Isolated Linearized 4-Wire RTD Input
5B35
FEATURES
Single-channel signal conditioning module that Amplifies,
Protects, Filters, and Isolates Analog Input.
Isolates and protects a wide variety of four-wire RTDs.
Generates an linearized, highly accurate output of 0 to +5V.
Module circuitry can withstand 240v rms at the input screw-
terminals.
All 5B35 series modules are mix-and-match and Hot
Swappable.
FUNCTIONAL BLOCK DIAGRAM
APPLICATIONS
Industrial signal conditioning
Industrial signal isolation
Industrial signal filtering
Signal Linearization
Figure 1. 5B35 Functional Block Diagram
There are also a number of backplanes and mounting sockets
which provide a complete signal conditioning solution for end
users. Each backplane incorporates screw terminals for field
wiring inputs and outputs and cold junction sensors for
thermocouple applications.
These signal conditioners are designed to provide an easy and
convenient solution to signal conditioning problems of both
designers and end users in measurement and control
applications. Typical uses include microcomputer-based
measurement systems, standard data acquisition systems,
programmable controllers, analog recorders and dedicated
control systems. The 5 B series modules are ideally suited to
applications where monitoring and control of temperature,
pressure, flow, rotation and other analog signals are required.
The 5B Series modules and backplanes are approved by Factory
Mutual (FM) and the 5B Series modules are approved by the
Canadian Standards Association (CSA) for use in Class 1,
Division 2, Groups A, B, C, and D locations. These approvals
certify that the 5B Series is suitable for use in locations where a
hazardous concentration of flammable gas may exist only under
fault conditions of operation. Equipment of this category is
called “nonincendive” and they need no special enclosures or
other physical safeguards. The 5B series modules and
backplanes have been tested and passed the stringent heavy
industrial requirements of the EU’s electromagnetic
compatibility (ENC) directive – EN50082-1 and EN50081-2.
When used according to installation directions (refer to 5B
series User Manual), any errors caused by EMI/RFI interference
will be less than 0.1% of the full scale 5B measurement range for
field strengths up to 10 V/M and frequencies up to 1 GHz.
PRODUCT OVERVIEW
The 5B Series represents an innovative generation of low cost,
high performance plug-in signal conditioners. Designed for
industrial applications, these modules incorporate highly
reliable transformer-based isolation and automated surface-
mount manufacturing technology. They are compact,
economical components whose performance exceeds that
available from more expensive devices. Combining 1500 V rms
continuous isolation, +0.05% calibrated accuracy, small size and
low cost, the 5B Series is an attractive alternative to expensive
signal conditioners and in-house designs
All modules are potted and identical in pin-out and size (2.27” x
2.32” x 0.595”). They can be mixed and matched, permitting
users to address their exact needs, and may be “hot swapped
without disturbing field wiring or power. The isolated input
modules provide 0 to +5V or +5V outputs and accept J, K, T, E,
R, S, N, or B type thermocouples.
These modules feature complete signal conditioning functions
including 240 V rms input protection, filtering, chopper
stabilized low drift +1 uV/oC amplification, 1500 V rms
isolation, and sensor excitation when required.
All modules feature excellent common mode rejection and
meet industrial transient surge withstand specifications.
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
© 2004 Analog Devices, Inc. All rights reserved.
5B35
GENERAL DESCRIPTION
The 5B35 is a single-channel signal conditioning module that
amplifies, filters, isolates and protects a wide variety of four-wire
RTDs. The module provides a linearized, highly accurate output
of 0 to +5V.
Accurate and Stable Performance
– The four-wire
configuration of the 5B35 supplies RTD excitation from a
precision, protected current source: two RTD wires carry the
excitation current and two wires serve as signal-input leads that
measure the voltage across the RTD. Because no excitation
current flows through the signal input leads, the length or
resistance of the leads creates little or no RTD measurement
error. A low-drift chopper-stabilized differential amplifier
allows use of very low excitation current to minimize error due
to RTD self heating. The amplifies low input offset drift of
+0.01
o
C/
o
C and gain drift of +30ppm/
o
C. Assure accuracy over
the full operating temperature range.
True Three-Port Isolation
– The floating, differential input
circuit on the field side eliminates the need for any input
grounding. Signal and power isolation by transformer coupling
uses a proprietary modulation technique for linear, stable and
reliable performance. 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 signal. True three-port isolation (Input-Output-Power)
.
includes common-mode rating of: 1500V rms between input
and output and input and power; 250V rms between power and
output – no return path is required between the power and
signal output commons.
Filtering and Protection
– An optimized five-pole Butterworth
filter (with a 4-Hz bandwidth) provides 116dB of normal-mode
rejection (noise on signal) at 60 Hz and 108 dB at 50 Hz. Output
noise is an exceptionally low 0.3 Mv p-p in a 100 kHz
bandwidth and 6 mV p-p in a 5 MHz bandwidth.
The 5B35 protects the computer side from damage due to field-
side over-voltage faults. The module withstands 240V rms at
the input terminals without damage, thereby shielding the
internal computer-side circuitry from field-side over-voltage
conditions. In addition, the 5B35 is mix-and-match and hot
swappable with all other 5B Series modules, so can be inserted
or removed from any socket in the same backplane without
disrupting system power.
A series output switch eliminates the need for external
multiplexing in many applications. The switch is turned on by
an active-low enable input. If the switch is to be on at all times,
the enable-input should be grounded to power common as it is
on the 5B01 and 5B08 backplanes.
.
Figure 2
Rev. 0 | Page 2 of 9
5B35
Output, 100 kHz Bandwidth
Output, 1 MHz Bandwidth
Output, 5 MHz Bandwidth
Bandwidth, -3 dB
Output Rise Time, 10% to 90% Span
100 µV rms (0.3 mV peak-peak)
1.5 mV peak-peak
6 mV peak-peak
4 Hz
100 ms
Common-Mode Voltage (CMV)
Input-to-Output, Continuous
Input-to-Power, Continuous
Output-to-Power, Continuous
2
Transient
1500 V rms, maximum
1500 V rms, maximum
250 V rms, maximum
ANSI/IEEE C37.90.1-1989
Common Mode Rejection (CMR)
1 kΩ Source Imbalance, 50/60 Hz
Normal Mode Rejection (NMR)
190 dB (180 dB, Model 5B35-04)
116 dB @ 60 Hz; 108 dB @ 50 Hz
Sensor Excitation Current
100
Ω
Pt, 120
Ω
Ni
10
Ω
Cu
0.25 mA
1.0 mA
Lead Resistance Effect
100
Ω
Pt, 120
Ω
Ni
10Ω Cu
±0.00001°C/Ω
±0.0001°C/Ω
Input Protection
Continuous
Transient
Output Resistance
Voltage Output Protection
Output Current Limit
Output Selection Time
240 V rms, maximum
ANSI/IEEE C37.90.1-1989
25
Ω
Continuous Short to Ground
±9 mA
6 µs to ±1 mV of V
out
@ C
load
= 0 to 2,000 pF
Output Enable Control
2
Max Logic "0"
Min Logic "1"
Max Logic "1"
Input Current "0", "1"
Power Supply Voltage
Power Supply Current
Power Supply Sensitivity, RTI
Mechanical Dimensions
+0.8 V
+2.4 V
+100 V
0.5 µA
+5 V dc ±5%
15 mA
±0.2°C/% of V
s
2.275" x 2.375" x 0.595"
(57.8 mm x 59.1 mm x 15.1 mm)
Environmental
Temperature Range
Rated Performance
-40°C to +85°C
Rev. 0 | Page 4 of 9
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