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MSP430I2040: SD24 input range

Lisa Ding
Expert 6525 points
Part Number: MSP430I2040

Hi Champs,

According to datasheet table5-2, it showed VID input range is +-928mv when SD24GAINx = 1 for specified performance. However, SD24 reference volt is 1.158v for internal reference volt. In theoretically , input range should be -VREF/GAIN=-1.158 ~ VREF/GAIN=1.158. Could you please tell me can we input voltage between 0.928v and 1.158v ? 

If input voltage is limited within +-928mv. Is LSB = 0.928/2^24 =  110nv ?

thanks for your reply in advance.  

  • 0
    TI__Guru**** 212687 points
    Hi Lisa,

    You may not have noticed footnote 2 of Table 5-21 which states that the differential input voltage range for specified performance (Table 5-22) is 80% of VFSR+, therefore 1.158 V * 0.8 = 928 mV. This limitation is due to the amplifier (PGA) built in to the SD24 and performance may degrade (go outside of specs) when the input voltage is this close to the rails. The LSB is still 1.158/2^24 = 69 nV.

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    TI__Expert 6525 points

    Hi Ryan,

    Thanks for your reply. I know the reason now. thank you.

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