# Understanding ADC input voltage range from its specifications

I want to use this ADC, an LTC2344-18, a quad, 18-Bit, 400ksps ADC. On page 15 you can see that the analog voltage input range can be set to +-Vrefbuf. Vrefbuf can be set to 2.5V to 5V. This would mean the analog inputs could accept a voltage between -5V and +5V.

However on page 2, in the absolute maximum ratings section, it is stated that the analog voltage input range is from -0.3V to Vdd+0.3V.

Does it mean that the -5V to +5V range is maybe between a common mode voltage of let's say +5V? So it would mean that the full scale range will be between 0V and 10V?

• See typical application, page 1, bottom picture. Do you see ... inputs which are noted "fully" differential ... but voltages must be for each inputs within +5V/0V ... Commented Sep 14, 2021 at 13:34

This would mean the analog inputs could accept a voltage between -5V and +5V.

No.

it is stated that the analog voltaghe input range is from -0.3V to Vdd+0.3V.

Let's say that the input range is 0..Vdd, positive only, so it can't accept negative voltage at the inputs.

Does it mean that the -5V to +5V range is maybe between a common mode voltage of lets say +5V?

It's a differential voltage $$V=V_+-V_-$$ $$\V_+=5V; V_-=0\rightarrow V=5V \$$

$$\V_+=0V; V_-=5\rightarrow V=-5V \$$

It would make sense to use a common mode voltage of 1/2 input voltage range, for example 2.5V.