LMZ31503: Mosfet for inhibit pin

No specific recommended MOSFET. You can even interface directly to GPIO, as shown in this reference design where INH pin is directly driven by UCD90120A-1 GPIO pins.

Can you tell me what is the range of voltage that is visible at INHIBIT? (To what value this pin is pulled up internally?)

Hi Karthik,

If floated, EN will be pulled up to around 3V. The EN pin itself has abs max rating of 6V which should not be violated.

Taking a brief look at the UCD90320u datasheet section 8.4.5, it appears you should be able to set its GPIO outputs as open-drain, which would be a good option for interfacing to the LMZ31503 INH pin.

Regards,
Kris

But some issues are there involved with it.

1. In your datasheet "https://www.ti.com/lit/ds/symlink/lmz31503.pdf?&ts=1589868780837" in page number 4 It was mentioned that ". A small low leakage (<300 nA) MOSFET is recommended for control" .But UCD90320U have leakage current around 1uA.

2.The VIN used is greater than 10V and in your datasheet in page number 20 it was mentioned that "The Inhibit control has its own internal pull-up to VIN potential"

Can you recommend a mosfet for this usage? Can CSD15380F3 can be used? 

Please clarify and confirm.

Thanks 

Hi Karthik, what questions need further clarification after my response on May 20?

Will you give a better clarity on point number 2 in your previous message.

Karthik, the internal INH pull-up current source goes to an internally generated 3V, not Vin. This can be seen in the the datasheet waveforms Figure 30 and 31.

Thanks