Part Number: UCC28019A
My client tested the UCC28019A to be noisy at no load.
Test conditions are as follows:
VAC 220VAC/ no load.
After measuring the prototype I found to have audio noise, the VCOMP voltage is 1.4V lower than the normal (no audio noise) prototype.( normal VCOMP :1.5~1.9V),
I have added 1.5M ohm between VCC and ICOMP, which can solve the test problem. I have tried to adjust the ICOMP and VCOMP parameters and can't solve it. Is there any way to eliminate the noise of the UCC28019A by adding 1.5Mohm?
Hello Hsu cheng,
The attached document discusses this issue about how to eliminate audible noise at no load with the UCC28019A.
JohnUCC28019A to Avoid Audible Noise.pdf
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
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In reply to John Griffin1:
This document has been provided to my customers before, because the solution in the file needs to increase the resistance, the customer can not agree, is there any other way to improve?
In reply to Hsu cheng:
This is the recommended method for alleviating no load audible noise issues.
Why does your customer not agrees with this fix?
This case is an MP model, the customer will not update the PCB Layout, only the peripheral part value can be modified.
Audible noise is created by the controller missing pulses during the pwm cycle. The controller goes into an asynchronous mode followed by a large pulse width to the gate drive. Adding a small offset signal to ICOMP eliminates this.
There are very few other options available to eliminate any no load noise issue.
You can either:
(1) Add a small resistor from VCC to ICOMP
(2) Increase the minimum load to a value that eliminates this effect
(3) Build a low noise inductor and a better mechanical enclosure
There are no other options
Ok, there is no data to prove that there is a problem with the customer design, it is the noise caused by the UCC28019A ICOMP error.
I am going to close this post since there has been no update in over 2 weeks.
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