DER-802 Not Working
Hi,
We are reproducing the DER-802 circuitry design. When plugged to 230VAC power at 50Hz, the output voltage gets 5V with no load. However, when a load starts to demand current, it stops working at 50mA and the InnoSwitch3-Pro detachs the output.
I attach the schematic and scilloscope signals from Output (When it turns-off) and Forward pin voltages.
Looking forward to receiving feedback.
Best Regards,
댓글
Hi,
Yes we removed the R44 and R33 (current sensing resistors) and shorted these pins, and the same thing happens. We also have removed the R21, which is in charge of applying an offset for the current sense and neither works. The outptut gets disconnected and the behaviour is the same.
Best Regards,
Hi Aitor,
To disable current sense offset, R21 (10ohms) must be present and R20 (324k) must be removed.
Can you verify again with that configuration above and R44 and R33 present while IS-GND pins on the IC are shorted?
Load current will flow through R44 and R33 in the power path of your layout but the InnoSwitch3-Pro IC will not sense any current since IS-GND pins are shorted together.
Regards,
PI-Spark
Hi,
We have verified the design with the configuration you requested and still is not working. We have tested it with R44 and R33 present, R21 present, R20 removed and IS and Ground pins shorted in the chip.
Best Regards,
Aitor.
It may also be a good idea to check to see if the transformer is properly phased. For a positive Vout, the drain of the synchronous rectifier should go positive when the primary switch is on.. On the primary side, the output of the bias winding should go negative when the primary switch is on (measure at the anode of the bias rectifier). If either of these windings are mis-phased, you can encounter the trouble described in the first post.
Hi Wrench,
Thank you so much!!!. Finally we solved the issue. The problem was on the secondary winding of the transformer. As you said the Windings were mis-pashed.
Thank you so much again.
Best Regards,
Aitor.
Hi Aitor,
Thank you for using our DER-802 USB PD adapter design.
Can you verify if the behavior is the same when you temporarily short the IS and GND pins of the InnoSwitch3-Pro?
The behavior you are describing is similar to when the resistance seen by IS-GND is much higher than the needed current sensing resistance (e.g. two 110mohms current sense resistors were in parallel instead of 9mohm parallel 100mohm).
Let us know if you can draw full load when IS-GND pins are shorted and we can continue from there.
Regards,
PI-Spark