universal input forward design
Hi.. I AM WORKING AS A POWER SUPPLY DESIGNER.I HAVE BEEN USING PI DEVICES SINCE 10 YEARS AND SOME OF MY DESIGN ARE AT PRODUCTION TOO. AT THIS TIME I NEED TO KNOW WHETHER WE CAN DESIGN A UNIVERSAL INPUT POWER SUPPLY USING TOPGX DEVICE FOR A 70 WATTS DESIGN. THE OUTPUT IS 6.4V@12AMPS. IF YES PLEASE PROVIDE THE DETAILS OF TRANSFORMER AND PRIMARY CIRCUITS. IF NO PLEASE CONFIRM WHETHER THE SAME CAN DE DONE IN FLYBACK CONFIGURATION.THE POWER SUPPLY IS A DESK TOP ADAPTOR AND IT IS TO BE WORKED AT FULL RATED LOAD FOR MOST OF THE TIME. I HAD DONE ONE IN FORWARD TOPOLOGY USING TOPGX AND THE SAME IS WORKING FROM 140 TO 260 VAC AND BELOW 140 IT SEEMS THE BIAS IS GOING LOW. CAN WE PUT ANY LINEAR REGULATOR IN THE BIAS WINDING AR CAN WE PROVIDE VOLTAGE FROM ANOTHER SOURCE FOR THE SAME.
CAN ANY ONE RESPOND TO THIS ASAP AS WE NEED TO START THE DESIGN SOON TO SUBMIT PROTO TO OUR CUSTOMER.
THANKS
SIJU
Comments
YES I UNDERSTAND THAT FLYBACK IS NOT A GOOD CHOICE FOR THIS DESIGN. I DO NOT HAVE A PFC FRONT END AS THE SMAE PSU IS ONLY 70 WATTS MAX. ASLO PLEASE MAKE CLEAR WHY TOPGX IS NOT GOOD TO WORK IN FORWARD TOPOLOGY. (I REMEMBER YOUR PC POWER SUPPLY EP-12 WORKING FINE IN THE FORWARD TIPOLOGY). ALSO AS I SAID EARLIER EVEN I HAD MADE A SMAPLE WITH TOPGX WORKING IN UNIVERSAL REANGE IN FORWARD TOPOLOGY WITH AN EFFICIENCY OF AROUND 80% IN THE ENTIRE RANGE. THE ONLY PROBLEM THAT I AM FACING IS WITH THE BIAS VOLTAGE.PLEASE SUGEST THAT WHETHER WE CAN PROVIDE AN EXTERNAL BIAS SUPPLY (USING TINY OR LINK) SO THAT THE PSU CAN WORK WELL IN THE ENTIRE RANGE.
THANKS
SIJULAL
TOP-GX needs to be designed very carefully for a universal input voltage range. The duty cycle reduction for this design has to work exactly right otherwise you either run into the risk of saturating (not reseting) the transformer or dropping out of regulation...
Thats one of the main reasons we have stopped recommending TOP-GX for forward converters.
HI THANKS FOR THE INFORMATION. THEN PLEASE MAKE CLEAR WHETHER WE CAN USE THE SAME IF WE HAVE A PFS FRONT END.
Yes you can with a PFC front end. However we do not have support for the forward topology using TOPSwitch-GX in PIXls.
HI, YES I HAVE PIXLs THAT SUPPORT FORWARD TOPOLOGY USING TOPSWITCH-GX AND I HAVE DONE THE CURRENT DESIGN IN THAT TOO (I THINK VERSION 5).ALSO PLEASE INFORM WHETHER YOU CAN HELP BY VERFYING THE SAID POWER SUPPLY DESIGN WHICH I HAVE DONE AND SEND THE SAME BACK IF I AM SENDING IT TO YOU AND COMMENT FOR THE SAME.IF SO I WILL BE ALSO MUCH CONFIDENT IN MY DESIGN TOO. THE POWER SUPPLY IS NOW WORKING AT UNIVERSAL RANGE AT A EFFICIENCY OF 82% WITH AN OUTPUT LOAD OF 6.4AMPS AT 10AMPS.
at 12 A I would advise you to not try the Flyback topology. That being said the forward topology does not lend itself very well to universal input... Do you have a front end PFC to boost the input voltage to 400V?
Also we do not recommend the TOP-GX family for forward topology. Quite honestly I don't recommend the you consider PI for this application.