Analog Devices B42 Datasheet

Isolated, Process Current Input

FEATURES

Isolated Current Input.
Interfaces with two-wire transmitters, providing an isolated,

regulated 20 V supply voltage.
Measure process-current input signal of 4-20 mA .
Generates an output of +1 to +5V or +2 to 10V.
Module circuitry can withstand 240v rms at the input screw-

terminals.
All 5B42 series modules are mix-and-match and Hot

Swappable.

APPLICATIONS

Industrial signal conditioning
Industrial signal isolation
Industrial signal filtering

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 surface­mount 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.

5B42

Figure 1. 5B42 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, f low, 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
European Union’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.

FUNCTIONAL BLOCK DIAGRAM

Rev. 0

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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
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registered trademarks are the property of their respective companies.

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

www.analog.com

GENERAL DESCRIPTION

The 5B42 is a single-channel signal conditioning module that
interfaces with two-wire transmitters, providing an isolated,
regulated 20V supply voltage. The module filters and amplifies
the 4-to-20 mA process-current input to produce an accurately
scaled, low-noise low-impedance output of +1 to +5 V or +2 to
+10 V.

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 ratings of 1500 V 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.

Accurate and Stable Performance – The 5B42 maintains
accuracy over the wide operating temperature range of -40

o

C through design for low parameter drift. This enables the

+85
module to provide output offset drift of only +
drift of just +

Why an Internal Current Sense Resistor? – The 5B42 offers
significant advantages over signal conditioners that require an
external current sense resistor. First, an external resistor is not
protected from accidental connection to a 240 V rms power
line. Next, the external resistor tolerance must be added to the

.

25 ppm/oC

5 uV/oC and gain

o

C to

5B42

conditioners specified errors. In contrast, the 5B42 is calibrated
and specified with its internal 25Ω sense resistor. Further, the
5B42 signal input, loop supply and the sense resistor are all
protected against accidental application of excess voltages up to
240V rms. Finally, there is no need to install an external sense
resistor on the backplane, but if one is installed it will not affect
5B42 performance.

Filtering and Protection – The 5B42 contains an optimized
five-pole low-pass filter with a -3 dB bandwidth at 100Hz that
provides a low-overshoot step response and exceptionally low
noise of 200 uV pk-pk in a 100kHz bandwidth. Attenuation
(normal mode rejection) increases at a 90 dB/decade rate
beyond 100 Hz.

The module protects the computer side from damage due to
field-side over-voltage faults. The module withstands 240 V rms
at the input terminals without damage, thereby shielding the
internal computer-side circuitry from field-side over-voltage
conditions. In addition, the 5B42 is mix-and-match and hot­swappable 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

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5B42

5B42 Models Available

Model Input Range Output Range

5B42-01 4 mA to 20 mA +1 V to +5 V
5B42-02 4 mA to 20 mA +2 V to +10 V
5B42-Custom * *

* Custom Input/Output ranges are available.

5B42 Specifications
(typical @ +25°C and V

Description Model 5B42

Standard Ranges 4 mA to 20 mA (Refer to Model Table)
Custom Ranges 0 mA to 20 mA (Refer to Ordering Section)
Isolated Loop Supply Voltage 20 V @ 4 mA to 20 mA Input
Output Ranges (R

Initial @ +25°C ±0.05% Span ±4 µA RTI
Nonlinearity ±0.01% Span
Input Offset vs. Temperature ±0.5 µV/°C
Output Offset vs. Temperature ±5 µV/°C
Gain vs. Temperature ±0.0025% of Reading/°C
Input Sense Resistor2

Input, 0.1 Hz to 10 Hz Bandwidth 10 nA rms
Output, 100 kHz Bandwidth 200 µV peak-peak
Bandwidth, -3 dB 100 Hz
Output Step Rise Time, 10% to 90% Span 4 ms

Output-to-Input, Continuous 1500 V rms, maximum
Input-to-Power, Continuous 1500 V rms, maximum
Output-to-Power, Continuous3 250 V rms, maximum
Transient ANSI/IEEE C37.90.1-1989

1 k Ω Source Imbalance, 50/60 Hz
Normal Mode Rejection (NMR) -3 dB @ 100 Hz (90 dB per decade > 100 Hz)

Continuous 240 V rms, maximum
Transient ANSI/IEEE C37.90.1-1989

> 50 k Ω)

L

= +5 V dc)

s

Input Ranges

+1 V to +5 V; +2 V to +10 V

Accuracy1

25 Ω

Noise

Common-Mode Voltage (CMV)

Common Mode Rejection (CMR)

140 dB

Input, Excitation, and Sense Resistor Protection

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