• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 214 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

What happens when DDC264 integration time too long?

Ron Ying
Intellectual 285 points
Other Parts Discussed in Thread: DDC264

Dear Sir/Madam,

I have a question regarding DDC264 power up sequencing: in the DDC264 spec (SBAS368C –MAY 2006–REVISED JULY 2011) Figure 33 Page 20, after "Strobe CONV", it becomes normal operation. At that time CONV is low:

1) at that time (CONV at low), have all the integrators started integration at the falling edge of the CONV?

2) If the integration time is too long, any damage or harm to the DDC264?Will the integration capacitor be reversely charged? will the AD (measurement) report a full scale number in that case or will report a random number?

Thanks,

Ron

  • 0
    TI__Expert 4680 points

    Hi Ron,

    Integrating for too long will saturate (report full scale number) the output and this can lead to loss of -ve feedback and this, in turn, will allow the input node to swing. Eventually, the node may reach the ESD turn on levels, but we do not anticipate damage as long as the currents are small. One additional potential effect is that if the input losses virtual gnd and if the esd turns on then it is possible that adjacent channels which are not overloaded can also see leakage currents which can cause incorrect outputs on adjacent channels as well.

    For your other question, I think that when CONV goes low, side B starts to be integrated. The side A was not integrated correctly. So, the data that you get on the first DVALID after the CONV edge went down should not be correct (as it is the data from A). But this is just my thinking. I asked the design team to let me know... and will post as soon as I find out.

    Best regards,
    Edu