MAX1304–MAX1306/MAX1308–MAX1310/MAX1312–MAX1314
8-/4-/2-Channel, 12-Bit, Simultaneous-Sampling ADCs
with ±10V, ±5V, and 0 to +5V Analog Input Ranges
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Bipolar ±10V Devices
Table 7 and Figure 14 show the two’s complement trans-
fer function for the ±10V input range MAX1312/
MAX1313/MAX1314. The FSR is eight times the voltage at
REF. The internal +2.5V reference gives a +20V FSR,
while an external +2V to +3V reference allows an FSR of
+16V to +24V, respectively. Calculate the LSB size using:
which equals 4.88mV with a +2.5V reference.
The input range is centered about V
MSV
. Normally,
MSV = AGND, and the input is symmetrical about zero.
For a custom midscale voltage, drive MSV with an
external voltage source. Noise present on MSV directly
couples into the ADC result. Use a precision, low-drift
voltage reference with adequate bypassing to prevent
MSV from degrading ADC performance. For maximum
FSR, do not violate the absolute maximum voltage rat-
ings of the analog inputs when choosing MSV.
Determine the input voltage as a function of V
REF
,
V
MSV
, and the output code in decimal using:
V
CH_
= LSB x CODE
10
+ V
MSV