ANALOG DEVICES 3B45, 3B46 Service Manual

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Isolated Frequency Input

3B45 / 3B46

FEATURES	FUNCTIONAL BLOCK DIAGRAM

Interfaces, isolates, & filters frequency inputs.

The 3B45 accepts full-scale inputs from 25 to 1100 Hz The 3B46 accepts full-scale inputs from 520 Hz to 25 kHz.

Modules provide simultaneous precision voltage and current outputs.

Modules circuitry can withstand 130v rms at the input screwterminals.

All 3B45 & 3B46 series modules are mix-and-match and Hot Swappable.

APPLICATIONS

Industrial signal conditioning Industrial signal isolation Industrial signal filtering

PRODUCT OVERVIEW

Figure 1. 3B45 & 3B46 Functional Block Diagram

Output modules accept 0 to +10V (or +10V) single-ended signals and provide an isolated 4-20 mA (or 0-20 mA) process signal. All modules feature a universal pin-out and may be readily hot-swapped under full power and interchanged without disrupting field wiring.

		The Analog Devices 3B Series Signal Conditioning Subsystem is
	MacshbM
The 3B Series of Signal Conditioning I/o Subsystems provide		designed to easily handle ignal conditioning pro lems in
low-cost, versatile method of transferring analog transducer		measurement and control applications. Some typical uses are in
signals to a data acquisition, monitoring or control system		mi ro omputer-ba ed data acquisition systems, programmable
inherent noise, non-linearity, drift and extraneous		mi ro omputer-ba ed data acquisition systems, programmable
inherent noise, non-linearity, drift and extraneous		controllers, analog recorders, dedicated control systems, and any
without the
voltages. The modules are designed to directly accept analog		other applications where monitoring of temperature, pressure,
signals from Thermocouples, RTD’s, AC and DC Strain Gages,		flow and analog signals are required. Since each input module
Torque Transducers, Frequency Transducers, LVDTs, millivolt		features two simultaneous outputs, the voltage output can be
or process current signals. The modules amplify, isolate,		used to provide an input to a microprocessor-based data
linearize and convert the transducer output signals to		acquisition or control system while the current output can be
standardized analog inputs for high-level analog I/O		used for analog transmission, operator interface, or an analog
subsystems. The 3B Series Subsystem consists of a 10” relay		backup system.
rack with universal mounting backplane and a family of plug-in		Each input module is a single-channel signal conditioner which
(up to 16 per rack) input and output signal conditioning
modules.		plugs into a socket on the backplane and accepts its signal from
Eight and four channel backplanes are also available. Each		the input screw terminals. All input modules provide input
Eight and four channel backplanes are also available. Each		protection, amplification and filtering of the input signal,
backplane incorporates screw terminals for sensor inputs and		accuracy of +0.1%, low drift of +1 uV/ oC (low-level input
current outputs and a 26-pin connector for high-level single-		modules), and feature two high-level analog outputs that are
ended voltage outputs to the user’s equipment.		compatible with most process instrumentation. The isolated
The input modules feature complete signal conditioning		input modules also provide +1500 V peak isolation.
The input modules feature complete signal conditioning
circuitry optimized for specific sensors or analog signals and		The choice of a specific 3B module depends upon the type of
provide two simultaneous high-level analog outputs: 0 to +10V		input signal. Input modules are available to accept millivolt, volt,
(or +10V) and 4-20 mA (or 0-20 mA).		process current, thermocouple, RTD, AC and DC strain gage,
		frequency and LVDT inputs. The voltage output of each module

is available from the system I/O connector while the current output is available on the output screw terminals.

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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.

3B45 / 3B46

selected threshold (Vt) and hysteresis (Vh). Signals of virtually any wave shape that exceed the combined threshold and hysteresis levels (Vt + Vh) will trigger a comparator at a rate determined by the input frequency. The comparator output is then transmitted across a proprietary transformer-coupled isolation barrier. A demodulator on the computer side of the signal transformer recovers the original signal, which is then filtered and buffered to provide a low-noise, low-impedance output voltage; this output also drives a voltage-to-current (V/I) converter to provide a simultaneous current output for interfacing versatility.

Setting the threshold value is a simple matter of externally wiring to the 3B Series backplane screw terminals. The threshold for measuring a zero-crossing voltage waveform (such as sine waves) can be set to 0 volts by connecting terminal 3 to terminal 4. The threshold for a positive level signal (such as a TTL or pulse train waveform) can be set at +1.6 V by connecting terminals 1 and 2. Hysteresis for both input signal types is set at 0 V, but can be changed to +4V by removing the jumper that is installed on the AC1310 ranging card shipped

GENERAL DESCRIPTION

The 3B45 and 3B46 are single-channel isolated frequency input moduels which produce simultaneous precision voltage and current outputs proportional to input frequency. Model 3B45 accepts full-scale inputs ranging from 25 Hz to 1100 Hz, while Model 3B46 accepts full-scale input from 520 Hz to 25kHz. Both models enable the user to set the threshold to either 0 V (for zero crossing signals) or +1.6 V (for positive level signals), and the hysteresis to either 0 or +4 V. Hysteresis can be set for any value within this range using the supplied AC1310 ranging card. The 3B45 and 3B46 shield their computer side outputs from damage and loss of signal integrity from field-side overvoltage faults, withstanding up to 220 V rms at their input terminals. The current output withstands 130 V rms without damage and interfaces user equipment through screw terminal connections. In addition, all 3B45 and 3B46 models are plug-in, mix-and-match and hot-swappable, so each can be inserted or removed from any socket in the same backplane without disrupting system power.

3B Series Custom-Ranging Program – Externallyprogrammable Model 3B45-00 and 3B46-00 enable the user to configure a special input range by using the supplied plug-on

AC1310 ranging card, which houses user-supplied resistors to

values based on the user-desired input/output ranges.

determine hysteresis, zero and span. To facilitate selectingMacshbMwith e unit. resistors, a Windows program, 3B-CUSTOM, calculates resistor

The 3B45 and 3B46 compare the input signal to the user-

Figure 2

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			3B45 / 3B46

3B45 and 3B46 Models Available
Model	Input Range	Output Ranges1	Step Response
3B45-00	Externally Programmable2	0 V to +10 V & 0 mA to 20 mA
3B45-01	0 Hz to 25 Hz	0 V to +10 V & 0 mA to 20 mA	1.6 sec
3B45-02	0 Hz to 300 Hz	0 V to +10 V & 0 mA to 20 mA	0.6 sec
3B45-Custom	*	*
Model	Input Range	Output Ranges1	Step Response
3B46-00	Externally Programmable2	0 V to +10 V & 0 mA to 20 mA
3B46-01	0 kHz to 1.5 kHz	0 V to +10 V & 0 mA to 20 mA	0.07 sec
3B46-02	0 kHz to 3 kHz	0 V to +10 V & 0 mA to 20 mA	0.03 sec
3B46-03	0 kHz to 25 kHz	0 V to +10 V & 0 mA to 20 mA	0.03 sec
3B46-Custom	*	*

1Output current range may be user programmed to 4 mA to 20 mA using jumper supplied.

2Requires AC1310 ranging card.

* Custom Input/Output ranges are available. Refer to configuration guide.

3B45 and 3B46 Specifications

(typical @ +25°C and ±15 V dc, and +24 V dc Power)

Description	Model 3B45	Model 3B46
MacshbM
	Input R nges
Standard Ranges	Refer to odel Table	Refer to Model Ta le
Custom Ranges	25 Hz span, min : 1100 Hz span, max.	520 Hz span, min : 25 kHz span, max.
	Output Ranges
Voltage (RL > 2 kΩ)	0 V to +10 V	*
Current (RL + 0 to 850 Ω)1	4 mA to 20 mA or 0 mA to 20 mA	*
Maximum Current Output Span	0 mA to 31 mA	*
	Accuracy2
Initial @ +25°C	±0.1% Span	*
Nonlinearity	±0.02% Span	*
	Stability vs. Temperature
Voltage Output
Output Zero	±500 µV/°C	*
Span	±50 ppm of Reading/°C	*
Current Output3
Zero	±25 ppm of Span/°C	*
Span	±25 ppm of Reading/°C	*
Zero and Span Adjustment Range4	±5% of Span	*
Input Bias Current	+3 nA	*
	Input Resistance
Small Signal, Vin < 4 V pk-pk	15 MΩ	*

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