Microsoft Wireless Mouse Power Circuitry

 The Microsoft wireless mouse takes two AA batteries in parallel.  Tests show that it can start at 0.8V and run down to 0.7V provided that there is enough current, which is generally not available when the batteries are drained to this low.   The voltage has to be boosted to run the optical mouse sensor, the LED and the EEPROM.  There is a boost converter, a 10-pin SSOP IC U2 that I could not identify.   But I believe it is a synchronous boost converter.   The output of the converter is measured to be 1.8V.    

We also see two diodes (D1 and D2) and another voltage of 3.2V.   We  can see the following circuit.

We can see the switch node S (Ch1) and the node A (Ch4).

The switching frequency is about 550KHz.  When the switch is on driving the node S to ground, the node A is being charged up to 1.8V and when the switch is turned off, the node S is up to about 1.8V and the output diode is turned on to drive the node B to 3.2V.   This appears to be common technique to generate an auxiliary voltage.