Page 36 - EE2449_TTL_Datasheet

SN54/74LS155
DUAL 1-OF-4 DECODER/ SN54/74LS156

DEMULTIPLEXER

The SN54/74LS155 and SN54/74LS156 are high speed Dual 1-of-4
Decoder/Demultiplexers. These devices have two decoders with common
2-bit Address inputs and separate gated Enable inputs. Decoder “a” has an DUAL 1-OF-4 DECODER/
Enable gate with one active HIGH and one active LOW input. Decoder “b” has
two active LOW Enable inputs. If the Enable functions are satisfied, one DEMULTIPLEXER
output of each decoder will be LOW as selected by the address inputs. The LS156-OPEN-COLLECTOR
LS156 has open collector outputs for wired-OR (DOT-AND) decoding and
LOW POWER SCHOTTKY
function generator applications.
The LS155 and LS156 are fabricated with the Schottky barrier diode
process for high speed and are completely compatible with all Motorola TTL
families.
• Schottky Process for High Speed
J SUFFIX
• Multifunction Capability CERAMIC
• Common Address Inputs CASE 620-09
16
• True or Complement Data Demultiplexing
1
• Input Clamp Diodes Limit High Speed Termination Effects
• ESD > 3500 Volts

N SUFFIX
PLASTIC
CASE 648-08
16
CONNECTION DIAGRAM DIP (TOP VIEW) 1
V CC E b E b A 0 O 3b O 2b O 1b O 0b
16 15 14 13 12 11 10 9
D SUFFIX
NOTE:
The Flatpak version SOIC
16
has the same pinouts 1 CASE 751B-03
(Connection Diagram) as
the Dual In-Line Package.
ORDERING INFORMATION
1 2 3 4 5 6 7 8 SN54LSXXXJ Ceramic
E a E a A 1 O 3a O 2a O 1a O 0a GND SN74LSXXXN Plastic
SN74LSXXXD SOIC

LOGIC SYMBOL
PIN NAMES LOADING (Note a)
HIGH LOW 1 2 13 3 14 15
A 0 , A 1 Address Inputs 0.5 U.L. 0.25 U.L.
E a , E b Enable (Active LOW) Inputs 0.5 U.L. 0.25 U.L.
E a Enable (Active HIGH) Input 0.5 U.L. 0.25 U.L.
E E
O 0 –O 3 Active LOW Outputs (Note b) 10 U.L. 5 (2.5) U.L. A 0 A 0
DECODER a DECODER b
NOTES: A 1 A 1
a) 1 TTL Unit Load (U.L.) = 40 mA HIGH/1.6 mA LOW. 0 1 2 3 0 1 2 3
b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74)
Temperature Ranges. The HIGH level drive for the LS156 must be established by an external
resistor. 7 6 5 4 9 10 11 12
V CC = PIN 16
GND = PIN 8

FAST AND LS TTL DATA
5-150
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