AD 3B32-02

Isolated, Process Current Input
Interfaces, amplifies, & filters a process-current input.
Process-current input signals are measured by reading the
voltage across an external precision 100Ω resistor (supplied
with module).
Module provides simultaneous precision voltage and
current outputs.
Module circuitry can withstand 220v rms at the input screwterminals.
All 3B32 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. 3B32 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 system 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.
assures long-term stability. At the amplifier input, a stable,
zero-scale input voltage is subtracted from the input signal to
set the zero-scale value. Zero suppression can exceed 100% of
the input range. This is ideal for expanded-scale applications
requiring high-resolution measurement of a selected portion of
an input signal. For user convenience, the zero and span can be
factory configured to meet custom range needs (Model 3B32CUSTOM) or can be externally programmed (Model 3B32-00)
via user supplied resistors inserted in the optional AC1310 plugon ranging card. Internal low-pass filtering with a 3Hz cutoff (3dB) two-pole Butterworth filter enhances both 60 dB normalmode and 160 dB common-mode rejection at 50/60 Hz,
enabling accurate measurement of small signals in high
electrical noise.
The 3B32 is a single-channel signal conditioning module that
interfaces, amplifies and filters a process-current input and
provides simultaneous precision output voltage and current.
Process-current input signals are measured by reading the
voltage across an external precision 100Ω resistor (supplied).
Model 3B32 performs complete signal conditioning, including
isolating (+1500V peak input-to-output and power) and
protecting their computer side outputs from damage and loss of
signal integrity, and shielding their inputs from damage from
field-side over-voltage faults up to 220V rms. The current
output withstands 130V rms without damage and interfaces
user equipment through screw terminals located on the 3B
Series backplane. Each 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.
Signal isolation is accomplished by transformer coupling with a
proprietary modulation technique for linear, stable and reliable
performance. The differential input circuit on the field side is
fully floating, eliminating the need for any input grounding. A
demodulator on the computer side of the signal transformer
recovers the original signal, which is then filtered and buffered
and drives a voltage-to-current converter to provide the current
3B Series Custom-Ranging Program – Externallyprogrammable Model 3B32-00, enables 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.
A chopper-stabilized low-drift (+1uV/oC) input amplifier
Figure 2
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3B32 Models Available
Input Range
Output Ranges1
Externally Programmable2
-10 V to ±10 V & 0 mA to 20 mA
4 mA to 20 mA
0 V to ±10 V & 4 mA to 20 mA
0 mA to20 mA
0 V to ±10 V & 4 mA to 20 mA
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.
3B32 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)
Model 3B32
Input Ranges
Standard Ranges
0 mA to 20 mA; 4 mA to 20 mA
Custom Ranges
0 mA to 20 mA (refer to ordering section)
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
±0.01% Span
Stability vs. Temperature
Voltage Output
±25 ppm of Span/°C
Current Output
±25 ppm of Reading/°C
±25 ppm of Span/°C
±25 ppm of Reading/°C
Zero and Span Adjustment Range
±5% of Span
Input Resistor
100 Ω
Stability vs. Temperature
Input Bias Current
+3 nA
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Input Resistance (Module)
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
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 5
±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
±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 non-condensing
RFI Susceptibility
±0.5% Span error @ 400 MHz, 5 Watt, 3 ft
For a 0 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 3B32-00 model, using the AC1310 ranging card.
+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.
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Figure 3 3B32 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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