UCC24612: UCC24612 : switch turn off early

user5293374

Prodigy 20 points

Part Number: UCC24612
Other Parts Discussed in Thread: UCC28780,

I use ucc28780 with ucc24612 to build ACF

Here is a question about SR turn off early when ABM to AAM but when load goes heavier the situation disappear

if you have any idea about it I will very appreciate

thanks

over 6 years ago

0 Kuan Wei Chen (Kevin Chen) over 6 years ago

TI__Genius 9710 points

Hi,

Thanks for using TI's products in your design.

If you want to solve this turn off issue, is related to your circuit design instead of UCC24612.

The reason of this region is because voltage on the clamp capacitor drop too low.

Here are some suggestion for you:

1.Increase Clamp capacitor

2.Longer Tz, which mean longer dead-time between PWMH falling edge and PWML rising edge

3.Larger Rds for high side switch, which will cause smaller Coss.

If you want to solve the proportional gate drive, you can change to higher Rdson for SR FET. By this kind of control method, smaller Rdson didn't gurantee higher efficiency.

Best Regards

Kevin

0 user5293374 over 6 years ago in reply to Kuan Wei Chen (Kevin Chen)

Prodigy 20 points

I try to longer Tz by external resistance but this situation isn't improve .

0 Kuan Wei Chen (Kevin Chen) over 6 years ago in reply to user5293374

TI__Genius 9710 points

Hi,

Can you also help me to increase the clamp cap to check the result?

You can use double of the value.

Best Regards

Kevin

Power management

Power management forum

UCC24612: UCC24612 : switch turn off early