• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 48 subscribers
  • Views 153 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

LMH32401: LMH32401

Giora Eytan
Expert 1235 points
Part Number: LMH32401
Other Parts Discussed in Thread: ADC12QJ1600

an you explain this parameters from the data sheet:

In simulation I am getting maximum VOH ~ 2V not 2.9V.

Sincerely,

Giora

  • 0
    TI__Genius 9850 points

    Hi Giora,

    The limiting factor is likely due to the VOCM voltage. The device is trying to not only gain the signal but also adjust the outputs to be equal to VOCM. This is why in theory the outputs should be higher due to the input signal gained up, but it is limited by the VOCM circuitry. You can adjust VOCM higher and it will bias the outputs which should result in a higher output voltage.

    Best Regards,

    Ignacio

  • 0 in reply to Ignacio Vazquez Lam1
    Expert 1235 points

    Hello,

    Thanks.

    currently we are designing an interface to an ADC with max SE analog input for the _P and _N side of 2.1V.

    The LMH32401 datasheet states the maximum voltage on the _P or _N outputs of 2.9V - this value can cause damage to the ADC analog input stage. 

    In the simulation with VDD=3.3V VCOM=OPEN VOD=0V we cannot reach more than the ~2V, even with 100mA pulse current. 

    We need to understand if to add protection circuitry on the ADC input? ( Our ADC is ADC12qj1600 )

    Can you  help here? 

    Do you have any recommendations/application note which address this issue? 

    Thanks 

    Giora

  • +1 in reply to Giora Eytan
    TI__Genius 9850 points

    Hi Giora, 

    The output voltages at each output depend on Vocm, therefore the only way to get the absolute voltage to increase is by adjusting the Vocm. At 0V, the outputs will be limited. Adjusting the Vocm voltage to a higher value will increase the output swing of the device. As for your other question, it would be best to create a separate thread with the ADC team to provide options for protecting the ADC. Some ADCs have internal circuitry to protect the ADC while others do not.  They would be the best option for providing appropriate collateral on this topic.

    Best Regards,

    Ignacio