MP2672A high standby power consumption

[richardantalik]

I have fairly simple design for a small torch, but I am having trouble getting low standby current. Right now I can measure about 35mA. So far everything points to MP2672A chip. I see the current on the shunt resistor confirmed with multimeter. There is no difference in current if I set EN_SUSP to 0. Vbus is 0V during measurement.

I don’t quite see the problem in my setup, so I thought I will ask here. Technically I could desolder the shunt to double check if this chip is the real issue, but I would like to avoid doing that (it’s assembled and it’s quite complicated to disassemble the thing).

Here is register dump:

> mpread 0
Reg 0x00: 0x28
> mpread 1
Reg 0x01: 0x8F
> mpread 2
Reg 0x02: 0x85
> mpread 3
Reg 0x03: 0x00
> mpread 4
Reg 0x04: 0x00

And schematic:

Thanks for all advice!

[richardantalik]

So I’ve had opportunity to dig into this device, and mea culpa, the 30mA power draw was coming from SAMD21 chip (you need PhD to put it to sleep apparently). The fact that the value was seen on shunt was just coincidence In the end a cheap thermal camera did show this, so I did not even have to desolder stuff.