I am troubleshooting three CPU module which failed to bootup due to the VSNVS output voltage is <3.0 V. Three units have different VSNVS: 2.0 V, 1.8 V, 1.63 V. I have tried to replace a new component on one board but the output voltage of VSNVS is still 1.8V. The supplied voltage to VIN is 3.3V.
I understand that the PMIC when powered by VIN, VSNVS is an LDO capable of supplying seven voltages: 3.0, 1.8, 1.5, 1.3, 1.2, 1.1, and 1.0 V. The bits VSNVSVOLT[2:0] in register VSNVS_CONTROL determine the output voltage and the default setting of the VSNVSVOLT[2:0] is 110, or 3.0 V, unless programmed otherwise in OTP.
I used PMIC (MMPF0100F2AEP) with imx6 dual lite SoC (MCIMX6U5DVM10AC) in my CPU module. The PMIC is pre-programmed (F2 configuration) and I don't use coin cell, just a 0.1uF capacitor connected to LICELL.
Any input on why the VSNVS voltage is < 3.0 V although VIN supplied to PMIC is 3.3 V?