voltage from the DC/DC will be 5V.

My initial plan is to enable the eFUSE based on the the input voltage between 10-14Vdc, one the PGOOD line is enabled I would like to toggle the enable pin on the DC/DC to start it up. However the eFUSE PGOOD is only rated to 5V so cannot tie it to the input voltage. My question is can the DC/DC VCC be used as a voltage source to pull up the PGOOD line. I am unsure if the LDO is fed from the input voltage or output voltage of the DC/DC.

Below is a simple picture. Biggest thing is the VCC needs to be at 5V so the Enable line could be pulled high.

over 1 year ago

+1 Frank De Stasi over 1 year ago

TI__Guru 64395 points

Hello

Unfortunately, the VCC of the DC/DC will not come on until the EN is high. So you have a "chicken-or-egg" situation.

You would need a simple voltage divider between the input voltage and the PG/EN line to limit your PG voltage.

Or a pull-up resistor from your input voltage and a 5-V Zener to ground on the PG/EN line.

Thanks

0 Michael Reilly over 1 year ago in reply to Frank De Stasi

Prodigy 226 points

Okay thanks for the quick response that was my plan B. Glad to find out now rather than later.

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TPSM63606: TPSM63606 TPS25981 Power Sequence