System information

Analog Input
VSBC-6 Reference Manual Reference – 45
T
WO
'
S
C
OMPLEMENT
D
ATA
F
ORMAT
(±5V
AND
±10V O
NLY
)
The A/D converter translates applied analog voltages into 12-bit, two’s complement digital
words. The full analog input range is divided into 4096 steps. The output code (0000h) is
associated with a mid-range analog value of 0 Volts (ground).
The formulas for calculating analog or digital values are given by:
Digital =
Analog
Step
Analog = Step Digital
x
Where:
Analog = Applied voltage
Digital = A/D Conversion Data
Step = 0.004882813 Volts (0 to +10V Range)
0.002441406 Volts (0 to +5V Range)
Sample values are shown in the table below:
Table 22: Two's Complement Data Format
±5V Input
Voltage
±10V Input
Voltage Hex Decimal Comment
+5.000000 +10.000000 — — Out of range
+4.997559 +9.995117 07FFh 2047 Maximum positive voltage
+2.500000 +5.000000 0400h 1024 Positive half scale
+1.250000 +2.500000 0200h 512 Positive quarter scale
+0.002441 +0.004883 0001h 1 Positive 1 LSB
0.000000 0.000000 0000h 0 Zero (ground input)
–0.002441 –0.004883 FFFFh –1 Negative 1 LSB
–1.250000 –2.500000 FE00h –512 Negative quarter scale
–2.500000 –5.000000 FC00h –1024 Negative half scale
–5.000000 –10.000000 F800h –2048 Maximum negative voltage