ADS1291IRSMT datasheet(22/83 Pages) TI2

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CM+1/2V

REF

+1/2V

REF

1/2

Single-EndedInputs

INP

CMVoltage

REF

1/2

CM+1/2V

REF

DifferentialInputs

INP

INN

CMVoltage

1/2V

REF

-VREF

Common-ModeVoltage(DifferentialMode)=

(INP)+(INN)

,Common-ModeVoltage(Single-EndedMode)= INN.

INN=CMVoltage

InputRange(DifferentialMode)=(AINP

AINN)=2V

REF

Device

+1/2 V

1/2

REF

Common

Voltage

Single-Ended Input

Device

Peak-to-Peak

REF

Peak-to-Peak

REF

Common

Voltage

Differential Input

ADS1291, ADS1292, ADS1292R

SBAS502C – DECEMBER 2011 – REVISED APRIL 2020

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Product Folder Links: ADS1291 ADS1292 ADS1292R

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Feature Description (continued)

8.3.3 Analog Input

The ADS1291, ADS1292, and ADS1292R analog input is fully differential. Assuming PGA = 1, the differential

input (INP – INN) can span between –VREF to +VREF. Note that the absolute range for INP and INN must be

between AVSS – 0.3 V and AVDD + 0.3 V. Refer to Table 10 for an explanation of the correlation between the

analog input and the digital codes. There are two general methods of driving the ADS1291, ADS1292, and

ADS1292R analog input: single-ended or differential, as shown in Figure 20 and Figure 21. Note that INP and

INN are 180°C out-of-phase in the differential input method. When the input is single-ended, the INN input is held

at the common-mode voltage, preferably at mid-supply. The INP input swings around the same common voltage

and the peak-to-peak amplitude is (common-mode + 1/2 VREF) and (common-mode – 1/2 VREF). When the input

is differential, the common-mode is given by (INP + INN) / 2. Both INP and INN inputs swing from (common-

mode + 1/2 VREF to common-mode – 1/2 VREF). For optimal performance, it is recommended that the ADS1291,

ADS1292, and ADS1292R be used in a differential configuration.

Figure 20. Methods of Driving the ADS1291, ADS1292, and ADS1292R: Single-Ended or Differential

Figure 21. Using the ADS1291, ADS1292, and ADS1292R in Single-Ended and Differential Input Modes

ADS1291IRSMT Datasheet(PDF) 22 Page - Texas Instruments

ADS1291IRSMT Datasheet(HTML) 22 Page - Texas Instruments

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