7B31 Isolated, Voltage Input

Introduction

7b31-01-1The 7B31 is a single-channel signal conditioning module that interfaces, amplifies and filters unipolar and bipolar voltage inputs and provides a protected precision output of either +1 V to +5 V or 0 V to +10 V. Model 7B31 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 120 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 V DC supply, Model 7B31 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.

Inside the 7B31 Series Module

The floating differential input of Model 7B31 is fully protected up to 120 V rms line voltage. A one-pole 3 Hz filter preconditions the input signal prior to amplification by a low drift input (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 @ 3Hz), 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 of 2 kΩ minimum.

Input and Output Ranges

7b31_fbd 

 Figure 1. FB31 Functional Block Diagram

7b31fcd

Figure 2. 7B31 Input Field Connections


Input Types  Output Options 
±5 V to ±50 V
+1 V to +5 V
0 V to +10 V


View and Order Models

  Model
Input Range  Output Range 
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7B31-01-1
0 V to +10 V
+1 V to +5 V
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7B31-01-2  0 V to +10 V 0 V to +10 V
Order Now  7B31-02-1  -5 V to +5 V  +1 V to +5 V 
Order Now  7B31-02-2  -5 V to +5 V 0 V to +10 V 
Order Now  7B31-03-1  -10 V to +10 V +1 V to +5 V 
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7B31-03-2 -10 V to +10 V  0 V to +10 V 
Order Now  7B31-04-1 0 V to +5 V  +1 V to +5 V
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7B31-04-2  0 V to +5 V  0 V to +10 V
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7B31-05-1  0 V to +20 V  +1 V to +5 V
Order Now  7B31-05-2 0 V to +20 V  0 V to +10 V 
Order Now  7B31-06-1 -20 V to +20 V  +1 V to +5 V 
Order Now  7B31-06-2  -20 V to +20 V  0 V to +10 V 
Order Now  7B31-07-1  0 V to +50 V  +1 V to +5 V 
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7B31-07-2  0 V to +50 V  0 V to +10 V
Order Now  7B31-08-1 -50 V to +50 V  +1 V to +5 V 
Order Now  7B31-08-2 -50 V to +50 V  0 V to +10 V 




































Specifications

7B31 Specifications
(typical @ +23°C ±5°C and Vs = +24 V dc)

 Description
Model 7B31 
Input Ranges 
(Refer to Model Table) 
Standard Unipolar Ranges 0 V to: +5 V or +10 V or +20 V or +50 V
Standard Bipolar Ranges ±5 V or ±10 V or ±20 V or ±50 V
Custom Ranges  Not Available*
Output Range Options (RL > 2 kΩ)
+1 V to +5 V or 0 V to +10 V
 Accuracy1
Initial @ +25°C
±0.01% Span (±0.1% Span, maximum)
Nonlinearity2 ±0.02% Span, maximum
Input Offset vs. Temperature  ±0.5 µV/°C 
Zero Suppression vs. Temperature  ±0.005% (Vz)3/°C
Span vs. Temperature  ±35 ppm/°C
Output Offset vs. Temperature  ±0.002% span/°C
 Input Resistance
Power ON
7B31-01 to 7B31-04  100 kΩ
7B31-05 to 7B31-08
1 MΩ 
Power OFF 30 kΩ, 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
3 µV peak
Bandwidth, -3 dB 3 Hz
Output Rise Time, 10% to 90% Span
150 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
120 dB
Normal Mode Rejection @ 50/60 Hz
120 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
Output Resistance  < 1 Ω
Voltage Output Protection Continuous Short to Ground 
 Power Supply
Voltage Range, Operating +14 V dc to +35 V dc
Current
+25 mA, maximum
Sensitivity
±0.0001%/% of Vs
Mechanical Dimensions 1.663" x 2.11" x 0.563
(42.24 mm x 53.6 mm x 14.3 mm)
Weight 60 grams
 Environmental
Temperature Range
  Operating -40°C to +85°C
  Storage -40°C to +85°C
Relative Humidity, 24 hours
0 to 90% @ +60°C noncondensing
ESD Sensitivity
IEC 801-2, Level 2
RFI Susceptibility ±0.5% Span error @ 400 MHz, 5 Watt, 3 ft

Warm-up time required to meet specifications is approximately 10 minutes.
* Contact factory for OEM requirements.
1 Includes the combined effects of repeatability, hysteresis, and nonlinearity.
2 Nonlinearity is calculated using best-fit straight line method.
3 Vz is the nominal input voltage that results in a 0 V output.
Specifications subject to change without notice.