Overview
The CD74HC221E is a High-Speed CMOS Logic Dual Monostable Multivibrator with Reset, produced by Texas Instruments. This device is part of the HC series, known for its high-speed CMOS logic and wide operating voltage range. The CD74HC221E is designed to generate a single pulse of a specified width in response to a trigger signal, making it versatile for various timing and pulse generation applications.
The device features two independent monostable multivibrators, each capable of being triggered by either a rising or falling edge of the input signal. The output pulse width can be adjusted using external resistor (RX) and capacitor (CX) components, providing a wide range of pulse widths. The device also includes a reset input to terminate the output pulse prematurely.
Key Specifications
| Parameter | Symbol | Test Conditions | Min | Max | Units | |
|---|---|---|---|---|---|---|
| DC Supply Voltage | VCC | - | -0.5 | - | 7 | V |
| High Level Input Voltage | VIH | VCC = 4.5V | 3.15 | - | 6 | V |
| Low Level Input Voltage | VIL | VCC = 4.5V | - | - | 1.35 | V |
| High Level Output Voltage | VOH | VCC = 4.5V, IO = -4mA | 4.2 | - | - | V |
| Propagation Delay, Trigger A, B, R to Q | tPLH | VCC = 4.5V, CL = 50pF | 42 | - | 53 | ns |
| Input Pulse Width A | tWL | VCC = 4.5V | 14 | - | 18 | ns |
| Input Pulse Width B | tWH | VCC = 4.5V | 14 | - | 18 | ns |
| Operating Temperature Range | - | -55 to 125 | - | - | - | °C |
Key Features
- Dual monostable multivibrators with reset, allowing for independent operation of each multivibrator.
- External resistor (RX) and capacitor (CX) control the timing and accuracy of the output pulse width.
- Pulse triggering on the B input occurs at a specific voltage level, independent of the rise and fall time of the trigger pulse.
- Leading-edge-triggering (B) and trailing-edge-triggering (A) inputs are provided.
- Reset input (R) to terminate the output pulse prematurely.
- Wide operating voltage range: 2 V to 6 V.
- Wide operating temperature range: -55°C to +125°C.
- Low power consumption.
- High-speed CMOS logic.
Applications
- Timing and pulse generation circuits.
- Alarm and tamper detect circuits.
- Pulse stretching and conditioning.
- Frequency division and counting circuits.
- Sequential logic circuits.
- Automotive and industrial control systems.
Q & A
- What is the CD74HC221E?
The CD74HC221E is a High-Speed CMOS Logic Dual Monostable Multivibrator with Reset, used for generating single pulses of specified widths in response to trigger signals.
- What is the operating voltage range of the CD74HC221E?
The operating voltage range is from 2 V to 6 V.
- How is the output pulse width controlled?
The output pulse width is controlled by an external resistor (RX) and capacitor (CX).
- What are the triggering options for the CD74HC221E?
The device can be triggered by either a rising or falling edge of the input signal.
- Can the output pulse be terminated prematurely?
Yes, the output pulse can be terminated by a LOW level on the Reset (R) pin.
- What is the temperature range for the CD74HC221E?
The operating temperature range is from -55°C to +125°C.
- What types of packages are available for the CD74HC221E?
The device is available in PDIP, SOIC, SOP, and TSSOP packages.
- Is the CD74HC221E RoHS compliant?
Yes, the CD74HC221E is RoHS compliant.
- What are some common applications for the CD74HC221E?
Common applications include timing and pulse generation circuits, alarm and tamper detect circuits, and sequential logic circuits.
- How do I calculate the pulse width of the CD74HC221E?
The pulse width can be calculated using the formula: tW = 0.7 * RX * CX at VCC = 4.5V.
- What are the propagation delays for the CD74HC221E?
The propagation delays (tPLH and tPHL) vary depending on the supply voltage and load capacitance, but typically range from 42 ns to 53 ns for VCC = 4.5V and CL = 50pF.
