ANALOG DEVICES 7B41 Service Manual

Isolated, Voltage or Current Input

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FEATURES

Interfaces, amplifies and filters unipolar and bipolar voltage
inputs.

Module provides a precision output of either +1 V to +5 V or
0 V to +10 V.

All 7B41 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 -40

o

+85

C 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 pin­out 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.

o

C to

7B41

FUNCTIONAL BLOCK DIAGRAM

Figure 1. 7B41 Functional Block Diagram

The modules feature a maximum nonlinearity of +0.02% and
are factory calibrated to guarantee a maximum accuracy
specification of +

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 module’s 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 rack­compatible 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 module’s electrical connection.

0.1%.

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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.

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Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

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GENERAL DESCRIPTION

The 7B41 is a single-channel signal conditioning module that
interfaces, amplifies and filters unipolar and bipolar voltage
inputs and provides a protected precision output of either +1 V
to +5 V or 0 V to +10 V. Model 7B41 features a nonlinearity of
+

0.02% maximum and an accuracy of +0.1% maximum

(+

0.01% typical). 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 110 dB @ 50/60 Hz and a normal mode rejection
(NMR) of 100 dB @ 50/60 are provided. Rated to operate with
nominal +24 VDC supply, Model 7B41 is mix-and-match and
hot-swappable with other 7B Series input modules, so it an be
inserted or removed from any socket in the same backplane
without disturbing system power.

The floating differential input of Model 7B41 is fully protected
up to 240 V rms line voltage. A one-pole 10 KHz filter
preconditions the input signal prior to amplification by a low
drift input amplifier. Amplitude modulation is used to
implement transformer isolation (1500 V rms input-to-output

7B41

and power). Isolated front-end circuitry power is supplied by a
DC/DC converter. The output section contains a four pole low
pass filter (-3 dB @ 10KHz), a buffer amplifier and a power
oscillator. The two-pole output filter and subsequent buffer
ensures that a low noise, low impedance (<1Ω) signal is
available at the output to drive loads of 2 kΩ minimum.

Figure 2

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7B41 Models Available

Model Input Range Output Range

7B41-01-1 0-10V 1-5V

7B41-01-2 0-10V 0-10V

7B41-02-1 +/-5V 1-5V

7B41-02-2 +/-5V 0-10V

7B41-03-1 +/-10V 1-5V

7B41-03-2 +/-10V 0-10V

7B41-04-1 0-5V 1-5V

7B41-04-2 0-5V 0-10V

7B41-05-1 0-20V 1-5V

7B41-05-2 0-20V 0-10V

7B41-06-1 +/-20V 0-10V

7B41-07-1 0-50V 1-5V

7B41-07-2 0-50V 0-10V

7B41-08-1 +/-50V 1-5V

7B41-08-2 +/-50V 0-10V

7B41

7B41 Specifications
Wideband mV/V Isolated Input module (typical @ +25C and +24 Vdc)

Description Model 7B41

Range1

Standard Range +/- 5V to +/- 50V

Custom Ranges YES

Output Range Options (RL > 2 kΩ)

Accuracy2

Initial @25C 0.01% span (0.1% max)

Nonlinearity (BSL) +/-0.02% max

Input Ofs vs. Temp 0.5uV/C

Zero Suppression vs. Temp 0.002%Vz/C

Span vs. Temp +/-35ppm/C

Output Ofs vs. Temp +/-0.001% span

Input Bias Current +/- 100 pA

Input Resistance

Power On >1M Ohm

Power Off >1M Ohm

Overload >1M Ohm

Output Noise

5MHz Bandwidth 2mV peak

1-5V or 0-10V (1)

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