My customer using LM4132-1.8V.
VIN is ST MCU's GPIO(SENSING_VDD_CTRL) and this GPIO current spec is below and total current consumption is about 180uA.
VREF is for ST MCU's ADC reference.
1) No Yellow Resistor, Disable ADC : VREF voltage is 1.8V, OK
2) No Yellow Resistor, Enable ADC : VREF voltage is about 2.4V, it is not correct.
3) Yellow Resistor (670 ~ 6.2KOhm), Enable ADC ; VREF voltage is 1.8V, OK.
Why this situation is occurred?
Why VREF is not correct in 2) case?
Why VREF is correct in 3) case?
Please let me know.