I have the following situation:
- STM32L471/L476 processor
- Using the ADC with the internal reference buffer (2.5V) as analog eference
- One of the ADC input signals comes from a rail-to-rail OP-AMP with 3V supply voltage, so this input signal can be up to 3V, and therefore higher than the ADC reference voltage
- Normally this ADC input signal will be within 0 to 2.5V but it might occassionally exceed that range and then go up to 3V
Now my question is:
Is it a problem when the ADC input voltage is above the reference voltage? I know that some ADC's can get damaged in this case. In the datasheet I found that
- GPIO VIN max = 4V (STM32L476xx Datasheet, DocID025976 Rev 3, Table 18)
- This absolute maximum rating I would fulfill
- ADC VAIN Conversion voltage range max = VREF+ (STM32L476xx Datasheet, DocID025976 Rev 3, Table 62)
- This looks like it is just where the ADC converts but not like a do-not-exceed limit
So if the ADC in this configuration can get damaged by a 3V voltage I would look for some alternative (other reference, limit input signal externally) but it would be the best if it could withstand it.
- I cannot use the 3V supply of the OP-AMPs as it is switched on/off but I need a constant analog refernce since I require the DACs all the time
- Using another 3V supply would be possible but costly (this is a device prototype)
Hope you could undestand my problem, otherwise just let me know.
Thanks in advance and kind regards