HI,
How much is the minimum pulse time of UCC28070?Thank you.
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Hi user4599184,
There is no actual minimum pulse width specified for the UCC28070 but in practice you can expect to view minimum
GDA or GDB gate drive pulse widths of about 100nS around the zero crossings
At no load the UCC28070 error amplifier output VAO is disabled when the voltage falls below 0.75V
This turns off GDA,GDB and so prevents an over voltage on the output at no load.
Which means really the answer to your question is that the minimum pulse width is zero.
Regards
John
hi john
thank you for your reply
I have other issue about 28070; we set PFC output bus voltage = 410V; Vin = 288V; load = 40W two channels are interleaved in parallel;
input current come out strange wave ,
as follow pic,
Ch3: input current;
I doubt Vin is too high, then obtain the belo
Ch1:PFCVout; ch2 DRB;ch3 input current ;ch4 input voltage;
We can find Vout > Vin all the time , it explain it is not the root cause ; then we doubt output power is too low, and then we obtain the below wave;
Ch1: DRA; ch2: VAO; ch3: input current ; ch4: Vsense;
We can conclude VAO > 0.75; so it is not root cause;
One question : Vsense > 3V , GDA,GDB is prohibit ?
from pic GDA,GDB is not probit.
Two question: input wave as below pic show on which condition ?
please advise ,thank you very much !
Hello user4599184,
Since your original question was answered please mark this post as closed
You can open a new post if you have a further issue.
Regards
John