STM32F446RE DAC External Protection

[Paddy611]

Hi,

Greetings!!

We have implemented internal DAC (DAC1 and DAC2 both) in STM32F446RE chip. Both the DAC gives identical analog voltage from the range of 0-1V corresponding to the measurement reading of 0-100. 

This analog output voltage is connected to the data logger through DAC1, whereas the DAC2 is not connected anywhere. 

During the testing (After 5 days after the device is powered on and kept under observation) it has been observed that the DAC1 output stopped working. When compared with the DAC2 output (which is not connected to data logger or any other system) is working as expected. 

This has happened multiple times on multiple devices. Any suggestion why this is happening and what precautions are required while handling the DAC signal. 

No protection circuit is implemented at the DAC output. DAC output is directly connected to the data logger and other interconnection system( another MCU which is reading this DAC voltage)

Kindly share the views. 

Attached the image of the data log. The 5 units are implemented and kept under observation. Out of that in 2 units DAC stopped working (marked in the green circle)

[mƎALLEm]

Hello,

Are you sure the DAC1 is not disturbed externally by that "data logger"?

Are you sure the data logger impedance value is inline with the specification?:

If you disconnect the data logger are you seeing DAC1 getting back to a normal operation?

Try to add a voltage follower on DAC1 output to adapt the impedance.