5B47-CUSTOM AD [Analog Devices], 5B47-CUSTOM Datasheet - Page 2

• Manufacturer Part Number: 5B47-CUSTOM
• Description: Isolated, Linearized Thermocouple Input
• Manufacturer: AD [Analog Devices]

GENERAL DESCRIPTION
The 5B47 is a single-channel signal conditioning module that
interfaces, amplifies and filters J, K, T, E, R, S, and B-type
thermocouple. The module provides an isolated and protected
precision output of 0 to + 5 V.
The 5B47 internally linearizes its input signal to provide an
output that is linear with temperature. Accuracy for each type of
sensor is specified in the 5B47 model table. (See Model 5B37 for
non-linearized conditioning of thermocouple signals.)
Accurate and System-Ready - Internal cold-junction
compensation largely corrects errors arising from parasitic
thermocouples formed by thermocouple connection to the
input screw terminals, providing an accuracy of +0.25
+25
predictable upscale signal to indicate an open thermocouple; for
a downscale response, connect a 20MΩ, 0.25W resistor across
screw terminals 1 and 3.
The 5B47 protects the computer side from damage due to field-
side over-voltage faults. All models withstand 240V rms at their
input terminals without damage, thereby shielding computer-
side circuitry from field-side over-voltage conditions. Further,
the 5B47 is mix-and-match and hot-swappable with other 5B
Series modules, so can be inserted or removed from any socket
in the same backplane without disrupting system power.
Inside the 5B47 Module – A chopper-stabilized input amplifier
provides low drift and stable gain. At the amplifier input, a
.
o
C ambient temperature. The module generates a
o
C @
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Figure 2
stable, laser-trimmed zero-scale input voltage is subtracted from
the input signal to set the zero-scale value. For user
convenience, the zero can be optionally factory-set to meet
custom needs. This allows suppression of a zero-scale input
value many times larger than the total span for precise
expanded-scale measurements.
Internal multi-pole low-pass filtering with a 4-Hz cutoff (-3 dB)
provides 60 dB of normal-mode rejection (noise on signal) and
enhancement of common-mode rejection (noise on signal
return) at 60 Hz, enabling accurate measurement of small
signals in high electrical noise.
Signal isolation by transformer coupling uses a proprietary
modulation technique for linear, stable and reliable
performance. The differential input circuit on the field side is
fully floating, eliminating the need for any input grounding. 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. The
output common must be kept within +3 V of power common.
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.
.
5B47