Negative and positive voltages with LTC1403


Im new here and also electronics ;). I need to measure +/- 3.3V signal. I usually use microcontollers with level shifter but now I need some more precise ADC. I picked LTC1403. How can I measure negative voltages with differential input? Do I need level shifter and IN connect to ground? Or to minus of my of my power supply? Its my first time with external ADC.

Before signal I have some filters.

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    •  Analog Employees 
    on May 29, 2019 3:25 PM over 1 year ago in reply to Kil307

    The inputs of the LTC1403 will have a small transient on them when the ADC goes into acquire mode. This transient must settle before the start of the conversion. This is the acquisition time of the ADC. For the LTC1403 running at its full speed the acquisition time is only 39ns. If you look at the small signal step response of the LTC1992 you will see that it takes over a 1us to settle. If you look at the settling time of the ADA4945 in low power mode, it settles to a 16-bit level in 150ns. This is to an 8V step. Settling to 12bits from the small transient on the ADC inputs should be possible in 39ns. The supply current of the ADA4945 in low power mode is not that much more than the LTC1992.