3B32 Analog Devices, 3B32 Datasheet - Page 2

• Manufacturer Part Number: 3B32
• Description: Isolated/ Process Current Input
• Manufacturer: Analog Devices

GENERAL DESCRIPTION
The 3B32 is a single-channel signal conditioning module that
interfaces, amplifies and filters a process-current input and
provides simultaneous precision output voltage and current.
Process-current input signals are measured by reading the
voltage across an external precision 100Ω resistor (supplied).
Model 3B32 performs complete signal conditioning, including
isolating (+1500V peak input-to-output and power) and
protecting their computer side outputs from damage and loss of
signal integrity, and shielding their inputs from damage from
field-side over-voltage faults up to 220V rms. The current
output withstands 130V rms without damage and interfaces
user equipment through screw terminals located on the 3B
Series backplane. Each plug-in, mix-and-match, hot-swappable
module is easily field calibrated via front-panel zero and span
adjustments for both voltage and current outputs.
3B Series Custom-Ranging Program – Externally-
programmable Model 3B32-00, enables the user to configure a
special input range by using the optional plug-on AC1310
ranging card, which houses user-supplied resistors to determine
zero and span. To facilitate selecting resistors, a Windows
program, 3B-CUSTOM, calculates resistor values based on the
user-desired input/output ranges.
A chopper-stabilized low-drift (+1uV/
.
o
C) input amplifier
Rev. 0 | Page 2 of 8
Figure 2
assures long-term stability. At the amplifier input, a stable,
zero-scale input voltage is subtracted from the input signal to
set the zero-scale value. Zero suppression can exceed 100% of
the input range. This is ideal for expanded-scale applications
requiring high-resolution measurement of a selected portion of
an input signal. For user convenience, the zero and span can be
factory configured to meet custom range needs (Model 3B32-
CUSTOM) or can be externally programmed (Model 3B32-00)
via user supplied resistors inserted in the optional AC1310 plug-
on ranging card. Internal low-pass filtering with a 3Hz cutoff (-
3dB) two-pole Butterworth filter enhances both 60 dB normal-
mode and 160 dB common-mode rejection at 50/60 Hz,
enabling accurate measurement of small signals in high
electrical noise.
Signal isolation is accomplished by transformer coupling with 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
and drives a voltage-to-current converter to provide the current
output.
.
3B32