UC2625: Example Design emitter follower

Kyle Newman

Part Number: UC2625

Why does the example design for the uc2625 have an emitter-follower on the high side MOSFET but not the low side of the H bridges? It seems to me that it should have the same setup for both FETs.

over 4 years ago

0 Kyle Newman over 4 years ago

Prodigy 30 points

Edit: I may have figured this out. Is it because the low side output is a true totem-pole, but the high side is not? So power is wasted without the emitter-follower?

0 Matt Hein over 4 years ago in reply to Kyle Newman

TI__Mastermind 21805 points

Hi Kyle,

The low-side switch is a ground referenced NMOS, and can be directly driven by the UC2625. The gate drive is 0V or 10V.

The high-side switch is a PMOS, so the gate drive signal needs to be level shifted up to VMOTOR. The gate drive signal is VMOTOR to VMOTOR - 10V.

Thanks,

Matt

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UC2625: Example Design emitter follower