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Tool/software:
Hi!
We are using the SN6507DGQR with the Wurth 750319691 transformer in one of our designs. The diodes and snubber is replaced else schematics as below. Input voltage is 12 V.
We can see a high temperature rise (>15 degrees) in the transformer even with no load. Also on the EVB (SN6507DGQEVM) with the Wurth 750319691 transformer we see the same results.
Any ideas?
Thanks!
Hi Bo,
Thank you for reaching out and sharing the schematic.
The schematic mostly looks good. Can you please confirm if the resistor R111 at DC pin is populated or not populated? If the DC control not used then the circuit should work fine but if DC is indeed connected to a resistor then the transformer needs to be changed to one with higher turns-ratio to generate 12V with 25% duty cycle.
The possible reason for high temperature is the high switching frequency (1MHz), I recommend bringing down the frequency to a lower value to see temperatures come down. Thanks.
Regards,
Koteshwar Rao
Hi!
Thanks for quick reply!
Sorry it's not populated.
I have done some more measurements and the current consumption unloaded seems to be around 30 mA at 12 V. When i reduce the switching frequency the consumption seems rising. So maybe i need to try another transformer to support 12 V at lower switching frequency? I will do some more investigations.
Regards
Bo Stångberg
Hi Bo Stångberg,
Thanks for the update.
Could you please confirm what frequency did you reduce to?
I expect the existing transformer to work fine upto 400kHz. Let me know, thanks.
Regards,
Koteshwar Rao
Hi!
I tried with 400 kHz but only a small decrease in current consumption. I will try with a different transformer and compare to the SN6507DGQEVM evaluation board. Signals seems to look fine with minimal ringing.
Regards,
Bo Stångberg