Datasheet
2001
1FFF
0000
Positive
FSR 1LSB-
0V
Negative
FSR+1LSB
DifferentialAnalogInput(AINxP AINxN)-
ADCCode(Hex)
3FFF
-1LSB
V
IN
ADS7945
ADS7946
www.ti.com
SBAS539B –JUNE 2011– REVISED SEPTEMBER 2011
ADC TRANSFER FUNCTION
The ADS7945 is a differential input device and the ADS7946 is a single-ended input device. This section
describes the transfer characteristics for both devices.
The ADS7945 output is in twos compliment format. Figure 79 shows the ideal transfer characteristics for these
devices. Here, full-scale range for the ADC input (AINxP – AINxN) is equal to twice the reference input voltage to
the ADC 2 × (V
REF
). 1 LSB is equal to 2 × (V
REF
/2
N
), where N is the resolution of the ADC (N = 14 for the
ADS7945). The differential input of the ADC is bipolar around the common-mode voltage (AINxP + AINxN)/2 and
has a range of positive FSR (+V
REF
) to negative FSR (–V
REF
).
Figure 79. ADS7945 Transfer Characteristics
Copyright © 2011, Texas Instruments Incorporated Submit Documentation Feedback 27
Product Folder Link(s): ADS7945 ADS7946