XYS3580 DC Buck Boost Converter with a nasty overshoot

[Paul Moir]

https://www.ebay.com/itm/XYS3580-DC-DC-Buck-Boost-Converter-CC-CV-0-6-36V-5A-Power-Module-Adjustable-/133452975324

I guess I was looking for the RD DPH3205 but missed.  This similar looking and handy buck-boost converter has some interesting features and seems a little focused on battery charging.  Turn-on characteristics were fine, but when I looked at recovery after disconnecting a load, there was a significant and prolonged overshoot which greatly limits the use of this supply.

These were taken with a 9V supply.  Increasing it to 20V helped by 2/3rds but still that's a lot of overshoot.  First is a 15V turn-on.  Second is the overshoot when a 15 ohm load gets disconnected.  7V overshoot is not great.  Next is 5V with 0.7A being disconnected, which should not be very taxing but is.  Finally I thought maybe it just needed a continuous load to dump some power into, so the last shot is the same as the second but with 10% continuous load added.  Still a pretty tall and long overshoot.

The overshoot isn't so bad with small current steps, but that's hardly a compliment.  I hope they get the regulation under control because this wouldn't be so bad if it weren't for this.  It's fine for battery charging but little else.  I intended it for a handy portable 24V supply for testing industrial devices but I don't think it'll even be suitable for that.  It produces the same spike when going from CC to CV so if you say accidentally short the leads, the device is going to get hit with a ~36V spike.