I applied external reference of 3V.
Can I measure 3.3V by ADC or I will get Maximum ADC count.
Please suggest a method to measure 3.3V without using any other component like resistance divider or attenuator.
Applied Vcc to Micro is 3.3V.
Thanks in Advance
Generally, it depends on the Analog Reference Voltage applied to the chip. Looking at a random STM32 datasheet seems to suggest that:
Depending on what Vdda you apply (this could be hooked to Vcc but not necessarily), the range of your ADC changes. Vdda can range from 1.7 to 3.6V. If you apply Vcc to Vdda, then you will get (ideally) maximum ADC count for Vcc input.
Applying voltages greater than Vref+to the input is not recommended generally speaking, as this could result in current flow through protective internal diodes. If the current is limited, it may be tolerated, but the unit will probably saturate either at maximum ADC count (or some can exhibit undefined behaviour). Best to go with a divider in this case - otherwise just tie Vdda to Vcc through an appropriate smoothing filter.
- Gough
Generally, it depends on the Analog Reference Voltage applied to the chip. Looking at a random STM32 datasheet seems to suggest that:
Depending on what Vdda you apply (this could be hooked to Vcc but not necessarily), the range of your ADC changes. Vdda can range from 1.7 to 3.6V. If you apply Vcc to Vdda, then you will get (ideally) maximum ADC count for Vcc input.
Applying voltages greater than Vref+to the input is not recommended generally speaking, as this could result in current flow through protective internal diodes. If the current is limited, it may be tolerated, but the unit will probably saturate either at maximum ADC count (or some can exhibit undefined behaviour). Best to go with a divider in this case - otherwise just tie Vdda to Vcc through an appropriate smoothing filter.
- Gough
