Overview
The SN74LVC138A, specifically the SN74LVC138ADRG4, is a 3-line to 8-line decoder or demultiplexer designed by Texas Instruments. This device is optimized for high-performance memory-decoding or data-routing applications that require very short propagation delay times. It operates within a voltage range of 1.65 V to 3.6 V, making it versatile for various system designs. The decoder selects one of eight output lines based on the conditions at the binary-select inputs (A0, A1, A2) and the three enable inputs (G2, G0, G1), reducing the need for external gates or inverters in many applications.
Key Specifications
| Parameter | Unit | Min | Typ | Max |
|---|---|---|---|---|
| VCC (Supply Voltage) | V | 2 | 5.5 | |
| VIH (High-Level Input Voltage) | V | VCC × 0.7 | ||
| VIL (Low-Level Input Voltage) | V | VCC × 0.3 | ||
| tpd (Propagation Delay Time) at 3.3 V | ns | 8.1 | 11.4 | 13.5 |
| VOH (High-Level Output Voltage) at IOH = –50 μA | V | VCC – 0.1 | ||
| VOL (Low-Level Output Voltage) at IOL = 50 μA | V | 0.1 | ||
| ICC (Supply Current) | μA | 20 | ||
| Ioff (Input/Output Power-Off Leakage Current) | μA | 5 | ||
| Ci (Input Capacitance) | pF | 2.1 |
Key Features
- Operates from 1.65 V to 3.6 V, with inputs accepting voltages up to 5.5 V.
- Maximum propagation delay time of 5.8 ns at 3.3 V.
- Typical output ground bounce (VOLP) less than 0.8 V at VCC = 3.3 V, TA = 25°C.
- Typical output VOH undershoot (VOHV) greater than 2 V at VCC = 3.3 V, TA = 25°C.
- Latch-up performance exceeds 250 mA per JESD 17.
- Supports mixed-mode voltage operation on all ports.
- Ioff supports partial-power-down mode operation.
- Standard CMOS inputs with high impedance.
Applications
- Output expansion.
- LED matrix control.
- 7-segment display control.
- 8-bit data storage.
- High-performance memory-decoding or data-routing applications.
Q & A
- What is the operating voltage range of the SN74LVC138A?
The SN74LVC138A operates from 1.65 V to 3.6 V.
- What is the maximum propagation delay time at 3.3 V?
The maximum propagation delay time at 3.3 V is 11.4 ns.
- What is the typical output ground bounce at 3.3 V?
The typical output ground bounce (VOLP) is less than 0.8 V at VCC = 3.3 V, TA = 25°C.
- Does the SN74LVC138A support partial-power-down mode?
Yes, it supports partial-power-down mode operation through Ioff.
- What are the types of enable inputs on the SN74LVC138A?
The device has two active-low (G0, G1) and one active-high (G2) enable inputs.
- What is the latch-up performance of the SN74LVC138A?
The latch-up performance exceeds 250 mA per JESD 17.
- Can the SN74LVC138A be used in high-performance memory systems?
Yes, it is designed for high-performance memory-decoding or data-routing applications.
- What is the input capacitance of the SN74LVC138A?
The input capacitance is typically 2.1 pF.
- How many output lines does the SN74LVC138A select?
The device selects one of eight output lines based on the input conditions.
- What are some common applications of the SN74LVC138A?
Common applications include output expansion, LED matrix control, 7-segment display control, and 8-bit data storage.
