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CD4013: Basic Guide on Pinout, Application Circuit

Introduction to the CD4013 Dual D Flip-Flop

The CD4013 is a dual D-type flip-flop integrated circuit that is part of the 4000 series CMOS logic family. It contains two independent D-type flip-flops in a single 14-pin package. D flip-flops are widely used in digital logic circuits for data storage, synchronization, frequency division, and many other applications.

Key Features of the CD4013

  • Dual D-type flip-flops in a 14-pin DIP or SOIC package
  • Wide operating voltage range: 3V to 15V
  • Low power consumption
  • High noise immunity
  • Buffered outputs for driving multiple loads
  • Set and reset inputs for each flip-flop
  • Toggle flip-flop operation possible

CD4013 Pinout and Pin Functions

The CD4013 comes in a 14-pin dual inline package (DIP) or a 14-pin small outline integrated circuit (SOIC) package. The pinout and pin functions are as follows:

Pin Number Pin Name Description
1 Q1 Flip-flop 1 output
2 ~Q1 Flip-flop 1 inverted output
3 CLOCK1 Flip-flop 1 clock input
4 RESET1 Flip-flop 1 asynchronous reset (active low)
5 DATA1 Flip-flop 1 data input
6 SET1 Flip-flop 1 asynchronous set (active low)
7 VSS Ground (0V)
8 SET2 Flip-flop 2 asynchronous set (active low)
9 DATA2 Flip-flop 2 data input
10 RESET2 Flip-flop 2 asynchronous reset (active low)
11 CLOCK2 Flip-flop 2 clock input
12 ~Q2 Flip-flop 2 inverted output
13 Q2 Flip-flop 2 output
14 VDD Positive supply voltage (3V to 15V)

Functional Description

The CD4013 contains two independent D-type flip-flops. Each flip-flop has the following inputs and outputs:

  • DATA (D): The data input. The state of this input is transferred to the output (Q) on the rising edge of the clock signal.
  • CLOCK: The clock input. The flip-flop output changes state on the rising edge of the clock signal when the data input is stable.
  • SET: Asynchronous set input (active low). When this input is pulled low, the output (Q) is forced high, regardless of the state of the other inputs.
  • RESET: Asynchronous reset input (active low). When this input is pulled low, the output (Q) is forced low, regardless of the state of the other inputs.
  • Q: The non-inverted output of the flip-flop.
  • ~Q: The inverted output of the flip-flop.

CD4013 Application Circuits

The CD4013 can be used in a wide variety of digital logic circuits. Some common applications include:

Frequency Division

D flip-flops can be used to divide the frequency of a clock signal by connecting the inverted output (~Q) back to the data input (D). This configuration is known as a “toggle” flip-flop, as the output changes state on every rising edge of the clock signal.

In this example, the input clock signal is divided by 2, resulting in an output signal with half the frequency of the input.

Data Synchronization

D flip-flops are often used to synchronize asynchronous input signals to a clock signal. This is done by connecting the asynchronous input signal to the data input (D) and using the clock signal to control when the data is latched into the flip-flop.

In this example, the asynchronous input signal is synchronized to the rising edge of the clock signal, ensuring that the output only changes state when the clock is high.

Shift Registers

Multiple D flip-flops can be cascaded to create a shift register, which is used to store and shift binary data. The output of each flip-flop is connected to the data input of the next flip-flop in the chain, and all flip-flops share a common clock signal.

In this example, a 4-bit shift register is created using two CD4013 ICs. Data is shifted through the register on each rising edge of the clock signal, and the output is available at the Q output of the last flip-flop in the chain.

Debouncing Switches

Mechanical switches often generate multiple, rapid transitions when pressed or released, which can cause problems in digital circuits. This phenomenon is known as “switch bounce”. D flip-flops can be used to debounce switches by latching the switch state on the rising edge of a clock signal.

In this example, the switch state is latched into the flip-flop on the rising edge of the clock signal. The flip-flop output remains stable even if the switch state changes multiple times during a single clock cycle.

CD4013 Timing Diagrams

To understand the operation of the CD4013 flip-flops, it is important to know how the inputs and outputs behave with respect to the clock signal. The following timing diagrams illustrate the operation of the CD4013 in various scenarios.

Data Latch Timing

This diagram shows how the output (Q) of the flip-flop changes state on the rising edge of the clock signal when the data input (D) is stable. The output remains unchanged if the data input changes state while the clock is high.

Set and Reset Timing

This diagram illustrates the behavior of the flip-flop when the set (S) or reset (R) inputs are activated. When either input is pulled low, the corresponding output (Q for set, ~Q for reset) is forced to the appropriate state, regardless of the state of the clock or data inputs. The flip-flop resumes normal operation when the set and reset inputs are both high.

CD4013 Electrical Characteristics

The CD4013 is a CMOS logic IC and has the following key electrical characteristics:

Parameter Symbol Min Typ Max Unit
Supply Voltage VDD 3 15 V
Input Voltage Low VIL -0.5 0.3VDD V
Input Voltage High VIH 0.7VDD VDD+0.5 V
Output Voltage Low (IOL = 1.6mA, VDD = 5V) VOL 0.05 V
Output Voltage High (IOH = -1.6mA, VDD = 5V) VOH 4.95 V
Quiescent Current (VDD = 5V) IDD 0.01 1 μA
Toggle Frequency (VDD = 5V) ft 4 MHz

These electrical characteristics are important to consider when designing circuits using the CD4013. The wide supply voltage range and low power consumption make the CD4013 suitable for battery-powered applications, while the high noise immunity and robust output drive make it a good choice for industrial and automotive environments.

CD4013 Layout and PCB Design Considerations

When designing a PCB layout for a circuit using the CD4013, there are several important considerations to keep in mind:

  1. Decoupling capacitors: Place 0.1μF ceramic capacitors as close as possible to the VDD and VSS pins of each CD4013 IC to decouple the power supply and reduce noise.

  2. Short, direct traces: Keep the traces connecting the inputs and outputs of the CD4013 as short and direct as possible to minimize Stray Capacitance and inductance, which can cause signal integrity issues at high frequencies.

  3. Ground plane: Use a solid ground plane on the PCB to provide a low-impedance return path for currents and to reduce noise coupling between signals.

  4. Adequate trace width: Ensure that the traces connecting to the CD4013 pins are wide enough to handle the expected current levels without excessive voltage drop or heating.

  5. Proper termination: If the CD4013 is driving long traces or cables, consider using proper termination techniques (e.g., series resistors) to minimize reflections and maintain signal integrity.

By following these guidelines, you can ensure that your CD4013-based circuits will perform reliably and meet your design requirements.

Frequently Asked Questions (FAQ)

  1. Q: What is the difference between the CD4013 and the 74HC74?
    A: The CD4013 is a CMOS logic IC, while the 74HC74 is a high-speed CMOS logic IC. The CD4013 has a wider supply voltage range (3V to 15V) and lower power consumption, while the 74HC74 has faster switching speeds and is compatible with TTL logic levels.

  2. Q: Can the CD4013 be used as a latch?
    A: Yes, the CD4013 can be used as a latch by connecting the SET and RESET inputs to the appropriate logic levels and using the CLOCK input to control when data is latched into the flip-flop.

  3. Q: How do I connect the unused inputs of the CD4013?
    A: If you are only using one of the two flip-flops in the CD4013, it is recommended to connect the unused inputs (SET, RESET, and CLOCK) to the appropriate logic levels to prevent them from floating and causing unwanted behavior. Connect unused SET and RESET inputs to VDD, and connect unused CLOCK inputs to either VDD or VSS.

  4. Q: What is the maximum toggle frequency of the CD4013?
    A: The maximum toggle frequency of the CD4013 is typically 4MHz when operated at a supply voltage of 5V. However, this can vary depending on factors such as load capacitance, supply voltage, and temperature.

  5. Q: Can the CD4013 be cascaded to create longer shift registers?
    A: Yes, multiple CD4013 ICs can be cascaded to create longer shift registers by connecting the Q output of each flip-flop to the DATA input of the next flip-flop in the chain. All flip-flops should share a common CLOCK signal.

Conclusion

The CD4013 dual D flip-flop is a versatile and widely-used CMOS logic IC that finds applications in a broad range of digital circuits, from simple data storage and synchronization to more complex frequency division and shift register designs. By understanding the pinout, functionality, and application circuits of the CD4013, you can effectively incorporate this device into your own projects and harness its capabilities to build reliable, efficient, and robust digital systems.