Overview
The 74HCT221DB,118 is a dual non-retriggerable monostable multivibrator produced by NXP USA Inc. This integrated circuit is part of the 74HC/HCT logic family and is designed to provide high-speed CMOS functionality with compatibility to low power Schottky TTL (LSTTL) devices. The device features two independent monostable multivibrators, each capable of generating a single output pulse in response to an input trigger, without retriggering during the output pulse duration.
Key Specifications
| Parameter | Typical Value | Unit | Conditions |
|---|---|---|---|
| Supply Voltage (VCC) | 4.5 to 5.5 | V | |
| Operating Temperature | -40 to 125 | °C | |
| Propagation Delay (tPLH) nA, nB to nQ | 35 | ns | CL = 15 pF, VCC = 5 V, REXT = 5 kΩ, CEXT = 0 pF |
| Propagation Delay (tPHL) nA, nB to nQ | 29 | ns | CL = 15 pF, VCC = 5 V, REXT = 5 kΩ, CEXT = 0 pF |
| Input Capacitance (CI) | 3.5 | pF | |
| Power Dissipation Capacitance per Package (CPD) | 96 | pF | |
| Package Type | 16-SSOP |
Key Features
- Pulse Width Variance: Typically less than ±5%.
- Pin Compatibility: Pin-out identical to “123” and compatible with low power Schottky TTL (LSTTL) devices.
- Reset Functionality: Overriding reset terminates output pulse.
- Noise Immunity: nB inputs have hysteresis for improved noise immunity.
- Triggering: Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input pulse.
- Output Independence: Once triggered, the outputs (nQ, nQ) are independent of further transitions of nA and nB inputs.
- Timing Components: Output pulses are a function of the timing components.
Applications
- Digital Timing Circuits: Ideal for applications requiring precise timing and pulse generation.
- Signal Processing: Useful in signal processing circuits where single pulses need to be generated in response to input triggers.
- Automated Systems: Suitable for use in automated systems that require reliable and precise timing signals.
- Communication Systems: Can be used in communication systems for generating timing signals and pulses.
Q & A
- What is the 74HCT221DB,118 used for?
The 74HCT221DB,118 is used as a dual non-retriggerable monostable multivibrator, generating single output pulses in response to input triggers.
- What is the supply voltage range for the 74HCT221DB,118?
The supply voltage range is 4.5 to 5.5 volts.
- What is the operating temperature range for this IC?
The operating temperature range is -40°C to 125°C.
- How does the reset function work on the 74HCT221DB,118?
The overriding reset input (nRD) terminates the output pulse.
- What is the typical propagation delay for the 74HCT221DB,118?
The typical propagation delay (tPLH) is 35 ns for nA, nB to nQ, and 29 ns for tPHL under specified conditions.
- Is the 74HCT221DB,118 compatible with TTL devices?
Yes, it is compatible with low power Schottky TTL (LSTTL) devices.
- What type of package does the 74HCT221DB,118 come in?
The IC comes in a 16-SSOP package.
- How does the input triggering work on the 74HCT221DB,118?
Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input pulse.
- What is the significance of the nB inputs having hysteresis?
The nB inputs having hysteresis improves noise immunity.
- Can the output pulses be terminated by an external signal?
Yes, the output pulses can be terminated by the overriding active LOW reset inputs (nRD).
