ANALOG DEVICES 7B32 Service Manual

Isolated Process Current Input

7B32

FEATURES	FUNCTIONAL BLOCK DIAGRAM
Interfaces, amplifies and filters a process-current input .
Module provides a precision output of either +1 V to +5 V or
0 V to +10 V, linear with temperature.
Process-current input signals are measured by reading the
voltage across an internal 200Ωprotected resistor.
All 7B32 series modules are mix-and-match and Hot
Swappable.
Industrial signal conditioning
Industrial signal isolation	The modules feature a maximum nonlinearity of +0.02% and
Industrial signal filtering
	are factory calibrated to guarantee a maximum accuracy
PRODUCT OVERVIEW	specification of +0.1%.

	including process control and factory-floor environments. The
	MacshbM
	single-channel 7B modules accept inputs from a range of	individual module’s input circuitry are internally isolated,
	transducers and are fully rated over the extended -40oC to	enabling the 7B Series modules to offer true channel-to-channel
	+85oC industrial temperature range. All 7B Series modules are	isolation of the input ignals.
	The 7B Series of signal conditioners feature small size, low cost	The 7B Series offers up to 1500 V rms continuous common
	and a wide output voltage range for a variety of applications	mode voltage isolation and 120 V rms of field wiring input
		protection. The power supplies necessary to drive each of the
	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 user’s 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 module’s electrical connection.
	collection system without the inherent noise, non-linearity, drift
	and extraneous voltages which frequently accompany the
	signals.
	APPLICATIONS	Figure 1. 7B32 Functional Block Diagram
	Rev. 0
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7B32

GENERAL DESCRIPTION

The 7B32 is a single-channel signal conditioning module that interfaces, amplifies and filters a process-current input and provides a protected precision output voltage of either +1V to +5 V or 0 V to +10 V. Process-current input signals are measured by reading the voltage across an internal 200Ω protected resistor. Model 7B32 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 105 dB @ 50/60 Hz is provided. Rated to operate with a nominal +24 VDC supply, Model 7B32 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 current input of Model 7B32 is fully protected up to 120 V rms line voltage. A one-pole 100 Hz filter preconditions the voltage signal across the 200W protected input resistor prior to amplification by a low drift 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 @ 100 Hz), a buffer amplifier and a power oscillator. The two-pole output filter and subsequent buffer ensures that a low noise, low impedance (<1Ω) signal is available at the output to drive loads to 2 kΩ minimum

MacshbM

Figure 2

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7B32

7B32 Models Available

Model	Input Range	Output Range
7B32-01-1	+4 mA to +20 mA	+1 V to +5 V
7B32-01-2	0 mA to +20 mA	0 V to +10 V

7B32 Specifications

(typical @ +23°C ±5°C and Vs = +24 V dc)

Description

Model 7B32

Input Range1

Standard Ranges

Custom Ranges

Output Range Options (RL > 2 kΩ)

4 mA to 20 mA; 0 mA to 20 mA (Refer to Model Table)

Not Available*

+1 V to +5 V or 0 V to +10 V

Accuracy1

Input Offset vs.	MacshbM
Initial @ +25°C		±0.01% Span (±0.1% Span, maximum)
Nonlinearity2		±0.02% Span, maximum
Temperature		N/A3
Span vs. Temperature		±35 ppm/°C
Output Offset vs. Temperature		±0.003% Span/°C
		Input Resistance
Power ON		200 Ω
Power OFF		200 Ω, minimum
		Output Noise
5 MHz Bandwidth		6 mV peak
10 Hz to 100 kHz Bandwidth		0.4 mV rms
0.1 Hz to 10 Hz Bandwidth		4 µV peak
Bandwidth, -3 dB		100 Hz
Output Rise Time, 10% to 90% Span		10 ms
		Common-Mode Voltage (CMV)
Input-to-Output and Power		1500 V ms, continuous
		Common Mode Rejection (CMR)
Input-to-Output and Power @ 50/60 Hz		105 dB
Input Protection		120 V rms, continuous
		±35 V dc, continuous
Input Transient Protection		ANSI/IEEE C376.90.1-1989
		IEEE-STD 472
		IEC 255-4, Class II

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