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SN74LVC1G02: Drive Nch FET

Michiaki Tanii
Expert 4610 points
Part Number: SN74LVC1G02
Other Parts Discussed in Thread: UCC27517

Hello team,

 

Our customer would like to drive Nch FET from output SN74LVC1G02 directly.

Here is the specification.

 

  • Power supply        5V
  • SW frequency        100kHz
  • FET
  • Ciss           1.4nF
  • Gate resistor   1.3ohm
  • VGS            1.0V – 2.0V

 

They estimate max output current from gate of FET to output of logic will be 5V / 17ohm = 294mA since the output impedance of logic could be calculated ROH = 22ohm and ROL = 17ohm.

The time flowing current at 294mA will be around 5u sec.

 

I believe the above operation is over absolute maximum ratings, so cannot be acceptable.

If you have any proposal, please let me know.

 

Thank you and best regards,

Michiaki

  • 0
    Guru 316690 points

    If you want to drive such a high capacitance from a logic device, you have to add a series resistor to limit the current (which increases the switching time). To increase the drive strength, combine the outputs of multiple gates (but with 50 mA per gate, that would be unwieldy).

    It would be possible to use a gate driver like the UCC27517.