Fairchild Semiconductor 74ACT138SJX, 74ACT138SJ, 74ACT138SCX, 74ACT138SC, 74ACT138PC Datasheet

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November 1988

Revised August 2000

74AC138 • 74ACT138

1-of-8 Decoder/Demultiplexer

General Description

The AC/ACT138 is a high-speed 1-of-8 decoder/demultiplexer. This device is ideally suited for high-speed bipolar memory chip select address decoding. The multiple input enables allow parallel expansion to a 1-of-24 decoder using just three AC/ACT138 devices or a 1-of-32 decoder using four AC/ACT138 devices and one inverter.

Features

■ICC reduced by 50%

■Demultiplexing capability

■Multiple input enable for easy expansion

■Active LOW mutually exclusive outputs

■Outputs source/sink 24 mA

■ACT138 has TTL-compatible inputs

Ordering Code:

Order Number	Package Number	Package Description

74AC138SC	M16A	16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow

74AC138SJ	M16D	16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide

74AC138MTC	MTC16	16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

74AC138PC	N16E	16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

74ACT138SC	M16A	16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow

74ACT138SJ	M16D	16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide

74ACT138PC	N16E	16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

Device also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.

Connection Diagram

Logic Symbols

IEEE/IEC

Pin Descriptions

	Pin Names			Description

A0–A2				Address Inputs

E	1–E	2		Enable Inputs
E3				Enable Input
			7	Outputs
O	0–O

FACT is a trademark of Fairchild Semiconductor Corporation.

Decoder/Demultiplexer 8-of-1 74ACT138 • 74AC138

DS009925

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Fairchild Semiconductor 74ACT138SJX, 74ACT138SJ, 74ACT138SCX, 74ACT138SC, 74ACT138PC Datasheet

74AC138 • 74ACT138

Truth Table

Inputs

Outputs

H = HIGH Voltage Level

L = LOW Voltage Level

X = Immaterial

Functional Description

Logic Diagram

The AC/ACT138 high-speed 1-of-8 decoder/demultiplexer accepts three binary weighted inputs (A0, A1, A2) and, when enabled, provides eight mutually exclusive activeLOW outputs (O0–O7). The AC/ACT138 features three

Enable inputs, two active-LOW (E1, E2) and one active-

HIGH (E3). All outputs will be HIGH unless E1 and E2 are LOW and E3 is HIGH. This multiple enable function allows easy parallel expansion of the device to a 1-of-32 (5 lines to 32 lines) decoder with just four AC/ACT138 devices and one inverter (see Figure 1). The AC/ACT138 can be used as an 8-output demultiplexer by using one of the active LOW Enable inputs as the data input and the other Enable inputs as strobes. The Enable inputs which are not used must be permanently tied to their appropriate active-HIGH or active-LOW state.

Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.

FIGURE 1. Expansion to 1-of-32 Decoding

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Absolute Maximum Ratings(Note 1)

Supply Voltage (VCC)		− 0.5V to + 7.0V
DC Input Diode Current (IIK)
VI =	− 0.5V	− 20 mA
VI =	VCC + 0.5V	+ 20 mA
DC Input Voltage (VI)		− 0.5V to VCC + 0.5V
DC Output Diode Current (IOK)
VO =	− 0.5V	− 20 mA
VO =	VCC + 0.5V	+ 20 mA
DC Output Voltage (VO)		− 0.5V to VCC + 0.5V
DC Output Source
or Sink Current (IO)		± 50 mA
DC VCC or Ground Current
per Output Pin (ICC or IGND)		± 50 mA
Storage Temperature (TSTG)		− 65° C to + 150° C
Junction Temperature (TJ)
PDIP		140° C

Recommended Operating

Conditions

Supply Voltage (VCC)
AC	2.0V to 6.0V
ACT	4.5V to 5.5V
Input Voltage (VI)	0V to VCC
Output Voltage (VO)	0V to VCC
Operating Temperature (TA)	− 40° C to + 85° C
Minimum Input Edge Rate (∆ V/∆ t)
AC Devices
VIN from 30% to 70% of VCC
VCC @ 3.3V, 4.5V, 5.5V	125 mV/ns
Minimum Input Edge Rate (∆ V/∆ t)
ACT Devices
VIN from 0.8V to 2.0V
VCC @ 4.5V, 5.5V	125 mV/ns

Note 1: Absolute maximum ratings are those values beyond which damage to the device may occur. The databook specifications should be met, without exception, to ensure that the system design is reliable over its power supply, temperature, and output/input loading variables. Fairchild does not recommend operation of FACT circuits outside databook specifications.

DC Electrical Characteristics for AC

Symbol	Parameter	VCC	TA = + 25° C			TA = − 40° C to + 85° C	Units			Conditions
		(V)	Typ		Guaranteed Limits

VIH	Minimum HIGH Level	3.0	1.5	2.1		2.1		VOUT =		0.1V
	Input Voltage	4.5	2.25	3.15		3.15	V	or VCC −			0.1V
		5.5	2.75	3.85		3.85

VIL	Maximum LOW Level	3.0	1.5	0.9		0.9		VOUT =		0.1V
	Input Voltage	4.5	2.25	1.35		1.35	V	or VCC −			0.1V
		5.5	2.75	1.65		1.65

VOH	Minimum HIGH Level	3.0	2.99	2.9		2.9
	Output Voltage	4.5	4.49	4.4		4.4	V	IOUT =		−	50 µ A
		5.5	5.49	5.4		5.4

								VIN =	VIL or VIH
		3.0		2.56		2.46		IOH =	−	12 mA
		4.5		3.86		3.76	V	IOH =	−	24 mA
		5.5		4.86		4.76		IOH =	− 24 mA (Note 2)
VOL	Maximum LOW Level	3.0	0.002	0.1		0.1
	Output Voltage	4.5	0.001	0.1		0.1	V	IOUT =		50 µ A
		5.5	0.001	0.1		0.1

								VIN =	VIL or VIH
		3.0		0.36		0.44		IOL =	24 mA
		4.5		0.36		0.44	V	IOL =	24 mA 0
		5.5		0.36		0.44		IOL =	24 mA (Note 2)
IIN	Maximum Input	5.5		± 0.1		± 1.0	µ A	VI =	VCC, GND
(Note 4)	Leakage Current	5.5		± 0.1		± 1.0	µ A	VI =	VCC, GND
(Note 4)	Leakage Current

IOLD	Minimum Dynamic	5.5				75	mA	VOLD =		1.65V Max
IOHD	Output Current (Note 3)	5.5				− 75	mA	VOHD =			3.85V Min
ICC	Maximum Quiescent	5.5		4.0		40.0	µ A	VIN =	VCC or GND
(Note 4)	Supply Current	5.5		4.0		40.0	µ A	VIN =	VCC or GND
(Note 4)	Supply Current

Note 2: All outputs loaded; thresholds on input associated with output under test.

Note 3: Maximum test duration 2.0 ms, one output loaded at a time.

Note 4: IIN and ICC @ 3.0V are guaranteed to be less than or equal to the respective limit @ 5.5V VCC.

74ACT138 • 74AC138

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