Overview
The SN74HC148DR, produced by Texas Instruments, is an 8-line to 3-line priority encoder. This device is part of the HC148 series and is designed to encode eight data lines into a 3-line binary (octal) output. It features priority decoding, ensuring that only the highest-order data line is encoded. The SN74HC148DR includes input enable (EI) and output enable (EO) signals, which facilitate cascading multiple stages without the need for external circuitry. This makes it highly versatile for various digital logic applications.
Key Specifications
| Parameter | Condition | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| VCC Supply Voltage | 2 | 6 | V | ||
| VIH High-Level Input Voltage | VCC = 2V | 1.5 | V | ||
| VIH High-Level Input Voltage | VCC = 4.5V | 3.15 | V | ||
| VIH High-Level Input Voltage | VCC = 6V | 4.2 | V | ||
| VIL Low-Level Input Voltage | VCC = 2V | 0.5 | V | ||
| VIL Low-Level Input Voltage | VCC = 4.5V | 1.35 | V | ||
| VIL Low-Level Input Voltage | VCC = 6V | 1.8 | V | ||
| ICC Supply Current | VI = VCC or 0, IO = 0 | 80 | 160 | μA | |
| tpd Propagation Delay | 1-7 A0, A1, A2 @ VCC = 2V | 69 | 180 | ns | |
| tpd Propagation Delay | 1-7 A0, A1, A2 @ VCC = 4.5V | 23 | 54 | ns | |
| tpd Propagation Delay | 1-7 A0, A1, A2 @ VCC = 6V | 21 | 46 | ns | |
| TA Operating Free-Air Temperature | -40 | 85 | °C |
Key Features
- Wide operating voltage range of 2 V to 6 V
- Outputs can drive up to 10 LSTTL loads
- Low power consumption, 80-μA max ICC
- Typical propagation delay (tpd) = 16 ns
- ±4-mA output drive at 5 V
- Low input current of 1 μA max
- Encode eight data lines to 3-line binary (octal)
- Cascading circuitry with input enable (EI) and output enable (EO) signals for octal expansion without external circuitry
- Data inputs and outputs are active at the low logic level
Applications
- N-Bit encoding
- Code converters and generators
Q & A
- What is the primary function of the SN74HC148DR?
The primary function of the SN74HC148DR is to encode eight data lines into a 3-line binary (octal) output, with priority decoding ensuring that only the highest-order data line is encoded.
- What is the operating voltage range of the SN74HC148DR?
The operating voltage range of the SN74HC148DR is from 2 V to 6 V.
- How many LSTTL loads can the outputs of the SN74HC148DR drive?
The outputs of the SN74HC148DR can drive up to 10 LSTTL loads.
- What is the typical propagation delay of the SN74HC148DR?
The typical propagation delay (tpd) of the SN74HC148DR is 16 ns.
- What is the maximum output drive current at 5 V for the SN74HC148DR?
The maximum output drive current at 5 V for the SN74HC148DR is ±4 mA.
- How does the SN74HC148DR facilitate cascading multiple stages?
The SN74HC148DR facilitates cascading multiple stages through its input enable (EI) and output enable (EO) signals, allowing octal expansion without the need for external circuitry.
- What are the typical applications of the SN74HC148DR?
The typical applications of the SN74HC148DR include n-bit encoding and code converters and generators.
- What is the maximum supply current (ICC) of the SN74HC148DR?
The maximum supply current (ICC) of the SN74HC148DR is 160 μA.
- What is the operating free-air temperature range for the SN74HC148DR?
The operating free-air temperature range for the SN74HC148DR is from -40°C to 85°C.
- What is the input current of the SN74HC148DR when the input is at VCC or 0 V?
The input current of the SN74HC148DR when the input is at VCC or 0 V is ±0.1 nA to ±1000 nA.
- What is the input capacitance of the SN74HC148DR?
The input capacitance of the SN74HC148DR is 10 pF.
