Datasheet

+1/2 V
REF
V
REF
1/2
Single-Ended Inputs
t
INP
CM Voltage
Differential Inputs
t
INP
INN
CM Voltage
+V
REF
V
REF
Common-Mode Voltage (Differential Mode) =
(INP) + (INN)
2
, Common-Mode Voltage (Single-Ended Mode) = INN
INN = CM Voltage
CM + 1/2 V
REF
CM
1/2 V
REF
CM
1/2 V
REF
CM + 1/2 V
REF
Input Range (Differential Mode) = (AINP – AINN) = 2 V
REF
a) Single-Ended Input b) Differential Input
Device
Common
Voltage
1/2 V
REF
to
+1/2 V
REF
Device
V
Peak-to-Peak
REF
V
Peak-to-Peak
REF
Common
Voltage
ADS131E04
ADS131E06
ADS131E08
www.ti.com SBAS561A –JUNE 2012–REVISED APRIL 2013
ANALOG INPUT
The ADS131E0x analog input is fully differential. Assuming PGA = 1, the differential input (INP – INN) can span
between –V
REF
to +V
REF
. Refer to Table 5 for an explanation of the correlation between the analog input and
digital codes. There are two general methods of driving the ADS131E0x analog input: single-ended or
differential, as shown in Figure 19 and Figure 20, respectively. 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 V
REF
) and (common-mode – 1/2 V
REF
). 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 V
REF
to
common-mode – 1/2 V
REF
). For optimal performance, it is recommended that the ADS131E0x be used in a
differential configuration.
Figure 19. Methods of Driving the ADS131E0x: Single-Ended or Differential
Figure 20. Using the ADS131E0x in Single-Ended and Differential Input Modes
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