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ADS7955 / Vdd under the 2*Vref

Ryuji
Guru 20090 points

Other Parts Discussed in Thread: ADS7955

Hello,
 
Please let me know the behavior of ADS7955.
 
Vref is set to Range 2 then VA falling to under the 2*Vref.
In this case, Input range(max) becomes the VA.
There is not other problem.
Is my understanding correct ?
 
For example ,
VA is 5V and Vref is set Range 2(2*Vref).
In this stage , input voltage range is 0V to 5V.
After this, the VA fell to 4.0V.
Thus, the input voltage range becomes 0V to 4V.
 
Best Regards,
Ryuji Asaka
 
  • 0
    TI__Expert 4405 points

    Ryuji-san,

    As per the ADS7955 datasheet, we spec the input range max as 2Vref with the condition that 2Vref <= VA.

    The device can be used as you have described, with the input range restricted to VA+=4V. However, please note that you will not be able to get the full dynamic range of the device and the codes corresponding to the voltages between VA and 2Vref (in this case, 4V to 5V) would not be available.

    NOTE: Care should always be taken that inputs should not exceed VA (=4V) else the ESD diode would turn on and distort the input signal.

    Regards,

    Sandeep

  • 0 in reply to Sandeep Kasargod
    Guru 20090 points
    Hello,
     
    Thank you for the reply.
    I understood.
     
    Best Regards,
    Ryuji Asaka