AD 3B39

Isolated Process Current Output
Interfaces, isolates, & filters a 0 to +10V or -10V to +10V
input signal and provides an isolated process current output
across loads of 0 to 850Ω..
Intended for high-accuracy process control and monitoring
applications requiring total galvanic isolation.
Module circuitry can withstand 220v rms at the output
All 3B39 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. 3B39 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.
modulation technique for linear, stable and reliable
performance. A demodulator on the output side of the signal
transformer recovers the original signal, which is then filtered
and converted to an accurate current output by a current (V-toI) converter output stage. Output protection enables the 3B39 to
withstand accidental connection to 220V rms power lines
without damage, isolating computer-side circuitry. The 3B39
provides total ground isolation and transient protection when
interfacing DACs to standard 4-20 mA current loops, common
requirement in microcomputer based control system.
The 3B39 is a single-channel signal conditioning current output
module that interfaces, isolates and filters a 0 to +10V or -10V
to +10V input signal and provides an isolated process current
output across loads of 0 to 850Ω. The output current appears at
the 3B Series backplane current output screw terminal block. It
is intended for high-accuracy process control and monitoring
applications requiring complete galvanic isolation and
protection against damage from transients and faults between
systems or separated system elements. Either of the two input
voltage ranges can be converted to either of the two output
current ranges via programming jumpers provided on the
bottom of the module. Model 3B39 features a nonlinearity of
+0.01% and an accuracy of +0.1%. Providing +1500V peak of
galvanic transformer based isolation output-to-input and power,
the 3B39 offers a common mode rejection (CMR) of 90 dB @
50/60 Hz to preserve the integrity of low level signals in noisy
environments. The 3B39 is mix-and-match and hot-swappable
with other 3B Series modules, so it can be inserted or removed
from any socket in the same backplane without disturbing
system power.
Signal isolation by transformer coupling uses a proprietary
Figure 2
Rev. 0 | Page 2 of 8
3B39 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)
Model 3B39
Input Voltage Standard Ranges
0 V to +10 V or -10 V to +10 V
-20 V to +20 V, maximum
Without Damage
Input Resistance
10 kΩ
Output Ranges
Standard Ranges (RL = 0 to 850Ω)
4 mA to 20 mA or 0 mA to 20 mA
Custom Ranges
Not Available
Initial @ +25°C
±0.1% Span + CJC Sensor Error
±0.01% Span
Stability vs. Temperature
Current Output
±25 ppm of Span/°C
±25 ppm of Reading/°C
Zero and Span Adjustment Range
±5% of Span
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
2 ms
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
90 dB
Output Protection
Continuous, Normal Mode
220 V rms, maximum
ANSI/IEEE C37.90.1-1989
Power Supply Voltages 3
±15 V dc Supplies
Rated Operation
±(11.5 V dc to 16.5 V dc)
±10 mA
±0.01% span/V
+24 V dc Loop Supply
Rated Operation
+12 V dc to +30 V dc
+27 mA @ lout = 20 mA
Rev. 0 | Page 3 of 8
Mechanical Dimensions
±0.0002% span/V
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
Input and Output Range may be selected using jumpers supplied.
Includes the combined effects of repeatability, hysteresis, and nonlinearity.
+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.
Specifications subject to change without notice.
Rev. 0 | Page 4 of 8
Figure 3 3B39 Input Field Connections
Figure 4 . Model 3B Series Module, with pin-out assignments.
Table 1. Pin Function Descriptions—
Pin No.
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.
Rev. 0 | Page 5 of 8
Figure 5. Outline Dimensions
Rev. 0 | Page 6 of 8
Rev. 0 | Page 7 of 8
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective companies.
Rev. 0 | Page 8 of 8