UC/3/4/5. UC/3/4/5. October CURRENT MODE PWM ZED FOR OFF LINE AND DC TO DC. CONVERTERS. UC Switching Controllers are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for UC Switching Controllers. Texas Instruments UC Series Switching Controllers are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas.

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I’ll try to respond as soon as I can. Hello Sulyn, It is an interesting problem; the AUX voltage is actually a little higher during short-circuit conditions than when normal.

Meanwhile, since this is an industry-wide forum, I invite other viewers, inside and outside of TI, who may already have a solution to offer their advice on this matter. In reply to Ulrich Uv2842. Mar 10, 8: Trademarks Privacy Policy Terms of Use.

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When we measure the output of auxiliary winding output voltage and Vaux, it seems the Vaux is not pulled down due to that these is leakage inductance, so it seems Vaux is not pulled down.


Below are two waveform with normal load status and 5V output load shorted to GND: Mar 10, 1: This can allow a smaller R-C snubber to be used at AUX to dampen the remaining ringing and reduce standby power.

Your customer can test this idea 2 ways: So based on above information and description, can you or anyone give a available solution to realize Hiccup mode with our UC? If so, that is what customer wanted! Mar 12, 7: More detailed schematic as below for your check:.

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However the standby current will increase about 2W which can’t be accepted by customer. The newly created question will be automatically linked to this question.

I suspect that the current sense R-C filter is delaying the peak signal too long and allowing a high primary peak current during the short condition. Mentions Tags More Cancel. This seems to be a long on-time for a protection condition.

We are glad that we were able to resolve this issue, and will uc842 proceed to close this thread. Hello Sulyn, I have a few thoughts about this, although not a definitive answer. Maybe that will snub the excess ringing, but D2 will block any drop on the Vaux rail and T1 will stay off.


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Menu Search through millions of questions and answers User. The simple the solution the better, thanks a lot!

UC2842: How to realize Hiccup mode by using UC2842 in fly-back topology?

Ask a related question Ask a new question. Best regards, Sulyn Zhang. If this filter can be made smaller, the Ipk will be lower and maybe the leakage inductance ringing will be smaller, too. Mar 10, 3: In reply to Ulrich Goerke: However, the reality is cruel Regards, Ulrich Locked Cancel Do you have another question?

I suspect that putting the R-C across the AUX diode D2 allows it to briefly pull down the Vaux rail every switching cycle during normal mode and those perturbations might be triggering the start-up transistor T1 to briefly conduct each cycle.

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