Repairing Emporia Vue Gen 2 energy monitor.Help finding what pmic chip this is.

[Fflint]

I'm trying to repair an energy monitor. An Emporia Vue gen 2 that was hooked up with neutral and phase 3 reversed. Two MOVs blew up and this Pmic in a soic8 case.

Unfortunately the markings turn nothing in Google. Looking through the microscope it looks like the first letter is P but other photos of the product show same chip with other marking starting with 8.

Here is the broken one:


And here is another photo from the web:


It seems pins 5 to 8 are connected together to the transformer and through a diode and resistor to another pin on the transformer (same winding?) Marking on my chip is:
PGFDSA or BGFDSA
The one in another picture has marking:
BGFCN8

Can anyone help?

 That is all the clue I have :-(

[Fflint]

There is also this internal structure from a reverse engineered schematic:



If anyone knows an equivalent ic that would be great. Even if the pinout is different I could bodge-wire it.

[Fflint]

After hooking it up to 5V on the logic side it connects to WiFi, logs into its cloud account and makes all the right sounds and noises. But measurements through CTs all come as zeros.

I checked all voltages are present, but I can't figure out how to test if the right measurement signal is present.

Here is the schematic of where the CT is plugged in:


It is connected to what looks like an analog multiplexer and into a Mcu with an ADC. However despite varying the current the CT is supposed to measure I get 1.8V on output. Nothing else. (viewed with an oscilloscope).

The CT has very low resistance of 19ohm so trying to use it with the usual burden resistor of few hundred ohms doesn't work. I tried with 20 ohm, but I thing all i saw was 50hz buzz getting picked up.

Is anyone here familiar with such measurement circuits?

[fzabkar]

You might have better luck finding it if you were to search for "flyback converter" or "flyback regulator".

Also, your U1 pinouts don't seem to be correct. Pin #1 looks like Vcc, and pin #4 looks like current sense, and pin #2 seems to be ground.

[fmashockie]

I agree with Fzabkar.  The reverse engineered schematic you have clearly isn't drawn correctly.  I would try tracing it out yourself because this is just going to throw you off.

I would also try searching for SOIC-8 AC/DC converters on Mouser/Digikey once you have the schematic drawn out correctly.  The more you can do, the better.  It clearly has a built in MOSFET.  Maybe pin 1 is an internal Bypass pin or Vcc. 

Good luck!