Measurement Computing USB-TEMP-AI - Manual (Page 19)

19
Chapter 5
Specifications
All specifications are subject to change without notice.
Typical for 25 °C unless otherwise specified.
All specifications apply to all temperature and voltage input channels unless otherwise specified.
Specifications in italic text are guaranteed by design.
Analog input
Table 1. Generic analog input specifications
Parameter Conditions Specification
A/D converter type T0x to T3x, V0x toV3x AD42_321
Dual 24-bit Sigma-Delta
Number of channels Voltage input; V0x toV3x 4 differential, 4 single-ended
Temperature input; T0x toT3x 4 differential
Input isolation 500 VDC minimum between field wiring and USB
interface
Channel configuration T0x toT3x Temperature input.
Software programmable to match sensor type
V0x toV3x Voltage input
Analog input modes Power up and reset state Factory default configuration is Disabled mode.
Once configured, each channel reverts to the mode
previously set by the user.
Single-ended Vx_H inputs are connected directly to their screw
terminal pins.
Vx_L inputs are disconnected from their screw
terminal pins and internally connected to GND.
Differential Vx_H and Vx_L inputs are connected directly to
their screw terminal pins.
Tx_H and Tx_L inputs are connected directly to
their screw terminal pins.
Input ranges Thermocouple; T0x toT3x ±0.080 V
RTD; T0x toT3x 0 to 0.5 V
Thermistor; T0x toT3x 0 to 2 V
Semiconductor sensor; T0x toT3x 0 to 2.5 V
Voltage; V0x toV3x ±10 V, ±5 V, ±2.5 V, ±1.25 V; software selectable
Absolute maximum input
voltage T0x to T3x relative to GND
(pins 9, 19, 22, 27, 30, 33, 36, 39, 49) ±25 V max (power on)
±40 V max (power off)
V0x to V3x relative to GND
(pins 9, 19, 22, 27, 30, 33, 36, 39, 49) ±25 V max (power on)
±15 V max (power off)
Input impedance T0x to T3x 5 GΩ (power on)
1 MΩ (power off)
V0x to V3x 10 GΩ (power on)
2.49 kΩ (power off)
Input leakage current T0x to T3x, with open thermocouple
detect disabled. 30 nA max
T0x to T3x, with open thermocouple
detect enabled. 105 nA max
V0x to V3x ±1.5 nA typ, ±25 nA max
Input bandwidth (–3 dB) T0x to T3x 50 Hz
V0x to V3x 3 kHz