DM42: The internal view (hardware components)

[jordsan]

I have been able to further identify the following components:

Integrated Circuits:

• IC4: SiP32431 Ultra Low Leakage and Quiescent Current, Load Switch with Reverse Blocking. It is not an audio driver. The buzzer is connected directly to pin 64 and 65 of the micro; driven directly by it (it is a buzzer not a speaker after all). IC4 is connected to both the micro VDD and the battery.
• IC5: TPS61222DCK 5V Output, Low Input Voltage Boost Converter With 5.5μA Quiescent Current
  

Active Components:

• D1, D2: Diodes, marking AP, SOD-323 (SC-90) package, so far unable to cross reference the part number (D1 should be a TVS, D2 should be a schottky, and both should have ultra low reverse leakage current, but at least on my DM42 they are the same part).
• Q2: MMBT3904L NPN Transistor, general purpose.
  

Has anybody measured Vbat (pin 6 of the micro, or one side of C5) when on and then when off? The spec for the micro calls for 1.55V < Vbat < 3.6. My DM42 measures 0.7V at Vbat all the time!