74HC138屬于集成電路（IC）的信號(hào)開(kāi)關(guān)多路復(fù)用器解碼器。由安世半導(dǎo)體(中國(guó))有限公司制造生產(chǎn)的74HC138信號(hào)開(kāi)關(guān)，多路復(fù)用器，解碼器邏輯型信號(hào)開(kāi)關(guān)、多路復(fù)用器和編碼器 IC 可用于對(duì)以數(shù)字格式表示數(shù)據(jù)的電信號(hào)進(jìn)行路由和選擇。這些器件與設(shè)計(jì)用于模擬信號(hào)的類(lèi)似產(chǎn)品有所不同，它們保留的信息表示為兩個(gè)電狀態(tài)之一，而不是兩個(gè)外部界限內(nèi)的無(wú)窮變化量。

1. General description

The 74HC138; 74HCT138 decodes three binary weighted address inputs (A0, A1 and A2) to

eight mutually exclusive outputs (Y0 to Y7). The device features three enable inputs (E1, E2 and

E3). Every output will be HIGH unless E1 and E2 are LOW and E3 is HIGH. This multiple enable

function allows easy parallel expansion to a 1-of-32 (5 to 32 lines) decoder with just four '138 ICs

and one inverter. The '138 can be used as an eight output demultiplexer by using one of the active

LOW enable inputs as the data input and the remaining enable inputs as strobes. Inputs include

clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in

excess of VCC.

2. Features and benefits

? Wide supply voltage range from 2.0 to 6.0 V

? CMOS low power dissipation

? High noise immunity

? Latch-up performance exceeds 100 mA per JESD 78 Class II Level B

? Demultiplexing capability

? Multiple input enable for easy expansion

? Ideal for memory chip select decoding

? Active LOW mutually exclusive outputs

? Input levels:

? For 74HC138: CMOS level

? For 74HCT138: TTL level

? Complies with JEDEC standards:

? JESD8C (2.7 V to 3.6 V)

? JESD7A (2.0 V to 6.0 V)

? ESD protection:

? HBM JESD22-A114F exceeds 2000 V

? MM JESD22-A115-A exceeds 200 V

? Multiple package options

? Specified from -40 °C to +85 °C and from -40 °C to +125 °C