Der 286 Problem at no load
Dear Sir,
I found many problems with der 286.
We assembled it as per given scematic. It works at 30V 1A.
But at no load condition it consumes 8W and after some time output Capacitor C3 C4 will burn.
we check no load voltage is comes out 70V and the capacitor rating is 50V so we change to 100V capacitor but then diode D1 will burn out at no load condition.
Please suggest will this driver works ok on no load condition or any have some design problem.
Please reply ASAP
With best regards ,
Ajay Sharma
Comments
Dear Sir,
I checked Q2,Q3,R18, R17, C12, VR3, R13, C10, D7. as suggest in the der 286 design all component are same but the output capacitors will damage at no load condition. Please suggest what changes required to protect this driver at no load condition. This driver consumes 8W at no load condition which is very high and output voltage is 70VDC which is also high. Please check this design by making some samples May be this design have some problem.
With best regards,
Ajay Sharma
Hi Sharma,
Please probe the following points and monitor the following upon load disconnection or start-up at no-load.
Ch1: Vout
Ch2: Cathode of D7 (DER 286), voltage at the bias signal to OVP circuit.
Ch3: BP pin
DER 286 has benn verified for no-load, refer to figure 31 and 32.
Please send your schematic and waveform.
As for direct technical support, please contact the following loacal sales in yoour area.
http://www.powerint.com/en/company/sales-information/worldwide-sales-support-locations
Regards
Dear Sir,
We put a capaacitor on q3 lags sothat no load problem is resolved. But now IC will burn after 1 minute or 15 Minute. Now no load voltage is 55V which is ok with 50V output capacitor. Ic will burn at load condition. Can you please suggest a solution why IC is burn in load condition? If we put capacitor of 1 nf on q3 lags is it effect on IC or some thing else reason?
Please suggest some solution for this driver.
With best regards,
Jai
Hi Jai,
Please probe the drain voltage during no-load. Please make sure it does not exceed the device rating.
Which pin(Q3) did you put the capacitor?
The original circuit will work without problem, please recheck the layout or pin assignment of transistor used. Normally transistors have different pin assignment, please rechectk the datasheet.
Regards,
PI-Jono
Dear Sir,
We put a capacitor between base and emitter so noload problem is resolved but IC will burn after 5 to 15 minutes. i will check again the device rating and drain voltage will share with you results ASAP.
With best regards,
Jai
Dear Sir,
We put a capacitor between base and emitter so noload problem is resolved but IC will burn after 5 to 15 minutes.Device rating is 700V and we have below 350V at drain pin.
With best regards,
Jai
Hi Jai,
During no load the output voltage should be close to zero. Please measure drain to source pin during no-load. You should not see any switching waveform.
We tried your test over here but no failure after 3 hours continuous no-load test for DER286.
It will be good if you can send us some waveforms for further analysis. Please send also your schematic so we can check the values of components used. Send us also the data sheet of your transformer.
Regards,
PI-Jono
Dear Sir,
Attached please find below link for DER 286 Scheatic , Bom and Transformer datasheet which we used.
http://www.sendspace.com/file/fw349o
Can we send you sample for test or we handover sample to your Indian (delhi) FAE and they deliver to you for test.
Please suggest.
With best regards,
Jai
Please contact your local FAE for support. You may send your board to the FAE and if they are unable to find out what's causing your board problem, they can request support from PI HQ.
Dear Sir,
Please suggest any other design with similar specification as in DER 286.
With best regards,
Jai
Hi,
You can select the reference designs from this link:
http://www.powerint.com/en/design-support/parametric-search#6500
By the way, you can attach your schematic in this forum so that we can review. We are having difficulty to open you schematic in another site. PDF would be better.
Below are the sales support, you can call and contact the FAE for direct support in your region.
http://www.powerint.com/en/company/sales-information/worldwide-sales-support-locations
Regards,
PI-Jono
Hi Ajay,
Please recheck the OVP protection. DER-386 has no load protection through OVP latch. The components for OVP are D7(make sure to connect right after the bias winding for fast response), C10, R13,VR3(dictates the threshold for latch), C12, R17, Q3, Q2, and R18.
Through OVP latch you can protect the output capacitor so you can maintain 50V or 63V capacitor.
Regards,
PI