Chapter 4
Specifications
Typical for 25°C unless otherwise specified.
Specifications in italic text are guaranteed by design.
Analog input
Parameter Conditions Specification
A/D converter type Successive approximation type
Input voltage range for linear operation,
single-ended mode
CHx to GND ±10 V max
Input common-mode voltage range for
linear operation, differential mode
CHx to GND -10 V min, +20 V max
Absolute maximum input voltage CHx to GND ±40V max
Vin = +10 V 70µA typ
Vin = 0V -12µA typ
Input current (Note 1)
Vin = -10 V -94µA typ
Input impedance 122K Ohms
Number of channels
8 single ended / 4 differential, software
selectable
Input ranges, single-ended mode ±10V, G=2
Input ranges, differential mode ±20V, G=1
±10V, G=2
±5V, G=4
±4V, G=5
±2.5V, G=8
±2.0V, G=10
±1.25V, G=16
±1.0V, G=20
Software selectable
Software paced 50 S/s
Continuous scan 1.2 kS/s
Throughput
Burst scan to 4 K
sample FIFO
8 kS/s
Channel gain queue Up to 8 elements Software configurable channel, range, and gain.
Differential 12 bits, no missing codes Resolution (Note 2)
Single ended 11 bits
CAL accuracy CAL = 2.5V ±0.05% typ, ±0.25% max
Integral linearity error ±1 LSB typ
Differential linearity error ±0.5 LSB typ
Repeatability ±1 LSB typ
Source 5 mA max CAL current
Sink 20 µA min, 200 nA typ
Trigger Source Software selectable External digital: TRIG_IN
Note 1:
Note 2:
Input current is a function of applied voltage on the analog input channels. For a given input
voltage, Vin, the input leakage is approximately equal to (8.181*Vin-12) µA.
The AD7870 converter only returns 11-bits (0-2047 codes) in single-ended mode.
4-1
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