Overview
The SN74HC74DT, produced by Texas Instruments, is a dual D-type positive-edge-triggered flip-flop integrated circuit. This device contains two independent flip-flops, each with asynchronous preset and clear pins. It operates within a wide voltage range of 2 V to 6 V and is designed for use in a variety of digital logic applications. The SN74HC74DT is part of the 74HC series, known for its low power consumption and high performance.
Key Specifications
| Parameter | Min | Nom | Max | Unit |
|---|---|---|---|---|
| Supply Voltage (VCC) | 2 | 5 | 6 | V |
| Operating Temperature (TA) | -40 | 85 | °C | |
| High-Level Input Voltage (VIH) | 1.5 (VCC=2V) | 3.15 (VCC=4.5V) | 4.2 (VCC=6V) | V |
| Low-Level Input Voltage (VIL) | 0.5 (VCC=2V) | 1.35 (VCC=4.5V) | 1.8 (VCC=6V) | V |
| Clock Frequency (fclock) | 6 (VCC=2V) | 31 (VCC=4.5V) | 36 (VCC=6V) | MHz |
| Propagation Delay (tpd) | 70 (VCC=2V) | 20 (VCC=4.5V) | 15 (VCC=6V) | ns |
| Transition Time (tt) | 28 (VCC=2V) | 8 (VCC=4.5V) | 6 (VCC=6V) | ns |
Key Features
- Buffered inputs
- Wide operating voltage range: 2 V to 6 V
- Wide operating temperature range: -40°C to +85°C
- Supports fanout up to 10 LSTTL loads
- Significant power reduction compared to LSTTL logic ICs
- Low power consumption, 40-µA max ICC
- Typical propagation delay of 15 ns
- ±4-mA output drive at 5 V
- Low input current of 1 µA max
- Balanced CMOS push-pull outputs
- Clamp diode structure for input and output protection
Applications
- Convert a momentary switch to a toggle switch
- Divide a clock signal by 2 or 4
- General-purpose digital logic circuits
- Counters and shift registers
- Memory elements in digital systems
Q & A
- What is the operating voltage range of the SN74HC74DT?
The operating voltage range is 2 V to 6 V.
- What is the maximum clock frequency for the SN74HC74DT at 6 V supply voltage?
The maximum clock frequency is 36 MHz.
- How many LSTTL loads can the SN74HC74DT drive?
The device can drive up to 10 LSTTL loads.
- What is the typical propagation delay of the SN74HC74DT?
The typical propagation delay is 15 ns.
- What are the asynchronous control inputs for the flip-flops?
The asynchronous control inputs are preset (PRE) and clear (CLR).
- What is the purpose of the clamp diode structure in the SN74HC74DT?
The clamp diode structure provides input and output protection against voltage spikes.
- How should the outputs of the SN74HC74DT be handled if they are not used?
Unused outputs can be left floating but should not be connected directly to VCC or ground.
- What are the key timing considerations for the SN74HC74DT?
The key timing considerations include maximum clock frequency, pulse duration, setup time, and hold time.
- What is the recommended capacitive load at the output for optimal performance?
The recommended capacitive load is ≤ 70 pF.
- How should the resistive load at the output be managed?
The resistive load should be larger than (VCC / IO(max)) Ω to ensure the maximum output current is not violated.
