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74HCT138D

3-to-8 decoder/demux, TTL inputs, active-LOW outputs, SOIC-16

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Pieza del fabricante：

74HCT138D

Paquete：

SOIC-16 / SOT109-1 (9.9×3.9×1.45 mm, 1.27mm pitch)

Descripción

Productos

The 74HCT138D from Nexperia is a 3-to-8 line decoder/demultiplexer with TTL-compatible input levels in an SOIC-16 package. It decodes three binary-weighted address inputs (A0-A2) to eight mutually exclusive active-LOW outputs (Y0-Y7). Three enable inputs (E1, E2 active-LOW; E3 active-HIGH) allow easy parallel expansion to 1-of-32 decoding with just four ICs and one inverter.

Especificaciones

Logic Function	3-to-8 line decoder/demultiplexer (inverting outputs)
Tensión de alimentación	4.5V to 5.5V (HCT)
Retardo de propagación	19 ns typical @ 5V
Output Drive	±4 mA
Address Inputs	3 (A0, A1, A2)
Outputs	8 (Y0-Y7, active-LOW, mutually exclusive)
Enable Inputs	E1, E2 (active-LOW), E3 (active-HIGH)
Input Levels	TTL (74HCT138)
Temperatura de funcionamiento	-40°C to +125°C
Paquete	SOIC-16 (SOT109-1, 9.9×3.9 mm)

Características

Decodes 3 binary inputs to 8 mutually exclusive active-LOW outputs
Three enable inputs for easy cascading and expansion
Expandable to 1-of-32 decoder with four ‘138 ICs + one inverter
Can serve as 1-to-8 demultiplexer using enable as data input
Ideal for memory chip-select decoding
TTL-compatible input levels
Input clamp diodes for overvoltage interface

Aplicaciones

Memory chip-select decoding in microprocessor systems
I/O port address decoding
Data demultiplexing and distribution
1-of-N decoder expansion in digital systems

Introducción del producto:74HCT138D Presentación del producto

The 74HCT138D from Nexperia is a 3-to-8 line decoder/demultiplexer with TTL-compatible inputs in an SOIC-16 package. Decoding three address inputs to eight active-LOW mutually exclusive outputs, with three enable inputs for cascading expansion to 1-of-32 decoding. Ideal for memory chip-select decoding, I/O port addressing, and data demultiplexing in 5V microprocessor systems.

Principio de funcionamiento:74HCT138D Principio de funcionamiento

The 74HCT138D decodes three binary-weighted address inputs (A0, A1, A2) to activate one of eight active-LOW outputs (Y0-Y7). The selected output goes LOW while all others remain HIGH. Three enable inputs control the device: E1 and E2 are active-LOW, E3 is active-HIGH. The device is enabled only when E1=LOW, E2=LOW, and E3=HIGH. This triple-enable scheme enables easy cascading; for example, four 74HCT138Ds with a single inverter can create a 5-to-32 line decoder (1-of-32). The device can also function as a 1-to-8 demultiplexer by using one active-LOW enable as a data input and the remaining enables as strobes, routing data to the selected output. The TTL-compatible input stage accepts standard 5V logic levels directly.

Descripción de la clavija:74HCT138D Definición y funciones de las clavijas

Pin	Nombre	Tipo	Función
1	A0	Entrada	Address input LSB (TTL level)
2	A1	Entrada	Address input
3	A2	Entrada	Address input MSB
4	E1	Entrada	Enable input (active LOW)
5	E2	Entrada	Enable input (active LOW)
6	E3	Entrada	Enable input (active HIGH)
7	Y7	Salida	Decoded output (active LOW)
8	GND	Potencia	Tierra (0V)
9	Y6	Salida	Decoded output
10	Y5	Salida	Decoded output
11	Y4	Salida	Decoded output
12	Y3	Salida	Decoded output
13	Y2	Salida	Decoded output
14	Y1	Salida	Decoded output
15	Y0	Salida	Decoded output
16	VCC	Potencia	Supply voltage (4.5-5.5V)

Application Scenarios:In which products and applications is74HCT138D usado

Memory chip-select decoding in 5V microprocessor systems
I/O port address decoding and peripheral selection
Data demultiplexing: routing serial data to one of eight outputs
1-of-32 decoder expansion using four 74HCT138Ds

Alternative Models:What chips are recommended as replacements for 74HCT138D

Fabricante	Número de pieza	Paquete	Notas
Nexperia	74HC138D	SOIC-16	CMOS input levels (2.0-6.0V)
TI	SN74HCT138DR	SOIC-16	Functionally equivalent
ON Semi	MC74HCT138ADR2G	SOIC-16	Functionally equivalent
Nexperia	74HCT138PW	TSSOP-16	Smaller footprint
Nexperia	74HC238D	SOIC-16	Active-HIGH output version