
HD74HC155
Dual 2-to-4-line Decoders/Demultiplexers
Description
This circuit features dual 1-line-to-4-line demultiplexer with individual strobes and common binary-address
input. When both sections are enabled by the strobes, the common binary-address inputs sequentially
select and route associated input data to the appropriate output of each section. The individual strobes
permit activating or inhibiting each of the 4-bit sections as desired. Data applied to input 1C is inverted
through its outputs. The inverter following the 1C data input permits use as a 3-to-8-line decoder or 1-to-8line demultiplexer without external gating.
Features
• High Speed Operation: tpd (A or B to Y) = 15 ns typ (CL = 50 pF)
• High Output Current: Fanout of 10 LSTTL Loads
• Wide Operating Voltage: VCC = 2 to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)
Function Table
2-line-to-4-line Decoder/1-line-to-4-line Demultiplexer
Inputs
Select Strobe Data Outputs
B A 1G 1C 1Y
XXHXHHHH
LLLHLHHH
LH L H H L H H
HL L HHHL H
HHL HHHHL
XXXL HHHH
0
1Y
1
1Y
2
1Y
3

HD74HC155
Inputs
Select Strobe Data Outputs
B A 2G 2C 2Y
0
XXHXHHHH
LLLLLHHH
LH L L H L H H
HL L L HHL H
HHL L HHHL
XXXHHHHH
3-line-to-8-line Decoder/1-line-to-8-line Demultiplexer
Inputs Outputs
Select Strobe Data 0 1 2 3 4 5 6 7
CBAG 2Y02Y
XXXH HHHHHHHH
LLLL L HHHHHHH
LLHL HL HHHHHH
LHLL HHLHHHHH
LHHL HHHLHHHH
HLLL HHHHL HHH
HLHL HHHHHLHH
HHLL HHHHHHL H
HHHL HHHHHHHL
Notes: 1. C: inputs 1C and 2C connected together
2. G: inputs 1G and 2G connected together
3. X: irrelevant
2Y
1
2
2Y
3
2Y
1
1Y
2Y
2
1Y
0
1
1Y
2Y
3
1Y
2
3
2

HD74HC155
DC Characteristics
Ta = –40 to
Ta = 25°C
Item Symbol V
Input voltage V
IH
(V) Min Typ Max Min Max Unit Test Conditions
CC
2.0 1.5 — — 1.5 — V
4.5 3.15 — — 3.15 —
6.0 4.2 — — 4.2 —
V
IL
2.0 — — 0.5 — 0.5 V
4.5 — — 1.35 — 1.35
6.0 — — 1.8 — 1.8
Output voltage V
OH
2.0 1.9 2.0 — 1.9 — V Vin = VIH or VILIOH = –20 µA
4.5 4.4 4.5 — 4.4 —
6.0 5.9 6.0 — 5.9 —
4.5 4.18 — — 4.13 — IOH = –4 mA
6.0 5.68 — — 5.63 — IOH = –5.2 mA
V
OL
2.0 — 0.0 0.1 — 0.1 V Vin = VIH or VILIOL = 20 µA
4.5 — 0.0 0.1 — 0.1
6.0 — 0.0 0.1 — 0.1
4.5 — — 0.26 — 0.33 IOL = 4 mA
6.0 — — 0.26 — 0.33 IOL = 5.2 mA
Input current Iin 6.0 — — ±0.1 — ±1.0 µA Vin = VCC or GND
Quiescent supply
I
CC
6.0 — — 4.0 — 40 µA Vin = VCC or GND, Iout = 0 µA
current
+85°C
4

AC Characteristics (CL = 50 pF, Input tr = tf = 6 ns)
Ta = –40 to
Ta = 25°C
Item Symbol V
Propagation delay t
time t
PLH
PHL
(V) Min Typ Max Min Max Unit Test Conditions
CC
2.0 — — 160 — 200 ns A, B, 2C, 1G or 2G to Y
4.5 — 13 32 — 40
6.0 — — 27 — 34
2.0 — — 160 — 200 A or B to Y
4.5 — 15 32 — 40
6.0 — — 27 — 34
2.0 — — 145 — 180 1C to Y
4.5 — 14 29 — 36
6.0 — — 25 — 31
Output rise/fall t
time t
TLH
THL
2.0 — — 75 — 95 ns
4.5 — 5 15 — 19
6.0 — — 13 — 16
Input capacitance Cin — — 5 10 — 10 pF
+85°C
HD74HC155
5

19.20
20.00 Max
16 9
1.3
Unit: mm
6.30
7.40 Max
81
1.11 Max
2.54 ± 0.25
0.48 ± 0.10
5.06 Max
2.54 Min
0.51 Min
Hitachi Code
JEDEC
EIAJ
Weight
7.62
+ 0.13
0.25
– 0.05
0° – 15°
(reference value)
DP-16
Conforms
Conforms
1.07 g

16
Unit: mm
10.06
10.5 Max
9
5.5
1
0.80 Max
1.27
*0.42 ± 0.08
0.40 ± 0.06
*Dimension including the plating thickness
Base material dimension
8
0.12
0.10 ± 0.10
0.15
M
2.20 Max
7.80
0.20 ± 0.04
*0.22 ± 0.05
0.70 ± 0.20
Hitachi Code
JEDEC
EIAJ
(reference value)
Weight
+ 0.20
– 0.30
1.15
0° – 8°
FP-16DA
—
Conforms
0.24 g

16
Unit: mm
9.9
10.3 Max
9
1
1.27
0.635 Max
*0.42 ± 0.08
0.40 ± 0.06
*Dimension including the plating thickness
Base material dimension
8
0.25
+ 0.11
– 0.04
0.14
0.15
3.95
1.75 Max
M
6.10
1.08
0.20 ± 0.03
*0.22 ± 0.03
0.60
Hitachi Code
JEDEC
EIAJ
Weight
+ 0.10
– 0.30
0° – 8°
+ 0.67
– 0.20
(reference value)
FP-16DN
Conforms
Conforms
0.15 g

Cautions
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intellectual property rights, in connection with use of the information contained in this document.
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received the latest product standards or specifications before final design, purchase or use.
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contact Hitachi’s sales office before using the product in an application that demands especially high
quality and reliability or where its failure or malfunction may directly threaten human life or cause risk
of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation,
traffic, safety equipment or medical equipment for life support.
4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly
for maximum rating, operating supply voltage range, heat radiation characteristics, installation
conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used
beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable
failure rates or failure modes in semiconductor devices and employ systemic measures such as failsafes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other
consequential damage due to operation of the Hitachi product.
5. This product is not designed to be radiation resistant.
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