SCM5B37
Thermocouple Input Modules
FEATURES
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INTERFACES TO TYPES J, K, T, E, R, S, C, N AND B
THERMOCOUPLES
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HIGH LEVEL VOLTAGE OUTPUTS
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1500Vrms TRANSFORMER ISOLATION
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ANSI/IEEE C37.90.1-1989 TRANSIENT PROTECTION
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INPUT PROTECTED TO 240VAC CONTINUOUS
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160dB CMR
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95dB NMR AT 60Hz, 90dB at 50Hz
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±0.05%
ACCURACY
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±0.02%
LINEARITY
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±1µV/°C
DRIFT
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CSA CERTIFIED, FM APPROVED, CE COMPLIANT
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MIX AND MATCH SCM5B TYPES ON BACKPANEL
The SCM5B modules are designed with a completely isolated computer
side circuit which can be floated to
±50V
from Power Common, pin 16. This
complete isolation means that no connection is required between I/O
Common and Power Common for proper operation of the output switch. If
desired, the output switch can be turned on continuously by simply
connecting pin 22, the Read-Enable pin to I/O Common, pin 19.
The SCM5B37 can interface to nine industry standard thermocouple types:
J, K, T, E, R, S, C, N, and B. Its corresponding output signal operates over
a 0V to +5V range. Each module is cold-junction compensated to correct
for parasitic thermocouples formed by the thermocouple wire and screw
terminals on the mounting backpanel. Upscale open thermocouple detect
is provided by an internal pull-up resistor. Downscale indication can be
implemented by installing an external 47MΩ resistor,
±20%
tolerance,
between screw terminals 1 and 3 on the SCMPB01/02/03/04/05/06
backpanels.
Signal filtering is accomplished with a six-pole filter which provides 95dB
of normal-mode-rejection at 60Hz and 90dB at 50Hz. Two poles of this filter
are on the field side of the isolation barrier, and the other four are on the
computer side.
After the initial field-side filtering, the input signal is chopped by a
proprietary chopper circuit. Isolation is provided by transformer coupling,
again using a proprietary technique to suppress transmission of common
mode spikes or surges. The module is powered from +5VDC,
±5%.
A special input circuit on the SCM5B37 modules provides protection
against accidental connection of power-line voltages up to 240VAC.
For Class I, Division 2 hazardous location applications, refer to Dataforth
installation manual MA1146 (available upon request).
DESCRIPTION
Each SCM5B37 thermocouple input module provides a single channel of
thermocouple input which is filtered, isolated, amplified, and converted to
a high level analog voltage output (Figure 1). This voltage output is logic-
switch controlled, allowing these modules to share a common analog bus
without the requirement of external multiplexers.
+2.5V
100MΩ
4
NC
4
+In
Thermocouple
–In
–EXC
1
3
5
2
3
6
Surge
Suppression
and
Protection
+EXC
LPF
Isochopper™
Amplifier
Pat Pending
LPF
20
V
OUT
19
+V
–V
22
I/O Common
Precision
Reference
Isolated
Computer-Side
Power
RD EN\
Backpanel
Term Block
1
2
Temp
Sensor
CJC
+V
–V
17
Isolated
Field-Side
Power
Power
Oscillator
+5V
16
Power Common
FIGURE 1. SCM5B37 Block Diagram.
DATAFORTH
A Burr-Brown Company
®
Call 800-444-7644
For Information and Assistance
SPECIFICATIONS
Typical at T
Module
Input Range
Input Bias Current
Input Resistance
Normal
Power Off
Overload
Input Protection
Continuous
Transient
CMV, Input to Output
Continuous
Transient
CMR (50Hz or 60Hz)
NMR
Accuracy
(1)
Nonlinearity
Stability
Input Offset
Output Offset
Gain
Noise
Input, 0.1 to 10Hz
Output, 100kHz
Bandwidth, –3dB
Response Time, 90% Span
Output Range
Output Resistance
Output Protection
Output Selection Time
(to
±1mV
of V
OUT
)
Output Current Limit
Output Enable Control
Max Logic “0”
Min Logic “1”
Max Logic “1”
Input Current, “0”, “1”
Open Input Response
Open Input Detection Time
Cold Junction Compensation
Accuracy, 25°C
Accuracy, +5°C to +45°C
Accuracy, –40°C to +85°C
Power Supply Voltage
Power Supply Current
Power Supply Sensitivity
Mechanical Dimensions
Environmental
Operating Temp. Range
Storage Temp. Range
Relative Humidity
RFI Susceptibility
A
= +25°C and +5V power.
SCM5B37
-0.1V to +0.5V
-25nA
50MΩ
40kΩ
40kΩ
240Vrms max
ANSI/IEEE C37.90.1-1989
1500Vrms max
ANSI/IEEE C37.90.1-1989
160dB
95dB at 60Hz, 90dB at 50Hz
±0.05%
Span
±10µV
RTI
(2)
±0.02%
Span
±1µV/°C
(3)
±20µV/°C
±25ppm/°C
0.2µVrms
200µVrms
4Hz
0.2s
0V to +5V
50Ω
Continuous Short to Ground
6µs at C
load
= 0 to 2000pF
+8mA
+0.8V
+2.4V
+36V
0.5µA
Upscale
10s
±0.25°C
±0.5°C
±1.25°C
+5VDC
±5%
30mA
±2µV/%
RTI
(2)
2.28" x 2.26" x 0.60" (58mm x 57mm x 15mm)
–40°C to +85°C
–40°C to +85°C
0 to 95% Noncondensing
±0.5%
Span Error at 400MHz, 5W, 3ft
NOTES: (1) Includes nonlinearity, hysteresis
and repeatability. Does not include CJC
accuracy. (2) RTI = Referenced to input.
(3)This is equivalent to
°C
as follows: Type J
0.020
°C/°C,
Types K, T 0.025°C/°C,
Type E 0.016°C/°C, Types R, S 0.168°C/°C.
Type N 0.037°C/°C, Type C, 0.072°C/°C.
ORDERING
INFORMATION
MODEL
SCM5B37J
SCM5B37K
SCM5B37T
SCM5B37E
SCM5B37R
SCM5B37S
SCM5B37B
SCM5B37C
SCM5B37N
TYPE
Type J
Type K
Type T
Type E
Type R
Type S
Type B
Type C
Type N
INPUT RANGE
–100°C to +760°C (–148°F to +1400°F)
–100°C to +1350°C (–148°F to +2462°F)
–100°C to +400°C (–148°F to +752°F)
0°C to +900°C (+32°F to +1652°F)
0°C to +1750°C (+32°F to +3182°F)
0°C to +1750°C (+32°F to +3182°F)
0°C to +1800°C (+32°F to +3272°F)
+350°C to +1300°C (+662°F to +2372°F)
–100°C to +1300°C (–148°F to +2372°F)
OUTPUT RANGE
0V to +5V
0V to +5V
0V to +5V
0V to +5V
0V to +5V
0V to +5V
0V to +5V
OV to +5V
0V to +5V
Call 800-444-7644
For Information and Assistance
DATAFORTH
A Burr-Brown Company
®
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