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Isolated, Thermocouple Input

7B37

FEATURES

Interfaces, amplifies, and filters input voltages from a J, K, T,

E, R, S, or B-type thermocouple.

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

0 V to +10 V, linear with temperature.

High accuracy internal cold junction compensation.

All 7B37 series modules are mix-and-match and Hot

Swappable.

FUNCTIONAL BLOCK DIAGRAM

APPLICATIONS

Industrial signal conditioning

Industrial signal isolation

Industrial signal filtering

Figure 1. 7B37 Functional Block Diagram

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

C to

+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 pin-

out 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.

The modules feature a maximum nonlinearity of +0.02% and

are factory calibrated to guarantee a maximum accuracy

specification of +0.1%.

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 rack-

compatible 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.

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.

www.analog.com

Tel: 781.329.4700

Fax: 781.326.8703

7B37

GENERAL DESCRIPTION

The 7B37 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 and

protected precision output of either +1 V to +5 V or 0 V to +10

V, linear with input voltage. High accuracy internal cold

junction compensation and a predictable upscale open circuit

indication provide a complete signal conditioning solution. 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 160 dB @

50/60 Hz and a normal mode rejection (NMR) of 60 dB @

50/60 Hz are provided. Rated to operate with a nominal +24

VDC supply, Model 7B37 is mix-and-match and hot-swappable

with other 7B Series input modules, so it can be inserted or

removed from any socket in the same backplane without

disturbing system power.

The three input pins of Model 7b37 are fully protected up to

120 V rms line voltages. 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 circuit indication. Amplitude modulation is used to

implement transformer isolation (1500 V rms input-to-output

and power). Isolated front-end circuitry power is supplied by a

DC/DC converter. The output section contains a demodulator, a

two-pole low pass filter (-3 dB @ 3Hz), 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 to 2kΩ minimum.

Figure 2

Rev. 0 | Page 2 of 8

7B37

7B37 Models Available

Model

7B37-J-01-1

7B37-J-01-2

7B37-J-10-1

7B37-J-10-2

7B37-J-11-1

7B37-J-11-2

7B37-J-12-1

7B37-J-12-2

7B37-J-13-1

7B37-J-13-2

7B37-K-02-1

7B37-K-02-2

7B37-K-20-1

7B37-K-20-2

7B37-K-21-1

7B37-K-21-2

7B37-K-22-1

7B37-K-22-2

7B37-K-23-1

7B37-K-23-2

7B37-T-03-1

7B37-E-04-1

7B37-E-04-2

7B37-R-05-1

7B37-R-05-2

7B37-S-06-1

7B37-S-06-2

7B37-B-07-1

7B37-B-07-2

Input Type

Type J

Type K

Type T

Type E

Type R

Type S

Type B

Input Range

-100°C to +100°C (-148°F to +1400°F)

0°C to +200°C (+32°F to +392°F)

0°C to +400°C (+32°F to +752°F)

0°C to +600°C (+32°F to +1112°F)

+300°C to +600°C (+572°F to +1112°F)

-100°C to +1350°C (-148°F to +2462°F)

0°C to +300°C (+32°F to +572°F)

0°C to +600°C (+32°F to +1112°F)

0°C to +1200°C (+32°F to +2192°F)

+600°C to +1200°C (-148°F to +1400°F)

-100°C to +400°C (-148°F to +752°F)

0°C to +900°C (+32°F to +1652°F)

0°C to +1750°C (+32°F to +3182°F)

0°C to +1800°C (+32°F to +3272°F)

Output Range

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

+1 V to +5 V

0 V to +10 V

Rev. 0 | Page 3 of 8

7B37

7B37 Specifications

(typical @ +23°C ±5°C and Vs = +24 V dc)

Description

Input Range1

Thermocouple Types

Standard Temperature Ranges

Custom Ranges

Output Range Options (R

> 2 kΩ)

J, K, T, E, R, S, B

Refer to Model Table

Not Available*

+1 V to +5 V or 0 V to +10 V

Accuracy

Initial @ +25°C

Nonlinearity

Input Offset vs. Temperature

Zero Suppression vs. Temperature

Span vs. Temperature

Output Offset vs. Temperature

±0.01% Span (±0.1% Span, maximum)

±0.02% Span, maximum

±0.5 µV/°C

±0.005% (V

)

/°C

±35 ppm/°C

±0.002% Span/°C

Cold Junction Compensation

Accuracy

, over +5°C to +45°C ambient

Input Bias Current

±1.0°C

+25 nA

Input Resistance

Power ON

Power OFF

10 MΩ

30 kΩ, minimum

Output Noise

5 MHz Bandwidth

10 Hz to 100 kHz Bandwidth

0.1 Hz to 10 Hz Bandwidth

Bandwidth, -3 dB

Output Rise Time, 10% to 90% Span

6 mV peak

0.4 mV rms

0.6 µV peak

3 Hz

150 ms

Common-Mode Voltage (CMV)

Input-to-Output and Power

1500 V rms, continuous

Common Mode Rejection (CMR)

Input-to-Output and Power @ 50/60 Hz

Normal Mode Rejection @ 50/60 Hz

Input Protection

Input Transient Protection

160 dB

60 dB

120 V rms, continuous

±35 V dc, continuous

ANSI/IEEE C376.90.1-1989

IEEE-STD 472

IEC 255-4, Class II

Ω

Continuous Short to Ground

Model 7B37

Output Resistance

Voltage Output Protection

Rev. 0 | Page 4 of 8

7B37

Power Supply

Voltage Range, Operating

Current

Sensitivity

Mechanical Dimensions

Weight

+14 V dc to +35 V dc

+25 mA, maximum

±0.0001%/% of Vs

1.663" x 2.11" x 0.563"

(42.24 mm x 53.6 mm x 14.3 mm)

60 grams

Environmental

Temperature Range

Operating

Storage

Relative Humidity, 24 hours

ESD Sensitivity

RFI Susceptibility

-40°C to +85°C

0 to 90% @ +60°C non-condensing

IEC 801-2, Level 2

±0.5% Span error @ 400 MHz, 5 Watt, 3 ft

Warm-up time required to meet specifications is approximately 10 minutes.

* Contact factory for OEM requirements.

1Includes the combined effects of repeatability, hysteresis, and nonlinearity.

2Nonlinearity is calculated using best-fit straight line method.

3Vz is the nominal input voltage that results in a 0 V output.

4When used with the CJC temperature sensor provided on each channel of 7B Series backplanes.

Specifications subject to change without notice.

Rev. 0 | Page 5 of 8