UCC27201A: Behavior at 100% Duty

Ryu Yamashita

Part Number: UCC27201A
Other Parts Discussed in Thread: LM5060

Hi team,

I was aware it was for a half-bridge configuration, but I thought that by using only the pins on the high-side, I could simply drive the high-side N-channel MOSFET.
However, with our continuously powered N-channel MOSFET, a phenomenon occurred where the gate voltage dropped at 200ms intervals (varying depending on the current value in the power circuit), causing the on-resistance to increase.
After changing to the LM5060, we confirmed that intermittent operation no longer occurs. What differences exist in the internal circuitry?

Best Regards,
Ryu.

8 months ago

+1 Amy Wozniak 8 months ago

TI__Expert 6310 points

Hi Ryu,

Please read the following FAQ for information on using half-bridge gate drivers with 100% duty cycle. [FAQ] Can TI's non-isolated half bridge drivers be used in 100% duty cycle applications?

Our non-isolated half bridge driver cannot be used in a 100% duty cycle configuration without externally biasing the high side. This is because our drivers do not bias the high side internally. Instead, the high side is biased by a large bootstrap capacitor, which charges when the low side switches.

The LM5060 has a charge pump to internally to keep the high side switch on with a 100% duty cycle.

Best,

Amy

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UCC27201A: Behavior at 100% Duty