Overview
The 74HC138DTR2G is a high-performance silicon-gate CMOS 1-of-8 decoder/demultiplexer produced by ON Semiconductor. This device is identical in pinout to the LS138 and is designed to decode a three-bit binary weighted address to one of eight active-low outputs. It features three chip select inputs, two active-low (E1 and E2) and one active-high (E3), which facilitate demultiplexing, cascading, and chip-selecting functions. The device is compatible with standard CMOS outputs and, with pullup resistors, can also interface with LSTTL outputs.
Key Specifications
| Parameter | Min | Max | Unit |
|---|---|---|---|
| VCC (DC Supply Voltage) | 2.0 | 6.0 | V |
| VIN, VOUT (DC Input, Output Voltage) | 0 | VCC | V |
| TA (Operating Free-Air Temperature) | -55 | 125 | °C |
| tr, tf (Input Rise or Fall Time) | 0 | 1000 (VCC=2.0V), 500 (VCC=4.5V), 400 (VCC=6.0V) | ns |
| VIH (Minimum High-Level Input Voltage) | 1.5 (VCC=2.0V), 3.15 (VCC=4.5V), 4.2 (VCC=6.0V) | V | |
| VIL (Maximum Low-Level Input Voltage) | 0.8 (VCC=2.0V), 2.1 (VCC=4.5V), 2.8 (VCC=6.0V) | V | |
| IOH (High-Level Output Voltage) | 1.9 (VCC=2.0V), 4.4 (VCC=4.5V), 5.9 (VCC=6.0V) | V | |
| tPLH, tPHL (Maximum Propagation Delay) | 23 (VCC=6.0V), 27 (VCC=4.5V), 135 (VCC=2.0V) | ns |
Key Features
- Wide Supply Voltage Range from 2.0V to 6.0V.
- Output Drive Capability: 10 LSTTL Loads.
- Outputs Directly Interface to CMOS, NMOS, and TTL.
- Low Input Current: 1.0 µA.
- High Noise Immunity Characteristic of CMOS Devices.
- Schmitt Trigger Action at All Inputs.
- ESD Protection Tested per JESD 22.
- Totally Lead-Free & Fully RoHS Compliant.
- Halogen and Antimony Free. “Green” Device.
Applications
- Memory chip select decoding.
- Demultiplexing.
- Single line peripheral control.
- Cascading and chip-selecting functions.
Q & A
- What is the operating voltage range of the 74HC138DTR2G?
The operating voltage range is from 2.0V to 6.0V.
- How many outputs does the 74HC138DTR2G have?
The device has eight active-low outputs.
- What are the types of chip select inputs on the 74HC138DTR2G?
There are two active-low (E1 and E2) and one active-high (E3) chip select inputs.
- Is the 74HC138DTR2G compatible with LSTTL outputs?
Yes, with pullup resistors, the inputs are compatible with LSTTL outputs.
- What is the maximum propagation delay of the 74HC138DTR2G?
The maximum propagation delay varies by voltage but is typically around 23-135 ns depending on the supply voltage.
- Does the 74HC138DTR2G have ESD protection?
Yes, it exceeds 200-V Machine Model, 2000-V Human Body Model, and 1000-V Charged Device Model).
- Is the 74HC138DTR2G RoHS compliant?
Yes, it is totally lead-free and fully RoHS compliant).
- What are some common applications of the 74HC138DTR2G?
Common applications include memory chip select decoding, demultiplexing, and single line peripheral control).
- How many address inputs does the 74HC138DTR2G have?
The device has three address inputs (A0, A1, A2)).
- What is the power dissipation capacitance of the 74HC138DTR2G?
The power dissipation capacitance is typically around 55 pF at 25°C and VCC = 5.0V).
