Overview
The SN74HC148DE4 is an 8-line to 3-line priority encoder produced by Texas Instruments. This device is part of the HC148 series, which features priority decoding of the inputs to ensure that only the highest-order data line is encoded. The SN74HC148DE4 encodes eight data lines into a 3-line binary (octal) output, making it suitable for various digital logic applications.
The device includes input enable (EI) and output enable (EO) signals, allowing for the cascading of multiple stages without the need for additional external circuitry. This functionality enhances its usability in complex digital systems.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC Supply Voltage | 2 | 5 | 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 |
| VOH High-Level Output Voltage (IOH = -20 μA, VCC = 2V) | 1.9 | - | - | V |
| VOH High-Level Output Voltage (IOH = -20 μA, VCC = 4.5V) | 4.4 | - | - | V |
| VOH High-Level Output Voltage (IOH = -20 μA, VCC = 6V) | 5.9 | - | - | V |
| VOL Low-Level Output Voltage (IOL = 20 μA, VCC = 2V) | 0.002 | - | - | V |
| VOL Low-Level Output Voltage (IOL = 20 μA, VCC = 4.5V) | 0.001 | - | - | V |
| VOL Low-Level Output Voltage (IOL = 20 μA, VCC = 6V) | 0.001 | - | - | V |
| tpd Propagation Delay (VCC = 2V) | 69 | - | 180 | ns |
| tpd Propagation Delay (VCC = 4.5V) | 23 | - | 54 | ns |
| tpd Propagation Delay (VCC = 6V) | 21 | - | 46 | ns |
| TJ Junction Temperature | - | - | 150 | °C |
| Tstg Storage Temperature | -65 | - | 150 | °C |
Key Features
- Wide operating voltage range of 2V to 6V
- 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 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 multiple stages without external circuitry
Applications
- N-Bit encoding
- Code converters and generators
- Priority decoding in digital logic systems
- Cascaded encoding for complex digital circuits
Q & A
- What is the primary function of the SN74HC148DE4?
The SN74HC148DE4 is an 8-line to 3-line priority encoder, encoding eight data lines into a 3-line binary (octal) output.
- What is the operating voltage range of the SN74HC148DE4?
The operating voltage range is from 2V to 6V.
- How many LSTTL loads can the outputs of the SN74HC148DE4 drive?
The outputs can drive up to 10 LSTTL loads.
- What is the typical propagation delay of the SN74HC148DE4?
The typical propagation delay (tpd) is 16 ns.
- What is the maximum output drive current at 5V for the SN74HC148DE4?
The maximum output drive current at 5V is ±4 mA.
- How does the SN74HC148DE4 handle cascading multiple stages?
The device includes input enable (EI) and output enable (EO) signals, allowing for cascading multiple stages without additional external circuitry.
- What are some common applications of the SN74HC148DE4?
Common applications include n-bit encoding, code converters, and generators, as well as priority decoding in digital logic systems.
- What is the maximum junction temperature for the SN74HC148DE4?
The maximum junction temperature is 150°C.
- What is the storage temperature range for the SN74HC148DE4?
The storage temperature range is from -65°C to 150°C.
- How much power does the SN74HC148DE4 consume?
The device has a low power consumption, with a maximum ICC of 80 μA.
- What is the maximum input current for the SN74HC148DE4?
The maximum input current is 1 μA.
