Isolated, Thermocouple Input
7B37
Rev. 0
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FEATURES
Interfaces, amplifies, and filters input voltages from a J, K, T,
E, R, S, or B-type thermocouple.
Module provides a precision output of either +1 V to +5 V or
0 V to +10 V, linear with temperature.
High accuracy internal cold junction compensation.
All 7B37 series modules are mix-and-match and Hot
Swappable.
APPLICATIONS
Industrial signal conditioning
Industrial signal isolation
Industrial signal filtering
PRODUCT OVERVIEW
The 7B Series of signal conditioners feature small size, low cost
and a wide output voltage range for a variety of applications
including process control and factory-floor environments. The
single-channel 7B modules accept inputs from a range of
transducers and are fully rated over the extended -40oC to
+85oC industrial temperature range. All 7B Series modules are
rated for a nominal power supply input of +24 VDC; and, for
maximum flexibility, they will accept supply voltages in the +14
VDC to +35 VDC range. The input modules, with the exception
of the 7B21, provide a high-level output voltage that is factory
configured for either the +1 V to +5 V or 0 V to +10 V range.
The 7B21 is a unity gain, isolated input module with an
input/output range of +10V. Output modules are available that
provide either isolated process current or isolated bipolar
voltage output. Model 7B39 converts either a +1 V to +5 V input
to a 4 to 20 mA output or a 0 V to +10 V input to a 0-20 mA
output. The input/output ranges of the 7B39 are factory
configured. The 7B22 is a unity gain module that provides an
isolated +10V output signal. All modules have a universal pin-
out and may be readily hot-swapped under full power without
disrupting field wiring. Each module accepts analog transducer
signals and transfers them to a process control or factory data
collection system without the inherent noise, non-linearity, drift
and extraneous voltages which frequently accompany the
signals.
FUNCTIONAL BLOCK DIAGRAM
Figure 1. 7B37 Functional Block Diagram
The modules feature a maximum nonlinearity of +0.02% and
are factory calibrated to guarantee a maximum accuracy
specification of +0.1%.
The 7B Series offers up to 1500 V rms continuous common
mode voltage isolation and 120 V rms of field wiring input
protection. The power supplies necessary to drive each of the
individual modules input circuitry are internally isolated,
enabling the 7B Series modules to offer true channel-to-channel
isolation of the input signals.
The modules directly accept analog signals from
thermocouples, RTDs, current loop powered transmitters, and
other process control signals. The 7B Series modules amplify,
linearize, isolate, protect and convert the transducer output
signals to standardized analog inputs for high-level analog I/O
subsystems. The 7B Series Subsystem consists of 19-inch rack-
compatible hardware (model AC 1363), with universal
mounting backplane and a family of plug-in (up to 16 per
backplane) input and output signal conditioning modules. Four-
, eight-, and sixteen-channel backplanes are available. Each
backplane incorporates screw terminals for easy power
connections and field wiring, and includes a 25-pin D-type
connector for interfacing the high-level single-ended voltage
outputs to the user’s equipment. Gold-plated sockets are
provided on each channel of the backplane to ensure the
reliability of each modules electrical connection.
7B37
Rev. 0 | Page 2 of 8
GENERAL DESCRIPTION
The 7B37 is a single-channel signal conditioning module that
interfaces, amplifies and filters input voltages from a J, K, T, E, R,
S, or B-type thermocouple and provides an isolated and
protected precision output of either +1 V to +5 V or 0 V to +10
V, linear with input voltage. High accuracy internal cold
junction compensation and a predictable upscale open circuit
indication provide a complete signal conditioning solution. To
accurately measure low level signals in electrically noisy
environments, 1500 V rms of galvanic transformer-based
isolation with a common mode rejection (CMR) of 160 dB @
50/60 Hz and a normal mode rejection (NMR) of 60 dB @
50/60 Hz are provided. Rated to operate with a nominal +24
VDC supply, Model 7B37 is mix-and-match and hot-swappable
with other 7B Series input modules, so it can be inserted or
removed from any socket in the same backplane without
disturbing system power.
The three input pins of Model 7b37 are fully protected up to
120 V rms line voltages. A one-pole 3 Hz filter preconditions
the thermocouple signal prior to amplification, provided by a
low drift input amplifier. Cold junction compensation (CJC) is
implemented using a thermistor temperature sensor embedded
under the input screw terminal block on a 7B Series backplane.
A voltage reference source acts to offset the thermocouple
signal in accordance with the specified lower bound on the
input temperature range. A current source provides the upscale
open circuit indication. Amplitude modulation is used to
implement transformer isolation (1500 V rms input-to-output
and power). Isolated front-end circuitry power is supplied by a
DC/DC converter. The output section contains a demodulator, a
two-pole low pass filter (-3 dB @ 3Hz), a buffer amplifier and a
power oscillator. The two-pole output filter and subsequent
buffer ensures that a low noise, low impedance (<1) signal is
available at the output to drive loads to 2k minimum.
Figure 2
7B37
Rev. 0 | Page 3 of 8
7B37 Models Available
Model Input Type Input Range Output Range
7B37-J-01-1 Type J -100°C to +100°C (-148°F to +1400°F) +1 V to +5 V
7B37-J-01-2 Type J -100°C to +100°C (-148°F to +1400°F) 0 V to +10 V
7B37-J-10-1 Type J 0°C to +200°C (+32°F to +392°F) +1 V to +5 V
7B37-J-10-2 Type J 0°C to +200°C (+32°F to +392°F) 0 V to +10 V
7B37-J-11-1 Type J 0°C to +400°C (+32°F to +752°F) +1 V to +5 V
7B37-J-11-2 Type J 0°C to +400°C (+32°F to +752°F) 0 V to +10 V
7B37-J-12-1 Type J 0°C to +600°C (+32°F to +1112°F) +1 V to +5 V
7B37-J-12-2 Type J 0°C to +600°C (+32°F to +1112°F) 0 V to +10 V
7B37-J-13-1 Type J +300°C to +600°C (+572°F to +1112°F) +1 V to +5 V
7B37-J-13-2 Type J +300°C to +600°C (+572°F to +1112°F) 0 V to +10 V
7B37-K-02-1 Type K -100°C to +1350°C (-148°F to +2462°F) +1 V to +5 V
7B37-K-02-2 Type K -100°C to +1350°C (-148°F to +2462°F) 0 V to +10 V
7B37-K-20-1 Type K 0°C to +300°C (+32°F to +572°F) +1 V to +5 V
7B37-K-20-2 Type K 0°C to +300°C (+32°F to +572°F) 0 V to +10 V
7B37-K-21-1 Type K 0°C to +600°C (+32°F to +1112°F) +1 V to +5 V
7B37-K-21-2 Type K 0°C to +600°C (+32°F to +1112°F) 0 V to +10 V
7B37-K-22-1 Type K 0°C to +1200°C (+32°F to +2192°F) +1 V to +5 V
7B37-K-22-2 Type K 0°C to +1200°C (+32°F to +2192°F) 0 V to +10 V
7B37-K-23-1 Type K +600°C to +1200°C (-148°F to +1400°F) +1 V to +5 V
7B37-K-23-2 Type K +600°C to +1200°C (-148°F to +1400°F) 0 V to +10 V
7B37-T-03-1 Type T -100°C to +400°C (-148°F to +752°F) +1 V to +5 V
7B37-T-03-1 Type T -100°C to +400°C (-148°F to +752°F) 0 V to +10 V
7B37-E-04-1 Type E 0°C to +900°C (+32°F to +1652°F) +1 V to +5 V
7B37-E-04-2 Type E 0°C to +900°C (+32°F to +1652°F) 0 V to +10 V
7B37-R-05-1 Type R 0°C to +1750°C (+32°F to +3182°F) +1 V to +5 V
7B37-R-05-2 Type R 0°C to +1750°C (+32°F to +3182°F) 0 V to +10 V
7B37-S-06-1 Type S 0°C to +1750°C (+32°F to +3182°F) +1 V to +5 V
7B37-S-06-2 Type S 0°C to +1750°C (+32°F to +3182°F) 0 V to +10 V
7B37-B-07-1 Type B 0°C to +1800°C (+32°F to +3272°F) +1 V to +5 V
7B37-B-07-2 Type B 0°C to +1800°C (+32°F to +3272°F) 0 V to +10 V
7B37
Rev. 0 | Page 4 of 8
7B37 Specifications
(typical @ +23°C ±5°C and Vs = +24 V dc)
Description Model 7B37
Input Range1
Thermocouple Types J, K, T, E, R, S, B
Standard Temperature Ranges Refer to Model Table
Custom Ranges Not Available*
Output Range Options (RL > 2 k) +1 V to +5 V or 0 V to +10 V
Accuracy1
Initial @ +25°C ±0.01% Span (±0.1% Span, maximum)
Nonlinearity2 ±0.02% Span, maximum
Input Offset vs. Temperature ±0.5 µV/°C
Zero Suppression vs. Temperature ±0.005% (Vz)3/°C
Span vs. Temperature ±35 ppm/°C
Output Offset vs. Temperature ±0.002% Span/°C
Cold Junction Compensation
Accuracy4, over +5°C to +45°C ambient ±1.0°C
Input Bias Current +25 nA
Input Resistance
Power ON 10 M
Power OFF 30 k, minimum
Output Noise
5 MHz Bandwidth 6 mV peak
10 Hz to 100 kHz Bandwidth 0.4 mV rms
0.1 Hz to 10 Hz Bandwidth 0.6 µV peak
Bandwidth, -3 dB 3 Hz
Output Rise Time, 10% to 90% Span 150 ms
Common-Mode Voltage (CMV)
Input-to-Output and Power 1500 V rms, continuous
Common Mode Rejection (CMR)
Input-to-Output and Power @ 50/60 Hz 160 dB
Normal Mode Rejection @ 50/60 Hz 60 dB
Input Protection 120 V rms, continuous
±35 V dc, continuous
Input Transient Protection ANSI/IEEE C376.90.1-1989
IEEE-STD 472
IEC 255-4, Class II
Output Resistance < 1
Voltage Output Protection Continuous Short to Ground
7B37
Rev. 0 | Page 5 of 8
Power Supply
Voltage Range, Operating +14 V dc to +35 V dc
Current +25 mA, maximum
Sensitivity ±0.0001%/% of Vs
Mechanical Dimensions 1.663" x 2.11" x 0.563"
(42.24 mm x 53.6 mm x 14.3 mm)
Weight 60 grams
Environmental
Temperature Range
Operating -40°C to +85°C
Storage -40°C to +85°C
Relative Humidity, 24 hours 0 to 90% @ +60°C non-condensing
ESD Sensitivity IEC 801-2, Level 2
RFI Susceptibility ±0.5% Span error @ 400 MHz, 5 Watt, 3 ft
Warm-up time required to meet specifications is approximately 10 minutes.
* Contact factory for OEM requirements.
1Includes the combined effects of repeatability, hysteresis, and nonlinearity.
2Nonlinearity is calculated using best-fit straight line method.
3Vz is the nominal input voltage that results in a 0 V output.
4When used with the CJC temperature sensor provided on each channel of 7B Series backplanes.
Specifications subject to change without notice.
7B37
Rev. 0 | Page 6 of 8
PIN CONFIGURATIONS AND FUNCTIONAL DESCRIPTIONS
Figure 3 7B37 Input Field Connections
Table 1. Pin Function Descriptions—
Pin
No.
Input Module Function Output Module Function
0 SENSOR INPUT NOT USED
1 INPUT HIGH OUTPUT HIGH
2 INPUT LOW OUTPUT LOW
3 POWER SUPPLY (DC) POWER SUPPLY (DC)
4 OUTPUT VOLTAGE INPUT VOLTAGE
5 OUTPUT & POWER
COMMON
INPUT AND POWER
COMMON
Figure 4 . Model 7B Series Module, with pin-out assignments.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human
body and test equipment and can discharge without detection. Although this product features proprietary ESD
protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges.
Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
7B37
Rev. 0 | Page 7 of 8
OUTLINE DIMENSIONS
Figure 5. Outline Dimensions
7B37
Rev. 0 | Page 8 of 8
NOTES
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective companies.
D05178-0-10/04(0)