• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 1161 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.

TMS320F28377S: a 28377S ADC questione

Shuai Peng
Intellectual 780 points
Part Number: TMS320F28377S

My customer use the 28377S do the Inverter,they found that not all the channel of the ADC have the same performance. For example ,they use two channel to measure the same signal,and the results vary widely.and on the datasheet I found that the Cp of each channel vary widely.Could this be a reason?Why do we design like this? and do we have some suggestions for our customer ？And now ,my customer use the abnormal channel acquire the temperture signal,use the normal channel do the current sampling.

  • 0
    TI__Guru 60865 points
    Hi Shuai,

    The differences in capacitance are due to internal routing differences among the ADC channels. This is probably not significantly affecting the ADC results unless the S+H duration is much much too short (with the exception of the VDAC/B0 pin, where settling could be slowed due to the significantly increased capacitance).

    More likely, the issue is that there is a parasitic ~50k pull-down on the pins muxed with the buffered DAC. This parasitic pull-down is present even when the DAC is disabled on this device. This can adversely affect the ADC conversion results if the input driver is not very strong.
  • 0 in reply to Devin Cottier
    TI__Intellectual 780 points
    Hi Devin,
    Excuse me ，For this problem，I have send a mail to you, can you help do some analysis ? Very appreciated! Thank you.