AD 3B46

Isolated Frequency Input
3B45 / 3B46
Interfaces, isolates, & filters frequency inputs.
The 3B45 accepts full-scale inputs from 25 to 1100 Hz
The 3B46 accepts full-scale inputs from 520 Hz to 25 kHz.
Modules provide simultaneous precision voltage and
current outputs.
Modules circuitry can withstand 130v rms at the input screwterminals.
All 3B45 & 3B46 series modules are mix-and-match and Hot
Figure 1. 3B45 & 3B46 Functional Block Diagram
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).
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.
3B45 / 3B46
selected threshold (Vt) and hysteresis (Vh). Signals of virtually
any wave shape that exceed the combined threshold and
hysteresis levels (Vt + Vh) will trigger a comparator at a rate
determined by the input frequency. The comparator output is
then transmitted across a proprietary transformer-coupled
isolation barrier. A demodulator on the computer side of the
signal transformer recovers the original signal, 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.
The 3B45 and 3B46 are single-channel isolated frequency input
moduels which produce simultaneous precision voltage and
current outputs proportional to input frequency. Model 3B45
accepts full-scale inputs ranging from 25 Hz to 1100 Hz, while
Model 3B46 accepts full-scale input from 520 Hz to 25kHz.
Both models enable the user to set the threshold to either 0 V
(for zero crossing signals) or +1.6 V (for positive level signals),
and the hysteresis to either 0 or +4 V. Hysteresis can be set for
any value within this range using the supplied AC1310 ranging
card. The 3B45 and 3B46 shield their computer side outputs
from damage and loss of signal integrity from field-side overvoltage faults, withstanding up to 220 V rms at their input
terminals. The current output withstands 130 V rms without
damage and interfaces user equipment through screw terminal
connections. In addition, all 3B45 and 3B46 models are plug-in,
mix-and-match and hot-swappable, so each can be inserted or
removed from any socket in the same backplane without
disrupting system power.
Setting the threshold value is a simple matter of externally
wiring to the 3B Series backplane screw terminals. The
threshold for measuring a zero-crossing voltage waveform (such
as sine waves) can be set to 0 volts by connecting terminal 3 to
terminal 4. The threshold for a positive level signal (such as a
TTL or pulse train waveform) can be set at +1.6 V by
connecting terminals 1 and 2. Hysteresis for both input signal
types is set at 0 V, but can be changed to +4V by removing the
jumper that is installed on the AC1310 ranging card shipped
with each unit.
3B Series Custom-Ranging Program – Externallyprogrammable Model 3B45-00 and 3B46-00 enable the user to
configure a special input range by using the supplied plug-on
AC1310 ranging card, which houses user-supplied resistors to
determine hysteresis, zero and span. To facilitate selecting
resistors, a Windows program, 3B-CUSTOM, calculates resistor
values based on the user-desired input/output ranges.
The 3B45 and 3B46 compare the input signal to the user.
Figure 2
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3B45 / 3B46
3B45 and 3B46 Models Available
Output Ranges1
Input Range
Step Response
Externally Programmable
0 Hz to 25 Hz
0 V to +10 V & 0 mA to 20 mA
1.6 sec
0 Hz to 300 Hz
0 V to +10 V & 0 mA to 20 mA
0.6 sec
0 V to +10 V & 0 mA to 20 mA
Input Range
Step Response
Output Ranges
Externally Programmable
0 kHz to 1.5 kHz
0 V to +10 V & 0 mA to 20 mA
0.07 sec
0 kHz to 3 kHz
0 V to +10 V & 0 mA to 20 mA
0.03 sec
0 kHz to 25 kHz
0 V to +10 V & 0 mA to 20 mA
0.03 sec
0 V to +10 V & 0 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.
3B45 and 3B46 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)
Model 3B45
Model 3B46
Input Ranges
Standard Ranges
Refer to Model Table
Refer to Model Table
Custom Ranges
25 Hz span, min : 1100 Hz span, max.
520 Hz span, min : 25 kHz span, max.
Output Ranges
Voltage (RL > 2 kΩ)
0 V to +10 V
Current (RL + 0 to 850 Ω)1
4 mA to 20 mA or 0 mA to 20 mA
0 mA to 31 mA
Maximum Current Output Span
Initial @ +25°C
±0.1% Span
±0.02% Span
Stability vs. Temperature
Voltage Output
Output Zero
±500 µV/°C
±50 ppm of Reading/°C
±25 ppm of Span/°C
±25 ppm of Reading/°C
Zero and Span Adjustment Range
±5% of Span
Input Bias Current
+3 nA
Current Output
Input Resistance
Small Signal, Vin < 4 V pk-pk
15 MΩ
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3B45 / 3B46
Large Signal, Vin > 4 V pk-pk
82 kΩ
Output, 100 kHz Bandwidth
75 µV rms
Output, Ripple
10 mV rms @ 10% Fspan, maximum
Output Step Response Time
Refer to Model Table
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
100 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 Voltages5
±15 V dc Supplies
Rated Operation
±(11.5 V dc to 16.5 V dc)
±16 mA
±19 mA
±0.01% span/V
Rated Operation
+13.5 V dc to +30 V dc
+27 mA @ lout = 20 mA
±0.0002% span/V
3.15" x 3.395" x 0.775"
(80.0 mm x 86.2 mm x 19.7 mm)
+24 V dc Loop Supply
Mechanical Dimensions
Temperature Range
Rated Performance
-25°C to +85°C
-55°C to +85°C
Relative Humidity
0 to 95% @ +60°C noncondensing
RFI Susceptibility
±0.5% Span error @ 400 MHz, 5
Watt, 3 ft
* Specifications same as model 3B45.
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 3B45-00 and 3B46-00 models, 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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3B45 / 3B46
Figure 3 3B45 & 3B46 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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3B45 / 3B46
Figure 5. Outline Dimensions
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3B45 / 3B46
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3B45 / 3B46
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective companies.
Rev. 0 | Page 8 of 8