TPS23753APW Pull down resistor of GATE pin line

masahiko shimizu

Other Parts Discussed in Thread: TPS23753A

My customer is using TPS23753APW.
He is worrying that the GATE voltage of FET becomes the unsettled state.

Could you please advice me whether or not pull down resistor should be added on GATE pin line?

If Pull down resistor can add, Could you please advice me resistor value?

Best regards,
Shimizu

over 10 years ago

0 Darwin Fernandez over 10 years ago

TI__Mastermind 41780 points

Hi Shimizu-san,

Can you attach circuit schematic of their design so we can see how the gate drive circuit is implemented?

Typically, a diode bypassing the series resistor works well.

0 masahiko shimizu over 10 years ago in reply to Darwin Fernandez

Guru 11235 points

Hi Darwin-san

Thank you for your support.

Customer doesn't design circuit yet.
Customer will consult datasheet & TI design.
I posted this community to know general advice.

Does "a diode bypassing the series resistor works well." mean "Pull down resistor of GATE line"?

Thanks
Shimizu

0 Darwin Fernandez over 10 years ago in reply to masahiko shimizu

TI__Mastermind 41780 points

Hi Shimizu-san,
Typically there is series resistor on the primary gate. This acts to slow the FET turn on so as to have proper timing between the primary and secondary FET (which has a snubber). Sometimes the resistor is increased which causes slower on and consequently slower turn off (which is undesired). Therefore, a diode with cathode facing the gate pin of the IC and the anode facing the gate of the primary FET is used in parallel with the resistor to have a slower turn on, and fast turn off.

0 masahiko shimizu over 10 years ago in reply to Darwin Fernandez

Guru 11235 points

Thank you for your advice.

Please see the attached file.

Pull down resistor means the part of red circle in file.

Is such processing generally performed in PoE?

The purpose of pull-down is to preventing the unsettled state of the FET GATE voltage .

Thanks

Shimizu

pulldown resistor.pptx

0 Darwin Fernandez over 10 years ago in reply to masahiko shimizu

TI__Mastermind 41780 points

Shimizu-san,

The TPS23753A can good pull down characteristic so I don't typically see pull down resistor on gate pin.

0 masahiko shimizu over 10 years ago in reply to Darwin Fernandez

Guru 11235 points

Hi Darwin-san

Thank you for your support.
I understood.

Thanks
Shimizu

Power management

Power management forum

TPS23753APW Pull down resistor of GATE pin line