20
Chapter 4
Specifications
All specifications are subject to change without notice.
Typical for 25°C unless otherwise specified.
Specifications in italic text are guaranteed by design.
Analog input
Table 1. Analog input specifications
Parameter
Conditions
Specification
A/D converter type
Successive approximation type
Input voltage range for linear operation,
single-ended mode
CHx to GND
±10 volts (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
±28 V max
Input impedance
122 k
Ω
Input current (Note 1)
Vin = +10 V
70 µA typ
Vin = 0 V
–12 µA typ
Vin = –10 V
–94 µA typ
Number of channels
Software-selectable
8 single-ended / 4 differential
Input ranges, single-ended mode
±10 V,
G=2
Input ranges, differential mode
Software-selectable
±20 V,
G=1
±10 V,
G=2
±5 V,
G=4
±4 V,
G=5
±2.5 V, G=8
±2.0 V, G=10
±1.25 V, G=16
±1.0 V, G=20
Throughput (Note 2)
Software paced
250 S/s typ, PC-dependent
Hardware paced
50 kS/s
Channel gain queue
Up to 16 elements
Software configurable channel, range, and gain.
Resolution (Note 3)
Differential
12 bits, no missing codes
Single-ended
11 bits
CAL accuracy
CAL = 2.5 V
±36.25 mV max
Integral linearity error
±1 LSB typ
Differential linearity error
±0.5 LSB typ
Repeatability
±1 LSB typ
CAL current
Source
5 mA max
Sink
20 µA min, 100 µA typ
Trigger source
Software-selectable
External digital: TRIG_IN
Pacer source
Software-selectable
Internal
External (SYNC), rising edge triggered
Programmed IO
Note 1:
Input current is a function of applied voltage on the analog input channels. For a given input
voltage, V
in
, the input leakage is approximately equal to (8.181*V
in
– 12) µA.
Note 2:
Maximum throughput scanning to PC memory is machine dependent.
Note 3:
The AD7870 converter only returns 11-bits (0 to 2047 codes) in single-ended mode.