PTN78060W: Applying 5V at output pins with Input Pin Floating

N S

Part Number: PTN78060W

I am planning to use PTN78060W in one of our boards. The board would be powered from either 24VDC or 5VDC. So it has 3Way Power connector (terminal block)

For 24VDC Vin case

the positive of 24Vin goes straight to Vin Pin of PTN78060W that steps it down to 5V output which subsequently goes into the input of couple of more voltage regulators with 3.3V & 2V output. So no issues here

For 5VDC Vin case:

The positive of 5V goes to the track which is connected to the output pin of PTN78060W

We would not have 24V & 5V at the same time at Input. It would be one or the other

The question is that would it be safe for PTN78060W to be operated like this i.e., 5V applied at its output with Input floating for the case when our input voltage is 5V.

See attached rough diagram of the setup.

over 5 years ago

0 Jimmy Hua over 5 years ago

TI__Mastermind 47060 points

Hi NS,

I am actively looking at this and will get back to you after taking into some application considerations.

Regards,
Jimmy

0 Jimmy Hua over 5 years ago in reply to Jimmy Hua

TI__Mastermind 47060 points

Hi NS,
If you are placing an external voltage source on Vout pin, then that pin would try to sink current. I'd recommend having a blocking diode to protect against reverse current into the output pin. There may be some parasitic path through the Vout pin to ground that could damage the internal circuitry.

Regards,
Jimmy

0 N S over 5 years ago in reply to Jimmy Hua

Intellectual 365 points

Thanks for the confirmation. I shall use a blocking diode then :)

Power management

Power management forum

PTN78060W: Applying 5V at output pins with Input Pin Floating