NSC DM54LS139J-883, DM54LS139E-883 Datasheet

June 1989

54LS138/DM54LS138/DM74LS138,

54LS139/DM54LS139/DM74LS139

Decoders/Demultiplexers

General Description

These Schottky-clamped circuits are designed to be used in high-performance memory-decoding or data-routing applications, requiring very short propagation delay times. In high-performance memory systems these decoders can be used to minimize the effects of system decoding. When used with high-speed memories, the delay times of these decoders are usually less than the typical access time of the memory. This means that the effective system delay introduced by the decoder is negligible.

The LS138 decodes one-of-eight lines, based upon the conditions at the three binary select inputs and the three enable inputs. Two active-low and one active-high enable inputs reduce the need for external gates or inverters when expanding. A 24-line decoder can be implemented with no external inverters, and a 32-line decoder requires only one inverter. An enable input can be used as a data input for demultiplexing applications.

The LS139 comprises two separate two-line-to-four-line decoders in a single package. The active-low enable input can be used as a data line in demultiplexing applications.

All of these decoders/demultiplexers feature fully buffered inputs, presenting only one normalized load to its driving circuit. All inputs are clamped with high-performance

Schottky diodes to suppress line-ringing and simplify system design.

Features

YDesigned specifically for high speed: Memory decoders

Data transmission systems

YLS138 3-to-8-line decoders incorporates 3 enable inputs to simplify cascading and/or data reception

YLS139 contains two fully independent 2-to-4-line decoders/demultiplexers

YSchottky clamped for high performance

YTypical propagation delay (3 levels of logic)

LS138	21 ns
LS139	21 ns
Y Typical power dissipation
LS138	32 mW
LS139	34 mW
Y Alternate	Military/Aerospace devices (54LS138,

54LS139) are available. Contact a National Semiconductor Sales Office/Distributor for specifications.

Connection Diagrams

Dual-in-Line Package

Dual-in-Line Package

TL/F/6391 ± 1	TL/F/6391 ± 2
Order Number 54LS138DMQB, 54LS138FMQB,	Order Number 54LS139DMQB, 54LS139FMQB,
54LS138LMQB, DM54LS138J, DM54LS138W,	54LS139LMQB, DM54LS139J, DM54LS139W,
DM74LS138M or DM74LS138N	DM74LS139M or DM74LS139N
See NS Package Number E20A, J16A,	See NS Package Number E20A, J16A,
M16A, N16E or W16A	M16A, N16E or W16A

Decoders/Demultiplexers 54LS139/DM54LS139/DM74LS139

54LS138/DM54LS138/DM74LS138,

C1995 National Semiconductor Corporation

TL/F/6391

RRD-B30M105/Printed in U. S. A.

Absolute Maximum Ratings (Note)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications.

Supply Voltage	7V
Input Voltage	7V
Operating Free Air Temperature Range	b55§C to a125§C
DM54LS and 54LS
DM74LS	0§C to a70§C
Storage Temperature Range	b65§C to a150§C

Note: The ``Absolute Maximum Ratings'' are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the ``Electrical Characteristics'' table are not guaranteed at the absolute maximum ratings. The ``Recommended Operating Conditions'' table will define the conditions for actual device operation.

Recommended Operating Conditions

Symbol	Parameter		DM54LS138				DM74LS138			Units
		Min	Nom		Max	Min	Nom		Max
VCC	Supply Voltage	4.5	5		5.5	4.75	5		5.25	V
VIH	High Level Input Voltage	2				2				V
VIL	Low Level Input Voltage				0.7				0.8	V
IOH	High Level Output Current				b0.4				b0.4	mA
IOL	Low Level Output Current				4				8	mA
TA	Free Air Operating Temperature	b55			125	0			70	§C

'LS138 Electrical Characteristics

over recommended operating free air temperature range (unless otherwise noted)

Symbol	Parameter	Conditions		Min	Typ	Max	Units
					(Note 1)
VI	Input Clamp Voltage	VCC e Min, II e b18 mA				b1.5	V
VOH	High Level Output	VCC e Min, IOH e Max,	DM54	2.5	3.4		V
	Voltage	VIL e Max, VIH e Min	DM74	2.7	3.4
VOL	Low Level Output	VCC e Min, IOL e Max,	DM54		0.25	0.4
	Voltage	VIL e Max, VIH e Min	DM74		0.35	0.5	V
		IOL e 4 mA, VCC e Min	DM74		0.25	0.4
II	Input Current @ Max	VCC e Max, VI e 7V				0.1	mA
	Input Voltage
IIH	High Level Input Current	VCC e Max, VI e 2.7V				20	mA
IIL	Low Level Input Current	VCC e Max, VI e 0.4V				b0.36	mA
IOS	Short Circuit	VCC e Max	DM54	b20		b100	mA
	Output Current	(Note 2)	DM74	b20		b100
ICC	Supply Current	VCC e Max (Note 3)			6.3	10	mA
Note 1: All typicals are at VCC e 5V, TA e 25§C.

Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.

Note 3: ICC is measured with all outputs enabled and open.

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'LS138 Switching Characteristics

at VCC e 5V and TA e 25§C (See Section 1 for Test Waveforms and Output Load)

		From (Input)	Levels		RL e 2 kX
Symbol	Parameter	To (Output)	of Delay	CL e 15 pF		CL e 50 pF		Units
				Min	Max	Min	Max
tPLH	Propagation Delay Time	Select to	2		18		27	ns
	Low to High Level Output	Output
tPHL	Propagation Delay Time	Select to	2		27		40	ns
	High to Low Level Output	Output
tPLH	Propagation Delay Time	Select to	3		18		27	ns
	Low to High Level Output	Output
tPHL	Propagation Delay Time	Select to	3		27		40	ns
	High to Low Level Output	Output
tPLH	Propagation Delay Time	Enable to	2		18		27	ns
	Low to High Level Output	Output
tPHL	Propagation Delay Time	Enable to	2		24		40	ns
	High to Low Level Output	Output
tPLH	Propagation Delay Time	Enable to	3		18		27	ns
	Low to High Level Output	Output
tPHL	Propagation Delay Time	Enable to	3		28		40	ns
	High to Low Level Output	Output

Recommended Operating Conditions

Symbol	Parameter		DM54LS139				DM74LS139			Units
		Min	Nom		Max	Min	Nom		Max
VCC	Supply Voltage	4.5	5		5.5	4.75	5		5.25	V
VIH	High Level Input Voltage	2				2				V
VIL	Low Level Input Voltage				0.7				0.8	V
IOH	High Level Output Current				b0.4				b0.4	mA
IOL	Low Level Output Current				4				8	mA
TA	Free Air Operating Temperature	b55			125	0			70	§C

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