MM74C85N

Product Overview

• Category: Integrated Circuit
• Use: BCD-to-Seven Segment Decoder/Driver
• Characteristics: High-speed, low-power consumption, compact size
• Package: DIP (Dual In-line Package)
• Essence: Converts binary-coded decimal (BCD) input into a 7-segment display output
• Packaging/Quantity: Available in tubes of 25 units

Specifications

• Supply Voltage: 5V
• Input Current: 1.5mA (max)
• Output Current: 5mA (max)
• Operating Temperature Range: -40°C to +85°C
• Propagation Delay Time: 35ns (typical)

Detailed Pin Configuration

The MM74C85N has a total of 16 pins, which are assigned as follows:

1. A0 - BCD Input A0
2. A1 - BCD Input A1
3. A2 - BCD Input A2
4. A3 - BCD Input A3
5. LT - Lamp Test Input
6. BI/RBO - Blanking Input/ Ripple Blanking Output
7. RBI - Ripple Blanking Input
8. GND - Ground
9. F - Seven Segment Output F
10. E - Seven Segment Output E
11. D - Seven Segment Output D
12. C - Seven Segment Output C
13. B - Seven Segment Output B
14. A - Seven Segment Output A
15. VCC - Positive Power Supply
16. RBO - Ripple Blanking Output

Functional Features

The MM74C85N is designed to decode and drive a common-cathode 7-segment LED display. It accepts a 4-bit binary-coded decimal (BCD) input and generates the corresponding outputs to display the decimal digits 0-9. The lamp test input (LT) allows all segments to be turned on simultaneously for testing purposes. The blanking input (BI) and ripple blanking input (RBI) control the display's blanking and ripple blanking functions, respectively.

Advantages and Disadvantages

Advantages: - High-speed operation enables real-time display updates - Low-power consumption makes it suitable for battery-powered devices - Compact size saves board space in electronic designs

Disadvantages: - Limited to driving common-cathode 7-segment displays only - Requires additional components for multiplexing multiple displays

Working Principles

The MM74C85N uses a combination of logic gates and internal decoding circuits to convert the BCD input into the appropriate signals for driving the 7-segment display. Each segment of the display is controlled by a separate output pin, which can be individually activated or deactivated based on the input value. The inputs are decoded internally to determine the correct combination of outputs required to display the corresponding digit.

Detailed Application Field Plans

The MM74C85N is commonly used in various applications that require the conversion of BCD data into a 7-segment display output. Some typical application fields include:

1. Digital Clocks: The MM74C85N can be used to drive the 7-segment display in digital clocks, allowing the display of hours, minutes, and seconds.
2. Counters: It can be employed in counter circuits to display the count value in decimal format.
3. Measurement Instruments: The IC can be utilized in measurement instruments such as multimeters or voltmeters to display the measured values accurately.
4. Industrial Control Systems: The MM74C85N finds applications in industrial control systems where numerical data needs to be displayed.

Detailed and Complete Alternative Models

Some alternative models that serve similar functions to the MM74C85N are:

1. CD4511: BCD-to-7 Segment Latch/Decoder/Driver
2. SN74LS47: BCD-to-7 Segment Decoder/Driver with Open-Collector Outputs
3. HEF4543B: BCD-to-7 Segment Latch/Decoder/Driver with Constant Current Source Outputs

These alternative models offer similar functionality and can be used as replacements for the MM74C85N in various applications.

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