Overview
The SN74HC20NSR is a dual 4-input NAND gate integrated circuit produced by Texas Instruments. This device is part of the HC (High-Speed CMOS) logic family and is designed to perform the Boolean function Y = A ● B ● C ● D in positive logic for each of its two independent gates.
It is available in a 14-pin Small Outline Package (SOP) and is known for its wide operating voltage range of 2 V to 6 V and temperature range of –40°C to +85°C, making it versatile for various applications.
Key Specifications
| Parameter | Min | Nom | Max | Unit |
|---|---|---|---|---|
| Supply Voltage (VCC) | 2 | 5 | 6 | V |
| 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 |
| Output Voltage (VO) | 0 | - | VCC | V |
| Input Transition Time (tt) | 1000 (VCC=2V) | 500 (VCC=4.5V) | 400 (VCC=6V) | ns |
| Operating Free-Air Temperature (TA) | -40 | - | 85 | °C |
| Propagation Delay (tpd) | 45 (VCC=2V) | 9 (VCC=4.5V) | 8 (VCC=6V) | ns |
| Power Dissipation Capacitance per Gate (Cpd) | - | 25 | - | pF |
Key Features
- Buffered Inputs: Ensures stable input signals.
- Wide Operating Voltage Range: 2 V to 6 V, making it suitable for a variety of applications.
- Wide Operating Temperature Range: –40°C to +85°C, enhancing its reliability in different environments.
- Significant Power Reduction: Compared to LSTTL logic ICs, it offers lower power consumption.
- High Fanout Capability: Supports up to 10 LSTTL loads.
- Balanced CMOS Push-Pull Outputs: Allows the device to sink and source similar currents, ensuring balanced output performance.
Applications
- Alarm / Tamper Detect Circuit: Can be used to create circuits that detect tampering or alarm conditions.
- S-R Latch: The device can be configured to create an active-low SR latch, useful in memory and sequential logic circuits.
- System Control and Monitoring: Can drive tamper indicator LEDs and provide data to system controllers.
Q & A
- What is the primary function of the SN74HC20NSR?
The SN74HC20NSR contains two independent 4-input NAND gates, each performing the Boolean function Y = A ● B ● C ● D in positive logic.
- What is the operating voltage range of the SN74HC20NSR?
The operating voltage range is 2 V to 6 V.
- What is the operating temperature range of the SN74HC20NSR?
The operating temperature range is –40°C to +85°C.
- How many LSTTL loads can the SN74HC20NSR support?
It supports up to 10 LSTTL loads.
- What type of package is the SN74HC20NSR available in?
It is available in a 14-pin Small Outline Package (SOP).
- What are some typical applications of the SN74HC20NSR?
Typical applications include alarm/tamper detect circuits, S-R latches, and system control and monitoring.
- How does the SN74HC20NSR reduce power consumption compared to LSTTL logic ICs?
The SN74HC20NSR offers significant power reduction compared to LSTTL logic ICs due to its CMOS technology.
- What is the propagation delay of the SN74HC20NSR?
The propagation delay ranges from 45 ns (at VCC=2V) to 8 ns (at VCC=6V).
- How should unused inputs be handled in the SN74HC20NSR?
Unused inputs should be tied together or to VCC to ensure proper operation.
- What are the thermal characteristics of the SN74HC20NSR?
The device has specified thermal metrics such as junction-to-ambient thermal resistance (RθJA) and junction-to-case thermal resistance (RθJC), which vary depending on the package type.
