CD4026 (Decade Counter/Divider with 7-segment Display Driver)

The CD4026 is a Decade Counter/Divider with 7-segment Display Driver. It is part of the 4000 series of CMOS logic ICs, and it is commonly used in applications where you need to count events or divide frequency while driving a 7-segment display to show the result.

CD4026 IC Description:

The CD4026 is a decimal counter that counts from 0 to 9 and drives a 7-segment display directly for visual output. This IC contains a divide-by-10 counter and a 7-segment display driver on the same chip. It can be used in various applications like digital clocks, counters, and frequency dividers.

Key Features:

• Decade Counter: The CD4026 is a decade counter, meaning it counts in decimal from 0 to 9. After reaching 9, it resets back to 0 on the next clock pulse.
• 7-Segment Display Driver: The IC can drive a common-cathode 7-segment display directly to show the decimal digits 0 to 9.
• Low Power Consumption: Being based on CMOS technology, it has low power consumption compared to other logic families such as TTL.
• Counter Reset: The IC includes a reset pin (MR), which allows you to reset the counter back to 0 when required.
• Up/Down Counting: It can count up or down, depending on the state of the UP/DOWN control input.
• Clock Input: The IC counts on each rising edge of the clock signal, making it suitable for use in digital systems that require synchronized counting.
• Carry-Out (CO) Pin: The CO pin generates a pulse when the count reaches 9, which can be used to cascade multiple CD4026 ICs for higher counting ranges (e.g., for a two-digit counter).

Pin Configuration (16-pin package):

Functional Description:

1. Counter Operation:
   • The CD4026 counts from 0 to 9 on the rising edge of the clock input (CP).
   • When it reaches 9, the next clock pulse will reset the count to 0. The Q output (pin 14) will show the current count, and the 7-segment display outputs (Q to Qg) will display the corresponding digit.
2. 7-Segment Display Output:
   • The IC drives a 7-segment display directly, with seven outputs corresponding to the seven segments of the display.
   • The output pattern for the 7-segment display corresponds to the binary-coded decimal (BCD) value of the count. The segments will illuminate to form the digits 0 through 9.
3. Master Reset (MR):
   • The MR pin can be used to reset the counter to 0 immediately, regardless of the current count. When the MR pin is low, the IC resets, and the counter starts counting from 0.
4. Count Direction (Up/Down):
   • The Up/Down pin allows you to control whether the counter counts up or down.
     • If Up/Down is high, the counter will count up from 0 to 9.
     • If Up/Down is low, the counter will count down from 9 to 0.
5. Carry-Out (CO):
   • The CO pin produces a pulse when the counter reaches 9. This pulse can be used to cascade additional CD4026 ICs, allowing you to count to higher numbers (e.g., for a two-digit counter, the first IC counts the ones place, and the second counts the tens place).
6. Clock Input (CP):
   • The CP pin is where the clock signal is fed. On each rising edge of the clock, the counter increments or decrements based on the Up/Down pin state.

Truth Table:

Applications:

1. Digital Clocks:
   • The CD4026 can be used in the design of digital clocks where it counts time intervals and drives a 7-segment display for time indication.
2. Frequency Dividers:
   • It can be used as a frequency divider to divide the frequency of an input clock signal by 10.
3. Event Counting:
   • In applications like event counters or pulse counters, the CD4026 can count occurrences of an event and display the count on a 7-segment display.
4. Sequential Display Systems:
   • The CD4026 can be used in sequential display systems where multiple ICs are cascaded to display multi-digit numbers, such as in multi-digit counters.
5. Tachometers:
   • The CD4026 can be used in tachometers to count the number of rotations or cycles and display the result on a 7-segment display.
6. Counting Applications:
   • It is ideal for applications where you need to count items, events, or cycles and display the count, such as in lab experiments or testing devices.

Electrical Characteristics:

• Supply Voltage (Vcc): Typically 5V (Operating range is from 3V to 15V).
• Input Voltage (Vih/Vil): Logic levels for inputs; Vih (high-level input) is typically 2V, and Vil (low-level input) is typically 0.8V.
• Output Voltage (Vol/Voh): Logic levels for outputs; Vol (low-level output) is typically 0.1V (when sourcing 4mA), and Voh (high-level output) is typically Vcc – 0.2V (when sinking 2mA).
• Power Consumption: Low power, typical for CMOS technology.