LM5069 - pulling GATE pin to GND for fast turn-off

Lucas H. Sturnfield

Other Parts Discussed in Thread: LM5069

Hi,

I am working to develop a circuit which will speed up the turn-off time of a LM5069 IC, which is being used to drive 4x parallel NFETs. My working solution is to use a signal NFET and pull the GATE node directly to GND. The "....kill" signal is used to rapidly terminate current flow.

Is there a potential to damage the IC (particularly the charge pump) by doing this? Should I limit the current to GND, and if so, to what amount?

I've attached a partial schematic which shows the circuit referenced.

Lucas

over 9 years ago

0 Alex Triano over 9 years ago

TI__Genius 12510 points

Hi Lucas,

I'm discussing with our team, will get back to you tomorrow.

Thanks,
Alex

0 Alex Triano over 9 years ago in reply to Alex Triano

TI__Genius 12510 points

Hi Lucas,

We believe the charge pump should be ok, however we are concerned this may violate the Vgs rating of Q2 in the schematic you provided.

An implementation we would think is a bit safer would be:

The zener would protect the Vgs rating, the 5nF and 100ohm cap would allow a fast turn on of the PFET (fast discharge), but would limit the DC current dissipation.

Thanks!

Alex

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LM5069 - pulling GATE pin to GND for fast turn-off