Model 5B36 converts the input from a variety of potentiometers and variable resistors to a high level output of 0 V to +5 V. The module provides transformer isolation, potentiometer excitation, signal
filtering and input protection against line voltage connection. The series output switch eliminates the need for external multiplexing. The industry standard 5B Series encapsulated plug-in modular package is compatible with all 5B backplanes. Modules are powered by +5 V dc, ± 5%.
Signal isolation is provided by transformer coupling using a proprietary technique for linear, stable performance. A demodulator on the output side of the signal transformer recovers the input signal, which is filtered and buffered to provide an accurate, low impedance, low noise output.
True three-port isolation includes common-mode voltage of: 1500 V rms between input and output, and between input and power; 250 V rms between output and power.
The modules provide potentiometer excitation from a precision current source. A low drift, chopper stabilized, differential amplifier design allows for the use of very low excitation currents to minimize accuracy losses from self-heating of the potentiometer. The low gain drift of ±30 ppm/°C and low offset drift assure that accuracy is maintained over a wide operating temperature range.
The 5B36 supplies equal excitation currents to three-wire potentiometers to cancel the effects of lead resistance.
An optimized five-pole Butterworth filter (with 4 Hz bandwidth) provides 116 dB of normal-mode rejection at 60 Hz and 108 dB at 50 Hz. Output noise is an exceptionally low 0.3 mV p-p at 100 kHz bandwidth and 6 mV p-p at 5 MHz bandwidth.
The input circuit is protected against accidental application of voltages, such as an ac power line, up to 240 V rms continuous.
A series output switch is included to eliminate the need for external multiplexing in many applications. This switch has a low output resistance and is controlled by an active-low enable input. When the output switch is not used, ground the enable input to I/O common to turn on the switch.
