Analog Devices B27 Datasheet

Isolated Thermocouple Input

FEATURES

Interfaces, amplifies and filters input voltages from a J, K, T,
E, R, S or B-type thermocouple.

Provides an isolated and protected precision output of
either +1 V to +5 V or 0 V to +10 V.

Operates with a nominal +24 VDC supply.
All 7B27 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

C industrial temperature range. All 7B Series modules are

+85
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

7B27

FUNCTIONAL BLOCK DIAGRAM

Figure 1. 7B27 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%.

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.

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

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GENERAL DESCRIPTION

The 7B27 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 an isolated (up to
100 V rms) and protected precision output of either +1 V to +5
V or 0 V to +10V, linear with input voltage. High accuracy
internal cold junction compensation and a predictable upscale
open circuit indication provide a complete signal conditioning
solution. The 7B27 is mix-and-match and hot-swappable with
other 7B Series input modules, so can be inserted or removed
from any socket in the same backplane without disturbing
power. Model 7B27 is rated to operate with a nominal +24 VDC
supply.

The three input pins of Model 7B27 are protected up to +
VDC. A one-pole 3 Hz filter preconditions the thermocouple
signal prior to amplification, provided by a low drift input
amplifier. Cold junction compensation (CJC) is implemented
using a thermistor temperature sensor embedded under the
input screw terminal block on a 7B Series backplane. A voltage
reference source acts to offset the thermocouple signal in
accordance with the specified lower bound on the input
temperature range. A current source provides the upscale open

30

7B27

circuit indication. Amplitude modulation is used to implement
transformer isolation (100 V rms, continuous). Isolated front­end circuitry power is supplied by a DC/DC converter. The
output section contains a demodulator, a two-pole low pass
filter (-3 dB @ 3 Hz), 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 down to 2 kΩ.

Figure 2

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7B27 Models Available

Model Input Type Input Range Output Range

7B27-J-01-1
7B27-J-01-2
7B27-J-10-1
7B27-J-10-2
7B27-J-11-1
7B27-J-11-2
7B27-J-12-1
7B27-J-12-2
7B27-J-13-1
7B27-J-13-2
7B27-K-02-1
7B27-K-02-2
7B27-K-20-1
7B27-K-20-2
7B27-K-21-1
7B27-K-21-2
7B27-K-22-1
7B27-K-22-2
7B27-K-23-1
7B27-K-23-2
7B27-T-03-1
7B27-T-03-2
7B27-E-04-1
7B27-E-04-2
7B27-R-05-1
7B27-R-05-2
7B27-S-06-1
7B27-S-06-2
7B27-B-07-1
7B27-B-07-2

Type J -100°C to +100°C (-148°F to +1400°F) +1 V to +5 V
Type J -100°C to +100°C (-148°F to +1400°F) 0 V to +10 V
Type J 0°C to +200°C (+32°F to +392°F) +1 V to +5 V
Type J 0°C to +200°C (+32°F to +392°F) 0 V to +10 V
Type J 0°C to +400°C (+32°F to +752°F) +1 V to +5 V
Type J 0°C to +400°C (+32°F to +752°F) 0 V to +10 V
Type J 0°C to +600°C (+32°F to +1112°F) +1 V to +5 V
Type J 0°C to +600°C (+32°F to +1112°F) 0 V to +10 V
Type J +300°C to +600°C (+572°F to +1112°F) +1 V to +5 V
Type J +300°C to +600°C (+572°F to +1112°F) 0 V to +10 V
Type K -100°C to +1350°C (-148°F to +2462°F) +1 V to +5 V
Type K -100°C to +1350°C (-148°F to +2462°F) 0 V to +10 V
Type K 0°C to +300°C (+32°F to +572°F) +1 V to +5 V
Type K 0°C to +300°C (+32°F to +572°F) 0 V to +10 V
Type K 0°C to +600°C (+32°F to +1112°F) +1 V to +5 V
Type K 0°C to +600°C (+32°F to +1112°F) 0 V to +10 V
Type K 0°C to +1200°C (+32°F to +2192°F) +1 V to +5 V
Type K 0°C to +1200°C (+32°F to +2192°F) 0 V to +10 V
Type K +600°C to +1200°C (-148°F to +1400°F) +1 V to +5 V
Type K +600°C to +1200°C (-148°F to +1400°F) 0 V to +10 V
Type T -100°C to +400°C (-148°F to +752°F) +1 V to +5 V
Type T -100°C to +400°C (-148°F to +752°F) 0 V to +10 V
Type E 0°C to +900°C (+32°F to +1652°F) +1 V to +5 V
Type E 0°C to +900°C (+32°F to +1652°F) 0 V to +10 V
Type R 0°C to +1750°C (+32°F to +3182°F) +1 V to +5 V
Type R 0°C to +1750°C (+32°F to +3182°F) 0 V to +10 V
Type S 0°C to +1750°C (+32°F to +3182°F) +1 V to +5 V
Type S 0°C to +1750°C (+32°F to +3182°F) 0 V to +10 V
Type B 0°C to +1800°C (+32°F to +3272°F) +1 V to +5 V
Type B 0°C to +1800°C (+32°F to +3272°F) 0 V to +10 V

7B27

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