Maxim Integrated MAXQ7667 - Manual (Page 245)

14-13 _________________________________________________________________________________________________________
MAXQ7667 User’s Guide
The MAXQ7667 ADC output is two’s complement in bipolar mode. Figure 14-5 shows the MAXQ7667 ADC bipolar transfer function.
Table 14-3 shows the bipolar relationship between the differential analog input voltage and the digital output code. In bipolar mode,
the inputs are measured in a truly differential fashion where either input can exceed the other by up to REF/2.
Figure 14-5. Bipolar Transfer Function
800
801
FFE
001
000
FFF
7FE
7FF
-FS 0 +FS
O
U
T
P
U
T
C
O
D
E
(h
e
x
)
DIFFERENTIAL INPUT VOLTAGE (LSB)
+FS - 1.5 LSB
FULL-SCALE
TRANSITION
+FS = REF/2
ZS = 0
-FS + 0.5 LSB
-FS = -REF/2
1 LSB = REF/4096
Table 14-3. Bipolar Code Table
BINARY DIGITAL
OUTPUT CODE
D11–D0
HEXADECIMAL
EQUIVALENT OF
D11–D0
DECIMAL
EQUIVALENT OF
D11–D0 (CODE 12 )
DIFFERENTIAL INPUT
VOLTAGE (V)
(EXTERNAL, REF = 2.5V)
0111 1111 1111 0x7FF +2047 +1.24939 ± 0.5 LSB
0111 1111 1110 0x7FE +2046 +1.248779 ± 0.5 LSB
0000 0000 0001 0x001 +1 +0.00061 ± 0.5 LSB
0000 0000 0000 0x000 0 0.000 ± 0.5 LSB
1111 1111 1111 0xFFF -1 -0.00061 ± 0.5 LSB
1000 0000 0001 0x801 -2047 -1.24939 ± 0.5 LSB
1000 0000 0000 0x800 -2048 -1.25 ± 0.5 LSB