The Harris Corporation CD4585BD is a high-performance 4-bit magnitude comparator designed for applications requiring precise comparison of binary or BCD (Binary-Coded Decimal) numbers. This device is widely utilized in digital systems where determining the relative magnitude of two 4-bit words is essential, such as in sorting algorithms, digital signal processing, and control systems.

## General Description

The CD4585BD is a CMOS (Complementary Metal-Oxide-Semiconductor) integrated circuit that compares two 4-bit binary or BCD words. It provides three output signals: A<B, A=B, and A>B, indicating whether the first input word (A) is less than, equal to, or greater than the second input word (B), respectively. The outputs are active high, meaning they output a logic high signal when the corresponding condition is true.

This comparator is designed to operate over a wide voltage range and is capable of handling high-speed comparisons with minimal power consumption. Its CMOS technology ensures low static power dissipation, making it suitable for battery-powered and energy-efficient applications.

## Electrical Specifications

* Supply Voltage (V\_DD): 3V to 18V
* Input Voltage (V\_in): 0V to V\_DD
* Output Voltage (V\_out): 0V to V\_DD
* Input Current (I\_in): Typically 100 nA at 18V, 25°C
* Output Current (I\_out): Typically 6.8 mA at V\_DD
* Quiescent Current (I\_q): Typically 100 µA at 18V
* Propagation Delay (t\_pd): Maximum 160 ns at V\_DD = 15V, C\_L = 50 pF
* Operating Temperature Range: -55°C to +125°C
* Package Type: 16-pin Dual In-line Package (DIP), 0.300" (7.62 mm) lead spacing

## Functional Features

* Bit Width: 4 bits
* Comparison Outputs: A<B, A=B, A>B (active high)
* Cascadable: Yes, for comparing wider bit-width words by connecting the outputs of multiple ICs
* Input Configuration: Eight inputs (A3 to A0 and B3 to B0) for the two 4-bit words
* Output Configuration: Three outputs corresponding to the comparison results
* Technology: CMOS for low power consumption and high noise immunity

## Applications

The CD4585BD is suitable for a variety of applications, including:

* Digital Systems: Used in microprocessor systems for arithmetic operations and decision-making processes.
* Control Systems: Employed in programmable logic controllers (PLCs) for process control and automation tasks.
* Signal Processing: Utilized in digital signal processors (DSPs) for comparing signal levels.
* Sorting Algorithms: Applied in sorting networks and algorithms where magnitude comparison is required.
* Measurement Systems: Used in digital voltmeters and other measurement instruments for comparing input signals.

## Design Considerations

When integrating the CD4585BD into a system design, consider the following:

* Power Supply Decoupling: Use appropriate decoupling capacitors close to the power supply pins to minimize noise and ensure stable operation.
* Input Signal Conditioning: Ensure that input signals are within the specified voltage range and are properly conditioned to avoid damage to the inputs.
* Output Loading: The outputs should be connected to appropriate logic inputs or buffers to handle the specified output current and prevent loading effects.
* PCB Layout: Careful PCB layout is essential to minimize noise and parasitic inductances, especially when operating at high speeds.

## Summary

The Harris Corporation CD4585BD is a versatile and efficient 4-bit magnitude comparator that offers high-speed performance, low power consumption, and a wide operating voltage range. Its CMOS technology and active high outputs make it suitable for a broad range of digital applications, from control systems to signal processing. By considering the design guidelines and integrating this comparator effectively, engineers can enhance the functionality and performance of their digital systems.