SIM922A/923A Temperature Monitors0 pages

Small Instrumentation Modules
SIM922A and SIM923A — Diode and Pt RTD temperature monitors with analog outputs

· Single-channel LED display
· 1.4 K to 475 K with Si, GaAs or
GaAlAs diodes
· 20 K to 873 K with platinum RTDs
· Two analog outputs:
t
Linearized V proportional to T
t
Sensor voltage (buffered)

· SIM922A ... $895 (U.S. list)
· SIM923A ... $895 (U.S. list)

SIM922A and SIM923A Temperature Monitors
The SIM922A Diode Monitor and the SIM923A RTD Monitor
continuously read a single sensor and provide both digital and
analog outputs. Based on the modular SIM platform, they
provide high performance capability in a small footprint.
SIM922A
The SIM922A has a programmable, precision 10 µA current
source to provide sensor excitation. Results can be displayed
in either kelvins or volts.
SIM923A
The SIM923A has selectable 10 µA and 1 mA current sources
to provide sensor excitation. Sensor resistance is determined
ratiometrically with a half-bridge circuit consisting of the
sensor and an internal reference resistor. The current to the
sensor can be reversed by the user to test for any offset.
Measurement results can be displayed in either kelvins
or ohms.

Stanford Research Systems

Common Features
Both the SIM922A and SIM923A employ four-wire
measurement circuits (±I excitation leads, ±V sense leads),
making readings insensitive to series lead resistance. Sensor
excitations can be disabled to reduce power dissipation at
sensitive cryogenic stages. Measurements are performed at
five readings per second.
The scaled analog output (±10 V) produces a voltage
proportional to measured temperature, with a full-scale range
from 10 K to 1000 K. A relative-mode button subtracts the
last absolute reading prior to scaling to provide expanded
resolution for temperature deviations. The second (monitor)
output is the buffered, low-noise raw sensor voltage without
any additional processing.
Either analog output may be coupled to the SIM960 Analog
PID Controller for closed-loop temperature control.

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