I am working with the XEM8320 EVB (REVISION C 05). During the power up of the EVB, U21, MYMGM1R816ELA5RA, should receive a logic high (‘1’) at the REMOTE ON/OFF pin in order to turn ON.
According to the scheme, the VCCINT_EN pin—which should drive this signal—does not appear to be connected to any connector or other enable signal. It seems to be pulled down by resistor R207, so it should default to logic low (‘0’).
If that’s the case, how is U21 (MYMGM1R816ELA5RA) turning ON?
Additionally, when I measured the voltage at this pin on the EVB, it was 3.3V. How is that possible if the schematic doesn’t show any connection driving it high?
Also, it deosn’t seems that PMBUS pins of U21 ( in the scheme AVR_I2C_3V3) are connected to anything.
Additionaly, is the output voltage of U21 configured in any way, or is Vout defined only by the output resistor (Rtrim – R133)?