5B38
GENERAL DESCRIPTION
bandwidth and yields optimal noise performance for accurate
The 5B38 is a wide-bandwidth single-channel signal
measurement of small signals in high electrical noise. A
chopper-stabilized input amplifier provides low drift and stable
gain.
conditioning module that interfaces, amplifies, and filters
signals from full-bridge and half-bridge strain-gage transducers
between 300Ω and 10kΩ. The module provides an isolated
bridge excitation of +10V and a protected, isolated precision
output of -5V to +5V. The 10 kHz bandwidth of the module
ideally suits to measure signals that vary rapidly with time, such
as strain on an automobile chassis during a crash test.
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. An
additional benefit, the output section acts as a third floating
port, eliminating possible problems from ground loops and
power-supply noise. The output common must be kept within
+3V of power common.
The 5B38 protects the computer side from damage due to field-
side over-voltage faults. The module withstands 240V rms at its
input terminals without damage, thereby shielding computer-
side circuitry from field-side over-voltage conditions. In
addition, the 5B38 is mix-and-match and hot-swappable with
all 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..
The 5B38-04 contains bridge completion circuitry, so can
function with half-bridge strain gages. For quarter-bridge
requirements, the user must complete the bridge input to the
half-bridge level externally. The factory can configure the
module for a wide range of input ranges (sensitivities).
A signle-pole anti-aliasing filter resides at each modules input.
A three-pole, low-pass filter in the output stage sets the
.
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Figure 2
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