Overview
The SN74HC27DR is a triple 3-input NOR gate integrated circuit produced by Texas Instruments. This device is part of the HC series, known for its high-speed CMOS logic. It contains three independent 3-input NOR gates, each performing the Boolean function Y = A + B + C in positive logic. The SN74HC27DR is available in a 14-pin SOIC package, making it suitable for a variety of digital logic applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC (Supply Voltage) | 2 | 5 | 6 | V |
| VIH (High-level Input Voltage) | 1.5 (VCC=2V) | 3.15 (VCC=4.5V) | 4.2 (VCC=6V) | V |
| VIL (Low-level Input Voltage) | 0.5 (VCC=2V) | 1.35 (VCC=4.5V) | 1.8 (VCC=6V) | V |
| TA (Operating Free-Air Temperature) | -40 | - | 85 | °C |
| tpd (Propagation Delay) | 35 (VCC=2V) | 10 (VCC=4.5V) | 9 (VCC=6V) | ns |
| tt (Transition Time) | 27 (VCC=2V) | 7 (VCC=4.5V) | 6 (VCC=6V) | ns |
| RθJA (Junction-to-Ambient Thermal Resistance) | - | - | 133.6 | °C/W |
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
- Balanced CMOS push-pull outputs
- Low power consumption
Applications
- Alarm / tamper detect circuits
- S-R latch circuits
- General digital logic circuits requiring 3-input NOR gates
Q & A
- What is the function of the SN74HC27DR?
The SN74HC27DR contains three independent 3-input NOR gates, each performing the Boolean function Y = A + B + C in positive logic.
- What is the operating voltage range of the SN74HC27DR?
The operating voltage range is from 2 V to 6 V.
- What is the operating temperature range of the SN74HC27DR?
The operating temperature range is from -40°C to +85°C.
- How many LSTTL loads can the SN74HC27DR drive?
The device can drive up to 10 LSTTL loads.
- What is the typical propagation delay of the SN74HC27DR?
The typical propagation delay is 10 ns at VCC = 4.5 V.
- What type of outputs does the SN74HC27DR have?
The device has balanced CMOS push-pull outputs.
- How should unused inputs be handled?
Unused inputs must be terminated to either VCC or ground, either directly or with a pull-up or pull-down resistor.
- What is the recommended capacitive load for the outputs?
The capacitive load should be ≤ 70 pF for optimal performance.
- What are some common applications of the SN74HC27DR?
Common applications include alarm/tamper detect circuits and S-R latch circuits.
- What package type is the SN74HC27DR available in?
The SN74HC27DR is available in a 14-pin SOIC package.
- What is the junction-to-ambient thermal resistance of the SN74HC27DR in SOIC package?
The junction-to-ambient thermal resistance is 133.6 °C/W.
