We have found a strange issue with the MC34708:
Note: In our system OTG is always client.
- If we have nothing connected to the USB OTG port we can reset the device by pressing the power button (PWNON1) for >4 seconds (that's how we configured the MC34708).
- If we have a cable connected from the USB OTG port to a host port on a PC, we CAN NOT reset the device by pressing the power button (PWNON1) for >4 seconds.
The reset button (GLBRST) still works as expected, in both cases.
After power on reset, we set the MC34708 like this:
SW1AMODE = 0x0C
SW2MODE = 0x0C
SW3MODE = 0x0
SW4AMODE = 0x0C
SW4BMODE = 0x0C
SW5MODE = 0x0C
SWBSTMODE = 0x02 (but also tried 0x00, no difference)
SW1 VOLT = 1100 mV
SW1 STDBY = 850 mV
SW2 VOLT = 1300 mV
SW2 STDBY = 950 mV
Regulator Mode 0
VUSBSEL = 0x01
SWHOLD = 0x0 (but also tried 0x01, no difference)
Power Control 2:
RESTARTEN = 1
PWRON1RSTEN = 1
STANDBYINV = 1
GLBRSTTMR = 1
WDIRESET = 1
The above settings are done in the bootloader, after that, the PMIC is not touched anymore.
OS = WEC7 (but for this question the OS shouldn't matter)
Anybody any idea what could cause this behavior and how to fix it?