Overview
The SN74HC148NSR is an 8-line to 3-line priority encoder produced by Texas Instruments. This device is part of the 74HC series, known for its high-speed CMOS logic. The SN74HC148NSR features priority decoding, which ensures that only the highest-order data line is encoded. It is designed to encode eight data lines into a 3-line (4-2-1) binary (octal) output. The device includes input enable (EI) and output enable (EO) signals, allowing for easy cascading of multiple stages without the need for external circuitry.
Key Specifications
| Parameter | Min | 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 |
| ICC Supply Current | - | 80 | - | μA |
| tpd Propagation Delay | 16 (VCC=2V) | 36 (VCC=4.5V) | 46 (VCC=6V) | ns |
| IOH Output Current | -20 | -4 | -5.2 | mA |
| TA Operating Free-Air Temperature | -40 | - | 85 | °C |
Key Features
- Wide operating voltage range of 2V to 6V
- Outputs can drive up to 10 LSTTL loads
- Low power consumption, with a maximum ICC of 80 μA
- Typical propagation delay of 16 ns at VCC = 2V
- ±4-mA output drive at 5V
- Low input current of 1 μA max
- Encode eight data lines to 3-line binary (octal)
- Input enable (EI) and output enable (EO) signals for cascading
Applications
- N-Bit encoding
- Code converters and generators
- Prioritization in digital systems where multiple inputs need to be encoded into a smaller output set
- Cascading multiple encoders for larger input sets without external circuitry
Q & A
- What is the primary function of the SN74HC148NSR?
The primary function of the SN74HC148NSR is to encode eight data lines into a 3-line (4-2-1) binary (octal) output, with priority decoding to ensure only the highest-order data line is encoded.
- What is the operating voltage range of the SN74HC148NSR?
The operating voltage range is from 2V to 6V.
- How many LSTTL loads can the outputs of the SN74HC148NSR drive?
The outputs can drive up to 10 LSTTL loads.
- What is the typical propagation delay of the SN74HC148NSR at VCC = 2V?
The typical propagation delay is 16 ns at VCC = 2V.
- What are the input enable and output enable signals used for?
The input enable (EI) and output enable (EO) signals are used for cascading multiple stages without the need for external circuitry.
- What is the maximum supply current (ICC) of the SN74HC148NSR?
The maximum supply current (ICC) is 80 μA.
- What are some common applications of the SN74HC148NSR?
Common applications include N-Bit encoding, code converters and generators, and prioritization in digital systems.
- What is the operating temperature range of the SN74HC148NSR?
The operating temperature range is from -40°C to 85°C.
- How many data lines can the SN74HC148NSR encode?
The device can encode eight data lines into a 3-line binary output.
- What type of packages is the SN74HC148NSR available in?
The device is available in various packages including SOIC, PDIP, SO, and LCCC.
