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Non Isolated, Linearized RTD Input
7B14
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
www.analog.com
Fax: 781.326.8703
2004 Analog Devices, Inc. All rights reserved.
FEATURES
Amplifies, Protects, Filters, and Isolates input voltages from
a wide variety of two and three-wire platinum, copper and
nickel Resistor Temperature Detectors (RTDs).
Module provides a precision output of either +1 V to +5 V or
0 V to +10 V, linear with temperature.
All 7B14 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 to
+85
o
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.
FUNCTIONAL BLOCK DIAGRAM
Figure 1. 7B14 Functional Block Diagram
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.
7B14
Rev. 0 | Page 2 of 8
GENERAL DESCRIPTION
The 7B14 is a low cost, single-channel signal conditioning
module that interfaces, amplifies and filters input voltages from
a wide variety of two-and three-wire platinum, copper and
nickel Resistor Temperature Detectors (RTDs) and provides a
precision output of either +1 V to +5 V or 0 V to +10 V, linear
with temperature. Model 7B14 features a nonlinearity of +0.05%
maximum (Pt and Cu RTDs). RTD excitation current, three-
wire lead resistance compensation and a predictable upscale
open circuit indication provide a complete signal conditioning
solution. Rated to operate with a nominal +24 VDC supply,
Model 7B14 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 7B14 are fully protected up to
+30 VDC. A 250 uA excitation current for platinum and nickel
RTDs and a 1mA excitation current for copper RTDs is
provided to create an input voltage to the 7B14. This current
also provides the upscale open circuit indication. A one-pole 3
Hz filter preconditions the RTD signal prior to amplification,
provided by a low drift input amplifier. The output section
contains a two-pole low pass filter (-3 dB @ 3 Hz) and a buffer
amplifier. The two-pole output filter and subsequent buffer
ensure that a low noise, low impedance (<1) signal is available
at the output to drive loads to 2 k minimum.
.
Figure 2













7B14
Rev. 0 | Page 3 of 8
7B14 Models Available
Model RTD
Sensor
(2- or 3-wire)
Input Range
Output Range
Nonlinearity
(maximum)
Accuracy
(maximum)
7B14-01-1
100
Pt, = 0.00385
-100C to +100C
+1 V to +5 V
0.05% span
0.15% span
7B14-01-2
100
Pt, = 0.00385
-100C to +100C
0 V to +10 V
0.05% span
0.15% span
7B14-02-1
100
Pt, = 0.00385
0C to +100C
+1 V to +5 V
0.05% span
0.2% span
7B14-02-2
100
Pt, = 0.00385
0C to +100C
0 V to +10 V
0.05% span
0.2% span
7B14-03-1
100
Pt, = 0.00385
0C to +200C
+1 V to +5 V
0.05% span
0.15% span
7B14-03-2
100
Pt, = 0.00385
0C to +200C
0 V to +10 V
0.05% span
0.15% span
7B14-04-1
100
Pt, = 0.00385
0C to +600C
+1 V to +5 V
0.05% span
0.1% span
7B14-04-2
100
Pt, = 0.00385
0C to +600C
0 V to +10 V
0.05% span
0.1% span
7B14-05-1
100
Pt, = 0.00385
-50C to +350C
+1 V to +5 V
0.05% span
0.1% span
7B14-05-2
100
Pt, = 0.00385
-50C to +350C
0 V to +10 V
0.05% span
0.1% span
Model
RTD Sensor
(2- or 3-wire)
Input Range
Output Range
Nonlinearity
(maximum)
Accuracy
(maximum)
7B14-C-02-1
10
Cu, = 0.004274
0C to +120C
(10
@ +25C)
+1 V to +5 V
0.05% span
1.0% span
7B14-C-02-2
10
Cu, = 0.004274
0C to +120C
(10
@ +25C)
0 V to +10 V
0.05% span
1.0% span
Model
RTD Sensor
(2- or 3-wire)
Input Range
Output Range
Nonlinearity
(maximum)
Accuracy
(maximum)
7B14-N-01-1
120
Ni, = 0.00672
0C to +300C
+1 V to +5 V
0.12% span
0.3% span
7B14-N-01-2
120
Ni, = 0.00672
0C to +300C
0 V to +10 V
0.12% span
0.3% span
7B14-N-02-1
120
Ni, = 0.00672
0C to +200C
+1 V to +5 V
0.14% span
0.3% span
7B14-N-02-2
120
Ni, = 0.00672
0C to +200C
0 V to +10 V
0.14% span
0.3% span

7B14 Specifications
(typical @ +23C 5C and V
s
= +24 V dc)
Description Model
7B14
Input Ranges
RTD Types
100
Platinum, 2-, 3-wire, =0.00385
120
Nickel, 2-, 3-wire, =0.00672
10
Copper, =0.004274
Temperature Ranges
Refer to Model Table
Custom Ranges
Not Available*
Output Range Options (R
L
> 2 k
)
+1 V to +5 V or 0 V to +10 V
Accuracy
1
Initial @ +25C
Refer to Model Table
7B14
Rev. 0 | Page 4 of 8
Nonlinearity
2
Refer to Model Table
Input Offset vs. Temperature
1 V/C
Zero Suppression vs. Temperature
0.002% (R
z
/R
span
)
3
/C
Span vs. Temperature
60 ppm/C
Output Offset vs. Temperature
0.002% Span/C
Lead Resistance Effect
0.02C/
Output Noise
5 MHz Bandwidth
1 mV peak
10 Hz to 100 Hz Bandwidth
0.4 mV rms
0.1 Hz to 10 Hz Bandwidth
0.6 V peak
Bandwidth, -3 dB
3 Hz
Output Rise Time
250 ms
Normal Mode Rejection @ 50/60 Hz
60 dB
Input Protection
30 V dc, continuous
Input Transient Protection
ANSI/IEEE C376.90.1-1989
IEEE-STD 472
IEC 255-4, Class II
Output Resistance
< 1
Voltage Output Protection
Continuous Short to Ground
Power Supply
Voltage Range, Operating
+14 V dc to +35 V dc
Current
+25 mA, maximum
Sensitivity 0.0001%/%
of
Vs
Mechanical Dimensions
1.663" x 2.11" x 0.563"
(42.24 mm x 53.6 mm x 14.3 mm)
Environmental
Temperature Range
Operating
-40C to +85C
Storage
-40C to +85C
Relative Humidity, 24 hours
0 to 90% @ +60C noncondensing
ESD Sensitivity
IEC 801-2, Level 2
RFI Susceptibility
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.
1
Includes the combined effects of repeatability, hysteresis, and nonlinearity.
2
Nonlinearity is calculated using best-fit straight line method.
3
Rz is the value of the RTD resistance at the lowest measurement point. R
span
is the change in resistance over the measurement span.
Specifications subject to change without notice.
7B14
Rev. 0 | Page 5 of 8
PIN CONFIGURATIONS AND FUNCTIONAL DESCRIPTIONS
Figure 3 7B14 Input Field Connections
Table 1. Pin Function Descriptions--
Pin
No.
Input Module Function
Output Module Function
0
SENSOR INPUT
NOT USED
1
INPUT HIGH
OUTPUT HIGH
2
INPUT LOW
OUTPUT LOW
3
POWER SUPPLY (DC)
POWER SUPPLY (DC)
4 OUTPUT
VOLTAGE INPUT
VOLTAGE
5
OUTPUT & POWER
COMMON
INPUT AND POWER
COMMON
Figure 4 . Model 7B Series Module, with pin-out assignments.
ESD CAUTION
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.