Isolated, Linearized Thermocouple Input 7B47 FUNCTIONAL BLOCK DIAGRAM FEATURES Interfaces, amplifies and filters input voltages from a J, K, T, E, R, S, B or N-type thermocouple. Module provides a precision output of either +1 V to +5 V or 0 V to +10 V, linear with input temperature. All 7B47 series modules are mix-and-match and Hot Swappable. APPLICATIONS Industrial signal conditioning Figure 1. 7B47 Functional Block Diagram Industrial signal isolation The modules feature a maximum nonlinearity of +0.02% and Industrial signal filtering are factory calibrated to guarantee a maximum accuracy specification of +0.1%. PRODUCT OVERVIEW The 7B Series offers up to 1500 V rms continuous common The 7B Series of signal conditioners feature small size, low cost mode voltage isolation and 120 V rms of field wiring input and a wide output voltage range for a variety of applications protection. The power supplies necessary to drive each of the including process control and factory-floor environments. The individual modules input circuitry are internally isolated, single-channel 7B modules accept inputs from a range of enabling the 7B Series modules to offer true channel-to-channel o transducers and are fully rated over the extended -40 C to isolation of the input signals. o +85 C industrial temperature range. All 7B Series modules are rated for a nominal power supply input of +24 VDC and, for The modules directly accept analog signals from maximum flexibility, they will accept supply voltages in the +14 thermocouples, RTDs, current loop powered transmitters, and VDC to +35 VDC range. The input modules, with the exception other process control signals. The 7B Series modules amplify, of the 7B21, provide a high-level output voltage that is factory linearize, isolate, protect and convert the transducer output configured for either the +1 V to +5 V or 0 V to +10 V range. signals to standardized analog inputs for high-level analog I/O The 7B21 is a unity gain, isolated input module with an subsystems. The 7B Series Subsystem consists of 19-inch rack- input/output range of +10V. Output modules are available that compatible hardware (model AC 1363), with universal provide either isolated process current or isolated bipolar mounting backplane and a family of plug-in (up to 16 per voltage output. Model 7B39 converts either a +1 V to +5 V input backplane) input and output signal conditioning modules. Four- to a 4 to 20 mA output or a 0 V to +10 V input to a 0-20 mA , eight-, and sixteen-channel backplanes are available. Each output. The input/output ranges of the 7B39 are factory backplane incorporates screw terminals for easy power configured. The 7B22 is a unity gain module that provides an connections and field wiring, and includes a 25-pin D-type isolated +10V output signal. All modules have a universal pin- connector for interfacing the high-level single-ended voltage out and may be readily hot-swapped under full power without outputs to the users equipment. Gold-plated sockets are disrupting field wiring. Each module accepts analog transducer provided on each channel of the backplane to ensure the signals and transfers them to a process control or factory data reliability of each modules electrical connection. collection system without the inherent noise, non-linearity, drift and extraneous voltages which frequently accompany the signals. 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. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Specifications subject to change without notice. No license is granted by implication Tel: 781.329.4700 www.analog.com or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective companies. Fax: 781.326.8703 2004 Analog Devices, Inc. All rights reserved. 7B47 GENERAL DESCRIPTION input temperature range. A current source provides the upscale The 7B47 is a single-channel signal conditioning module that open circuit indication. Amplitude modulation is used to interfaces, amplifies and filters input voltages from a J, K, T, E, R, implement transformer isolation (1500) V rms input-to-output S, B, or N-type thermocouple and provides an isolated and and power). Isolated front-end circuitry power is supplied by a protected precision output of either +1V to +5V or 0 to +10 V, DC/DC converter. The output section contains a demodulator, linear with input temperature. High accuracy internal cold linearizer. A two-pole low pass filter (-3 dB 3 Hz), a buffer junction compensation and a predictable upscale open circuit amplifier and a power oscillator. The two-pole output filter and indication provide a complete signal conditioning solution. To subsequent buffer ensures that a low noise, low impedance accurately measure low level signals in electrically noisy (<1 ) signal is available at the output to drive loads down to 2 environments, 1500 V rms of galvanic transformer-based k . isolation with a common mode rejection (CMR) of 160 of 160 dB 50/60 Hz and a normal mode rejection (NMR) of 60 dB 50/60 Hz are provided. Rated to operate with a nominal +24 VDC supply, Model 7B47 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 three input pins of model 7B47 are fully protected up to 120 V rms line voltages. A one-pole 3 Hz filter preconditions the thermocouple signal prior to amplification, provided by a low drift input amplifier. Cold junction compensation (CJC) is implemented using a thermistor temperature sensor embedded under the input screw terminal block on a 7B Series backplane. A voltage reference source acts to offset the thermocouple signal in accordance with the specified lower bound on the Figure 2 Rev. 0 Page 2 of 8