Reason for glitch at the Output of DAC when Analog supply to it is switched off ?

[vikasveshan]

Hi all ,

I am using a 16 bit R-2R ladder DAC for generating voltage output.
The analog supply to the DAC is ( Avdd/Avss ) +/- 15V and i have configured the DAC so as to get output of 10V .
When i switch off the analog supply to the DAC , the DAC output starts decreasing as expected till supply voltages reach about 6V/-9V ( Avdd/Avss) .
At AVdd/Avss = 6V/-9V i observe a glitch at the Vout ( The Vout shoots down to -8.9V for around 400uS and then again rises up to 0V.

I would be thankful if anyone could help me in understanding the reason behind the glitch.


Thanks & regards !!
VV

 

[keith1200rs]

It will be various parts of the IC stopping working at different voltages. If you want a glitch free turn off you will need to isolate the out - add an analogue switch for examples.

Keith