Overview
The CD74HC390EX, produced by Harris Corporation (now part of Texas Instruments), is a high-speed CMOS logic dual decade counter. This integrated circuit is designed to provide flexible counting capabilities in various digital systems. It includes two independent 4-bit decade ripple counters, each with a divide-by-2 and a divide-by-5 section, allowing for configurations such as divide-by-2, 4, 5, 10, 20, 25, 50, and 100. The device is known for its balanced propagation delay, significant power reduction compared to LSTTL logic ICs, and high noise immunity.
Key Specifications
| Parameter | Value |
|---|---|
| Package Type | 16-DIP (0.300", 7.62mm), SOIC (16), PDIP (16) |
| Operating Voltage | 2V to 6V (HC types), 4.5V to 5.5V (HCT types) |
| Operating Temperature Range | -55°C to 125°C |
| Input Voltage Levels | VIH: 1.5V to 4.2V, VIL: 0.5V to 1.8V |
| Output Voltage Levels | VOH: 1.9V to 4.2V at IOH = –20 μA |
| Fanout | Standard outputs: 10 LSTTL loads, Bus driver outputs: 15 LSTTL loads |
| Propagation Delay | Balanced propagation delay and transition times |
Key Features
- Two independent 4-bit decade ripple counters with asynchronous clear inputs
- Flexible configuration: divide-by-2, 4, 5, 10, 20, 25, 50, 100
- High noise immunity: NIL = 30%, NIH = 30% of VCC at VCC = 5V
- Significant power reduction compared to LSTTL logic ICs
- Direct LSTTL input logic compatibility for HCT types
- CMOS input compatibility with low input current (II ≤ 1 μA)
Applications
The CD74HC390EX is suitable for a wide range of digital systems requiring counting functions. It is commonly used in:
- Digital counters and timers
- Frequency dividers
- Sequential logic circuits
- Automotive and industrial control systems
- Consumer electronics requiring precise counting and timing functions
Q & A
- What is the CD74HC390EX? The CD74HC390EX is a high-speed CMOS logic dual decade counter produced by Harris Corporation.
- What are the key features of the CD74HC390EX? It includes two independent 4-bit decade ripple counters, high noise immunity, and significant power reduction compared to LSTTL logic ICs.
- What are the operating voltage ranges for the CD74HC390EX? The operating voltage ranges are 2V to 6V for HC types and 4.5V to 5.5V for HCT types.
- What is the operating temperature range of the CD74HC390EX? The operating temperature range is -55°C to 125°C.
- What are the typical applications of the CD74HC390EX? It is used in digital counters, timers, frequency dividers, sequential logic circuits, and various control systems.
- How many LSTTL loads can the CD74HC390EX drive? It can drive up to 10 LSTTL loads for standard outputs and up to 15 LSTTL loads for bus driver outputs.
- Does the CD74HC390EX have asynchronous clear inputs? Yes, each counter has asynchronous clear inputs.
- What is the propagation delay characteristic of the CD74HC390EX? It has balanced propagation delay and transition times.
- Is the CD74HC390EX compatible with LSTTL input logic? Yes, the HCT types are compatible with LSTTL input logic.
- What is the input current characteristic of the CD74HC390EX? The input current is very low, with II ≤ 1 μA.
