AD 3B37-J-01

Isolated, Thermocouple Input
Interfaces, amplifies, & filters input voltages from a J, K, T, E,
R, S, or B-type thermocouple.
High accuracy internal cold junction compensation.
Module provides simultaneous precision voltage and
current outputs.
Current output withstands 130V rms without damage.
All 3B37 series modules are mix-and-match and Hot
Industrial signal conditioning
Industrial signal isolation
Industrial signal filtering
The 3B Series of Signal Conditioning I/o Subsystems provide a
low-cost, versatile method of transferring analog transducer
signals to a data acquisition, monitoring or control system
without the inherent noise, non-linearity, drift and extraneous
voltages. The modules are designed to directly accept analog
signals from Thermocouples, RTD’s, AC and DC Strain Gages,
Torque Transducers, Frequency Transducers, LVDTs, millivolt
or process current signals. The modules amplify, isolate,
linearize and convert the transducer output signals to
standardized analog inputs for high-level analog I/O
subsystems. The 3B Series Subsystem consists of a 10” relay
rack with universal mounting backplane and a family of plug-in
(up to 16 per rack) input and output signal conditioning
Eight and four channel backplanes are also available. Each
backplane incorporates screw terminals for sensor inputs and
current outputs and a 26-pin connector for high-level singleended voltage outputs to the user’s equipment.
The input modules feature complete signal conditioning
circuitry optimized for specific sensors or analog signals and
provide two simultaneous high-level analog outputs: 0 to +10V
(or +10V) and 4-20 mA (or 0-20 mA).
Figure 1. 3B37 Functional Block Diagram
Output modules accept 0 to +10V (or +10V) single-ended
signals and provide an isolated 4-20 mA (or 0-20 mA) process
signal. All modules feature a universal pin-out and may be
readily hot-swapped under full power and interchanged without
disrupting field wiring.
The Analog Devices 3B Series Signal Conditioning Subsystem is
designed to easily handle signal conditioning problems in
measurement and control applications. Some typical uses are in
microcomputer-based data acquisition systems, programmable
controllers, analog recorders, dedicated control systems, and any
other applications where monitoring of temperature, pressure,
flow and analog signals are required. Since each input module
features two simultaneous outputs, the voltage output can be
used to provide an input to a microprocessor-based data
acquisition or control system while the current output can be
used for analog transmission, operator interface, or an analog
backup system.
Each input module is a single-channel signal conditioner which
plugs into a socket on the backplane and accepts its signal from
the input screw terminals. All input modules provide input
protection, amplification and filtering of the input signal,
accuracy of +0.1%, low drift of +1 uV/oC (low-level input
modules), and feature two high-level analog outputs that are
compatible with most process instrumentation. The isolated
input modules also provide +1500 V peak isolation.
The choice of a specific 3B module depends upon the type of
input signal. Input modules are available to accept millivolt, volt,
process current, thermocouple, RTD, AC and DC strain gage,
frequency and LVDT inputs. The voltage output of each module
is available from the sysem I/O connector while the current
output is available on the output screw terminals.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
The 3B37 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 isolated simultaneous
voltage and current outputs 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 peak 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. The current output
withstands 130 V rms without damage and interfaces user
equipment through screw terminals located on the 3B Series
backplane. This plug-in, mix-and-match, hot-swappable module
is easily field calibrated via front-panel zero and span
adjustments for both voltage and current outputs.
Accurate and System Ready – Internal cold-junction
compensation largely corrects errors arising from parasitic
thermocouples formed by thermocouple connection to the
input screw terminals, providing an accuracy of +0.5oC over the
+5oC to +45oC ambient temperature range. The module
generates a predictable upscale signal to indicate an open
thermocouple; for a downscale response, connect a 47MΩ, 0.25
Watt resistor across screw terminals 2 and 4 on the 3B Series
3B Series Custom Ranging Program – Externallyprogrammable version Model 3B37-X-00, enable the user to
configure a special input range by using the optional plug-on
AC1310 ranging card, which houses user-supplied resistors to
determine zero and span. To facilitate selecting resistors, a
Windows program, 3B-Custom, calculates resistor values based
on the user-desired input/output ranges.
Inside the 3B37 Module – A chopper-stabilized low-drift input
amplifier assures stable long-term stability. At the amplifier
input, a zero-scale input voltage is subtracted from the input
signal to set the zero-scale value. For user convenience, the zero
and span optionally can be factory configured to meet custom
needs (Model 3B37-CUSTOM) or can be externally
programmed (Model 3B37-X-00) via user-supplied resistors
inserted in the optional AC1310 plug-on ranging card. Zero
suppression can exceed 100% of the input range. This enables
suppression of a zero-scale input value amny times larger that
the total span for precise expanded-scale measurements of a
selection portion of an input signal. The differential input
circuit on the field side is fully floating, eliminating the need for
any input grounding. Signal isolation by transformer coupling
users a proprietary modulation technique for linear, stable and
reliable performance. A demodulator on the computer side of
the signal transformer recovers the original signa, which is then
filtered and buffered to provide a low-noise, low-impedance
output voltage, this output also drives a voltage-to-current (V/I)
converter to provide a simultaneous current output for
interfacing versatility.
Figure 2
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3B37 Models Available
Input Type
Input Range
Output Ranges1
Type J, K, T, E, R, S, or B
Externally Programmable 2
0 V to +10 V & 0 mA to 20 mA
Type J
-100°C to +100°C (-148°F to +1400°F)
0 V to +10 V & 0 mA to 20 mA
Type K
-100°C to +1350°C (-148°F to +2462°F)
0 V to +10 V & 0 mA to 20 mA
Type T
-100°C to +400°C (-148°F to +752°F)
0 V to +10 V & 0 mA to 20 mA
Type E
0°C to +900°C (+32°F to +1652°F)
0 V to +10 V & 0 mA to 20 mA
Type R
0°C to +1750°C (+32°F to +3182°F)
0 V to +10 V & 0 mA to 20 mA
Type S
0°C to +1750°C (+32°F to +3182°F)
0 V to +10 V & 0 mA to 20 mA
Type B
0°C to +1800°C (+32°F to +3272°F)
0 V to +10 V & 0 mA to 20 mA
Type J, K, T, E, R, S, or B
Output current range may be user programmed to 4 mA to 20 mA using jumper supplied.
Requires AC1310 ranging card.
* Custom Input/Output ranges are available. Refer to configuration guide.
3B37 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)
Model 3B37
Input Ranges
Standard Ranges
Refer to Model Table
Custom Ranges
±5 mV to ±500 mV
Output Ranges
0 V to +10 V; -10 V to +10 V
Voltage (RL > 2 KΩ)
Current (RL = 0 to 850Ω)
4 mA to 20 mA or 0 mA to 20 mA
Maximum Current Output Span
0 mA to 31 mA
Initial @ +25°C
±0.1% Span + CJC Sensor Error
±0.01% Span
Stability vs. Temperature
Voltage Output
±25 ppm of Reading/°C
Current Output3
±25 ppm of Span/°C
±25 ppm of Reading/°C
Zero and Span Adjustment Range
Cold Junction Compensation (CJC)
±5% of Span
Initial Accuracy @ +25°C
±0.5 °C
Accuracy vs. Temperature, +5°C to +45°C
±0.5°C (±0.0125°C/°C)
Input Bias Current
+15 nA
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Input Resistance
15 MΩ
Input, 0.1 Hz to 10 Hz Bandwidth
0.2 µV rms
Output, 100 kHz Bandwidth
50 µV rms
Bandwidth, -3 dB
3 Hz
Output Rise Time, 10% to 90% Span
200 ms
Open Input Response
Open Input Detection Time
10 seconds
Common-Mode Voltage (CMV)
Input-to-Output, Continuous
±1500 V peak, maximum
ANSI/IEEE C37.90.1-1989
Common Mode Rejection (CMR)
1 kΩ Source Imbalance, 50/60 Hz
160 dB
Normal Mode Rejection, 50/60 Hz
60 dB
Input Protection
220 V rms maximum
ANSI/IEEE C37.90.1-1989
Voltage Output Protection
Continuous Short to Ground
Current Output Protection
130 V rms, continuous
Power Supply Voltages 6
±15 V dc Supplies
Rated Operation
±(11.5 V dc to 16.5 V dc)
±12 mA
±0.01% span/V
+24 V dc Loop Supply
Rated Operation
+12 V dc to +30 V dc
+27 mA @ lout = 20 mA
±0.0002% span/V
Mechanical Dimensions
3.15" x 3.395" x 0.775"
(80.0 mm x 86.2 mm x 19.7 mm)
Temperature Range
Rated Performance
-25°C to +85°C
-55°C to +85°C
Relative Humidity, 24 hours
0 to 95% @ +60°C noncondensing
RFI Susceptibility
±0.5% Span error @ 400 MHz, 5 Watt, 3 ft
For a 0 mA to 20 mA range, a typical minimum output current is 10 µA.
Includes the combined effects of repeatability, hysteresis, and nonlinearity.
With respect to the voltage output.
A wide range of custom zero suppression and span is available with the 3B30-00 and 3B31-00 models, using the AC1310 ranging card.
When used with the CJC temperature sensor provided on the 3B Series backplane.
+24 V dc loop power is required for driving the current output at loads up to 850Ω. If a current output load of 400Ω or less is applied, +15 V dc is sufficient for loop power. If only
voltage output is used, loop power is not required.
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Figure 3 3B37 Input Field Connections
Table 1. Pin Function Descriptions—
Pin No.
Figure 4 . Model 3B Series Module, with pin-out assignments.
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.
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Figure 5. Outline Dimensions
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© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective companies.
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