UCC28780: IPWML(H) of PWML,PWMH

Yi Dou

Part Number: UCC28780

Hi E2E,

1. Would like to learn why at high/low level of below pins, the load current is negative/positive? Typical high means source, positive, and low means sink, negative.

What's more, I think the name is missed for current definition, we should have IPWML(H), IPWMH(H), the "(H)" should mean reference direction of source/sink current, I guess.

2. The maximum source/sink current is ~1mA, right？Could I use 0.5V/1mA=50Ohm to estimate the pull-up and pull-down resistance inside PWM output stage?

3. The test condition for Trise/Tfall is with 10pF Cload, if no load connected to PWM, what is the rise/fall time? Will it differ much?

Let me know if you have any comments. thanks!

over 4 years ago

0 Mike O' over 4 years ago

TI__Guru* 85556 points

Hello,

I have forwarded this to the appropriate applications engineer so he can help you answer your questions?

Regards,

0 Yi Dou over 4 years ago in reply to Mike O'

Intellectual 545 points

Thanks, looking forward to your kind answers!

0 Yi Dou over 4 years ago in reply to Mike O'

Intellectual 545 points

HI, are there any updates?

0 Yi Dou over 4 years ago in reply to Mike O'

Intellectual 545 points

Hi, could I get any response from TI?

0 Jaden Ning over 4 years ago in reply to Yi Dou

TI__Expert 7080 points

Hi Yi Dou,

Thanks for your interesting in TI's part and sorry for the later reply.

Actually , almost all of your questions are related to controller internal circuit design parameters . it should can be answered by designers , but Application engineer are responsible for the E2E reply . So may I ask what is the issue or problem you are facing when you use this part ?

0 Yi Dou over 4 years ago in reply to Jaden Ning

Intellectual 545 points

Although TI recommended specific isolator/driver IC connected to PWM, I still would like to fully evaluate the PWM I/O feature of ucc28780.

Because you know for different FETs in the market, gate-source or PWM input features are totally different among different vendors. That's why making it clear of I/O feature is so important for identifying delay time of PWM transition, for converter modeling up to MHz.

0 Jaden Ning over 4 years ago in reply to Yi Dou

TI__Expert 7080 points

Hi Yi Dou,

Totally agree with you delay time of PWM transition is important for high switching frequency converter. based our experience , the turn on delay of isolator / gate driver is more sensitive than UCC28780 I/O rise/down tolerance . since the better gate driver delay in the market is ~25ns while common delay is ~100ns . So choose small delay isolator/gate driver in your high frequency design.

Thanks.

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UCC28780: IPWML(H) of PWML,PWMH