7B21

Isolated High Level Voltage Input 7B21 FEATURES Unity gain single-channel signal conditioning module that interfaces, filters, and isolates a +10 Volt input signal. Features a nonlinearity of +0.02% maximum and an accuracy of +0.1% maximum. All 7B21 series modules are mix-and-match and Hot Swappable. FUNCTIONAL BLOCK DIAGRAM APPLICATIONS Industrial signal conditioning Industrial signal isolation Industrial signal filtering Figure 1. 7B21 Functional Block Diagram PRODUCT OVERVIEW The 7B Series of signal conditioners feature small size, low cost and a wide output voltage range for a variety of applications including process control and factory-floor environments. The single-channel 7B modules accept inputs from a range of transducers and are fully rated over the extended -40oC to +85oC industrial temperature range. All 7B Series modules are rated for a nominal power supply input of +24 VDC; and, for maximum flexibility, they will accept supply voltages in the +14 VDC to +35 VDC range. The input modules, with the exception of the 7B21, provide a highlevel output voltage that is factory configured for either the +1 V to +5 V or 0 V to +10 V range. The 7B21 is a unity gain, isolated input module with an input/output range of +10V. Output modules are available that provide either isolated process current or isolated bipolar voltage output. Model 7B39 converts either a +1 V to +5 V input to a 4 to 20 mA output or a 0 V to +10 V input to a 0-20 mA output. The input/output ranges of the 7B39 are factory configured. The 7B22 is a unity gain module that provides an isolated +10V output signal. All modules have a universal pin-out and may be readily hotswapped under full power without disrupting field wiring. Each module accepts analog transducer signals and transfers them to a process control or factory data collection system without the inherent noise, non-linearity, drift and extraneous voltages which frequently accompany the signals. The modules feature a maximum nonlinearity of +0.02% and are factory calibrated to guarantee a maximum accuracy specification of +0.1%. The 7B Series offers up to 1500 V rms continuous common mode voltage isolation and 120 V rms of field wiring input protection. The power supplies necessary to drive each of the individual module’s input circuitry are internally isolated, enabling the 7B Series modules to offer true channel-to-channel isolation of the input signals. The modules directly accept analog signals from thermocouples, RTDs, current loop powered transmitters, and other process control signals. The 7B Series modules amplify, linearize, isolate, protect and convert the transducer output signals to standardized analog inputs for high-level analog I/O subsystems. The 7B Series Subsystem consists of 19-inch rackcompatible hardware (model AC 1363), with universal mounting backplane and a family of plug-in (up to 16 per backplane) input and output signal conditioning modules. Four, eight-, and sixteen-channel backplanes are available. Each backplane incorporates screw terminals for easy power connections and field wiring, and includes a 25-pin D-type connector for interfacing the high-level single-ended voltage outputs to the user’s equipment. Gold-plated sockets are provided on each channel of the backplane to ensure the reliability of each module’s electrical connection. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any 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 or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective companies. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. www.analog.com Tel: 781.329.4700 Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved. 7B21 GENERAL DESCRIPTION The 7B21 is a unity gain single-channel signal conditioning module that interfaces, filters and isolates a +10 Volt input signal and provides a protected precision output of +10 Volt. Model 7B21 features a nonlinearity of +0.02% maximum and an accuracy of +0.1% maximum (+0.01% typical). To accurately measure low level signals in electrically noisy environments, 1500 V rms of galvanic transformer-based isolation with a common mode rejection (CMR) of 100 dB @ 50/60 Hz is provided. Rated to operate with a nominal +24 VDC supply, Model 7B21 is mix-and-match and hot-swappable with other 7B Series input modules, so it can be inserted or removed from any socket in the same backplane without disturbing system power. The floating differential input of Model 7B21 is fully protected up to 120 V rms line voltage. A one-pole 300 Hz filter preconditions the input signal prior to a low drift differential input amplifier. Amplitude modulation is used to implement transformer isolation (1500 V rms input-to-output and power). Isolated front-end circuitry power is supplied by a DC/DC converter. The output section contains a two-pole low pass filter (-3 dB @ 300 Hz), a buffer amplifier and a power oscillator. The two-pole output filter and subsequent buffer ensures that a low noise, low impedance ( 2 kΩ) -10 V to +10 V Not Available* -10 V to +10 V Accuracy1 Initial @ +25°C Nonlinearity2 Input Offset vs. Temperature Span vs. Temperature Output Offset vs. Temperature Input Bias Current ±0.01% Span (±0.1% Span, maximum) ±0.02% Span, maximum N/A3 ±35 ppm/°C ±0.001% Span/°C 30 pA (200 pA, maximum) Input Resistance Power ON Power OFF 2 MΩ 30 kΩ, minimum Output Noise 5 MHz Bandwidth 10 Hz to 100 kHz Bandwidth 0.1 Hz to 10 Hz Bandwidth Bandwidth, -3 dB Output Rise Time, 10% to 90% Span 6 mV peak 1.5 mV rms 6 µV peak 300 Hz 1 ms Common-Mode Voltage (CMV) Input-to-Output and Power 1500 V rms continuous Common Mode Rejection (CMR) Input-to-Output and Power @ 50/60 Hz Input Protection Input Transient Protection 100 dB 120 V rms, continuous ±35 V dc, continuous ANSI/IEEE C376.90.1-1989 IEEE-STD 472 IEC 255-4, Class II