5B45/5B46 ISOLATED, FREQUENCY INPUT



Functional Description

5B45-05/46-01 The 5B45 and 5B46 are single-channel isolated frequency input modules that produce a 0 to +5 V output proportional to input frequency. Model 5B45 accepts full-scale inputs ranging from 500 Hz to 20 kHz. Model 5B46 accepts full-scale inputs ranging from 20 kHz to 275 kHz. Both models allow the user to set the threshold to either 0 V (for zero crossing signals) or +1.4 V (for positive level signals), and the hysteresis to either ±25 mV or ±400 mV (all input types).

The 5B45 and 5B46 protect the computer side from field-side overvoltage faults. All models withstand 240 V rms at their input terminals without damage, thereby shielding computer-side circuitry from field-side overvoltage conditions. In addition, all 5B45 and 5B46 models are mix-and-match and hot-swappable, so can be inserted or removed from any socket in the same backplane without disrupting system power.

Inside 5B45/5B46 Modules
The 5B45/46 internal circuitry compares the input signal to the user-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 and converted to a high-level analog signal. This signal is then filtered by a multi-pole low pass Butterworth filter and buffered to provide a low-noise, low-impedance output signal that is accurately proportional to input frequency.

Simple Setup and Versatile Choices
Setting the threshold and hysteresis values is a simple matter of externally wiring to the backplane screw terminals. The threshold for measuring a zero-crossing voltage waveform (such as sine waves) is set to 0 volts by connecting the input signal across screw-terminals 4 and 3. The threshold for a positive level signal (such as a TTL or pulse train waveform) is set at +1.4 V by connecting the input signal across terminals 3 and 2. Hysteresis for both input signal types is set at ±400 mV, but can be changed to ±25 mV by adding a jumper between screw terminals 1 and 4.

Response time is a function of a modules rated input frequency range. (See the 5B45 and 5B46 Model Table).

Convenience Features
The input circuit is fully floating and isolated from the output and power commons. In addition, the output section acts as a third floating port towards eliminating possible problems from ground loops and power supply noise. The output common must be held within ±3 V of power common.

A series output switch eliminates the need for external multiplexing in many applications. The switch is turned on by an active-low enable input. The enable input should be grounded to power common if the output need not be switched as it is on the 5B01 and 5B08 backplanes.



5B45/5B46 FBD

Figure 1. 5B45 and 5B46 Functional Block Diagram

 

Input Ranges

5B45: 0 to 10 kHz
(0 to 20 kHz - custom)

5B46: 0 to 250 kHz
(0 to 275 kHz - custom)

Output Ranges

0 V to +5 V
(-5 V to +5 V - custom)

  
5B45/5B46 IFC
Figure 2. 5B45 and 5B46 Input Field Connections


5B45 and 5B46 Models Available
  Model Input Range Output Range Rise/Fall Time Step Response
Order Now 5B45-010 Hz to 500 Hz 0 V to +5 V 80 ms 150 ms
Order Now 5B45-02 0 Hz to 1 kHz 0 V to +5 V 60 ms 140 ms
Order Now 5B45-03 0 Hz to 2.5 kHz 0 V to +5 V 50 ms 130 ms
Order Now 5B45-04 0 Hz to 5 kHz 0 V to +5 V 50 ms 130 ms
Order Now 5B45-05 0 Hz to 10 kHz 0 V to +5 V 50 ms 130 ms
  5B45-Custom * *    

 

  Model Input Range Output Range Rise/Fall Time Step Response
Order Now 5B46-01 0 Hz to 25 kHz 0 V to +5 V 15 ms 44 ms
Order Now 5B46-02 0 Hz to 50 kHz 0 V to +5 V 7 ms 22 ms
Order Now 5B46-03 0 Hz to 100 kHz 0 V to +5 V 4 ms 12 ms
Order Now 5B46-04 0 Hz to 250 kHz 0 V to +5 V 4 ms 9 ms
  5B46-Custom **    
* Custom Input/Output ranges are available. Refer to configuration guide.

5B45 and 5B46 Specifications
Description Model 5B45 Model 5B46
Frequency Input
Standard Ranges Refer to Model Table Refer to Model Table
Custom Ranges 500 Hz span, min.; 20 kHz span, max. 20 kHz span, min.; 275 kHz span, max.
Overrange 20% of Span *
Voltage Range 70 mV rms min. 240 V rms max. *
Waveforms Sine, Square, Triangle, Pulse Train *
   Pulse Width (Pulse Train Inputs) 2 µs min. *
Threshold Options Zero Crossing or TTL (+1.4 V) *
   TTL Input, Low (-40°C to +85°C) 0.8 V max. *
   TTL Input, High (-40°C to +85°C) 2.0 V min. *
Hysteresis Options1 ±25 mV or ±400 mV *
Output Ranges (RL > 50 kΩ) -5 V to +5 V or 0 V to +5 V *
Accuracy2
Initial @ +25°C ±0.05% Span (±0.1% Span, max.) *
Nonlinearity ±0.005% Span (±0.015% Span, max.) *
Output Offset vs. Temperature ±20 µV/°C *
Gain vs. Temperature ±20 ppm/°C *
Input Bias Current, Vin < 5 V peak-peak 100 µA *
Input Impedance
Small Signal, Vin < 5 V peak-peak 5 MΩ *
Large Signal, Vin > 5 V peak-peak 40 kΩ || 330 pF *
Power Off 40 kΩ || 330 pF *
Noise
Output, 100 kHz Bandwidth 0.7 mV peak-peak *
Output, 5 MHz Bandwidth 7 mV peak-peak *
Output Ripple 10 mV peak-peak @ (10% Fspan +F-full scale) *
Bandwidth, -3 dB 10 Hz 190 Hz
Output Step Response Time Refer to Model Table *
Common-Mode Voltage (CMV)
Input-to-Output, Continuous 1500 V rms, maximum *
Output-to-Power, Continuous3 ±3 V, maximum *
Transient ANSI/IEEE C37.90.1-1989 *
Common-Mode Rejection (CMR)
1 kΩ Source Imbalance, 50/60 Hz 120 dB *
Input Protection
Continuous 240 V rms, maximum *
Transient ANSI/IEEE C37.90.1-1989 *
Output Resistance 50 Ω *
Voltage Output Protection Continuous Short to Ground *
Output Selection Time 6 µs @ Cload = 0 to 2,000 pF *
Output Enable Control
Max Logic "0" +1.0 V *
Min Logic "1" +2.5 V *
Max Logic "1" +36 V *
Input Current "0" 0.4 mA *
Power Supply Voltage +5 V ±5% *
Power Supply Current 70 mA *
Power Supply Sensitivity, RTO ±0.005% of Span/% of Vs *
Mechanical Dimensions 2.275" x 2.375" x 0.595"
(57.8 mm x 59.1 mm x 15.1 mm)
*
Environmental
Temperature Range
   Rated Performance -40°C to +85°C *
   Operating Performance -40°C to +85°C *
   Storage -40°C to +85°C *
Relative Humidity 0 to 93% @ +40°C noncondensing *
RFI Susceptibility ±0.5% Span error @ 400 MHz, 5 Watt, 3 ft *
* Specifications same as model 5B45.
1 Jumper selectable. Refer to Field Connection diagram.
2 Includes the combined effects of repeatability, hysteresis, and nonlinearity. Loads heavier than 50 kΩ will degrade nonlinearity and gain temperature coefficient.
3 The Output Common must be kept within ±3 V of Power Common.
Specifications subject to change without notice.
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