1/10April 2001
■HIGH SPE ED: t PD = 4.5ns (TYP.) at VCC = 5 V
■LOW POWER DISSIPATION:
ICC = 4µA(MAX.) at TA=25°C
■HIGH NOISE IMMUNITY:
VNIH = VNIL = 28 % VCC (MIN.)
■50Ω TRANSMISSION LINE DRIVING
CAPABILITY
■SYMMETRICAL OUTPUT IMPEDANCE:
|IOH| = IOL = 24m A (MIN)
■BALANCED PROPAGATION DELAYS:
tPLH ≅ tPHL
■OPERATING VOLTAGE RAN GE:
VCC (O PR) = 2V to 6V
■PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 138
■IMPROVED LATCH-U P IMMUNITY
DESCRIPTION
The 74AC138 is an advanced high-speed CMOS
3 TO 8 LINE DE CODER (INVERTING) fabricated
with sub-micron silicon gate and double-layer
metal wiring C2MOS tecnology.
If the device is enabl ed, 3 binary select inputs (A,
B, and C) determine whic h o ne of the out puts will
go low. If enable input G1 is held low or either G2A
or G2B is held high, the decoding function is
inhibited and all the 8 output s go t o high.
Tree e nable inpu ts are provided to ease cascade
connection and application of address decoders
for memory systems.
All inputs and outputs are equipped with
protection circuits aga inst static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
74AC138
3 TO 8 LINE DECODER (INVERTING)
PIN CONNECTION AND IEC LOGIC SYMBOLS
ORDER CODES
PACKAGE TUBE T & R
DIP 74AC138B
SOP 74AC138M 74AC138MTR
TSSOP 74AC138TTR
TSSOPDIP SOP
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INPUT AND OUT PUT EQUIVALENT CIRCUIT PIN DESCRIPTION
TRUTH TABLE
X : Don’t Care
LOGIC DIAGRAM
Th i s l ogic dia gram has not be used to estimat e propagation del ays
PIN No SYMBOL NAME AND FUNCTION
1, 2, 3 A, B, C Address Inputs
4, 5 G2A, G2B Enable Inputs
6 G1 Enable Input
15, 14, 13,
12, 11, 10, 9,
7
Y0 to Y7 Outputs
8 GND Ground (0V)
16 VCC Positive Supply Voltage
INPUTS OUTPUTS
ENABLE SELECT
G2B G2A G1CBAY0Y1 Y2 Y3 Y4 Y5 Y6 Y7
XXLXXXHHHHHHHH
XHXXXXHHHHHHHH
HXXXXXHHHHHHHH
LLHLLLLHHHHHHH
LLHLLHHLHHHHHH
LLHLHLHHLHHHHH
LLHLHHHHHLHHHH
LLHHLLHHHHLHHH
LLHHLHHHHHHLHH
LLHHHLHHHHHHLH
LLHHHHHHHHHHHL
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ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings are t hose v alues beyond which damage to the device may occur. Functional operation under these conditions is
not implie d .
RECOMMENDE D OPERATING CONDITIONS
1) VIN f rom 30% t o 70% of VCC
Symbol Parameter Value Unit
VCC Supply Voltage -0.5 to +7 V
VIDC Input Voltage -0.5 to VCC + 0.5 V
VODC Output Volta ge -0.5 to VCC + 0.5 V
IIK DC Input Diode Current ± 20 mA
IOK DC Output Diode Current ± 20 mA
IODC Output Current ± 50 mA
ICC or IGND DC VCC or Ground Curre nt ± 400 mA
Tstg Storage Temperature -65 to +150 °C
TLLead Temperature (10 sec) 300 °C
Symbol Parameter Value Unit
VCC Supply Voltage 2 to 6 V
VIInput Voltage 0 to VCC V
VOOutput Voltage 0 to VCC V
Top Operating Temperature -55 to 125 °C
dt/dv Input Rise and Fall Time VCC = 3.0, 4.5 or 5.5V (note 1) 8 ns/V
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DC SPE CIFI CATI ONS
1) M aximum test du rat i on 2ms, one output loaded at time
2 ) I nciden t wave sw i tc hi ng is gu aranteed on tran sm i ssion l i nes with impedances a s l ow a s 50Ω
Symbol Parameter
Test Condition Value
Unit
VCC
(V)
TA = 25°C -40 to 85°C -55 to 125°C
Min. Typ. Max. Min. Max. Min. Max.
VIH High Level Input
Voltage 3.0 VO = 0.1 V or
VCC-0.1V
2.1 1.5 2.1 2.1 V4.5 3.15 2.25 3.15 3.15
5.5 3.85 2.75 3.85 3.85
VIL Low Level Input
Voltage 3.0 VO = 0.1 V or
VCC-0.1V
1.5 0.9 0.9 0.9 V4.5 2.25 1.35 1.35 1.35
5.5 2.75 1.65 1.65 1.65
VOH High Level Output
Voltage 3.0 IO=-50 µA2.9 2.99 2.9 2.9
V
4.5 IO=-50 µA4.4 4.49 4.4 4.4
5.5 IO=-50 µA5.4 5.49 5.4 5.4
3.0 IO=-12 mA 2.56 2.46 2.4
4.5 IO=-24 mA 3.86 3.76 3.7
5.5 IO=-24 mA 4.86 4.76 4.7
VOL Low Level Output
Voltage 3.0 IO=50 µA0.002 0.1 0.1 0.1
V
4.5 IO=50 µA0.001 0.1 0.1 0.1
5.5 IO=50 µA0.001 0.1 0.1 0.1
3.0 IO=12 mA 0.36 0.44 0.5
4.5 IO=24 mA 0.36 0.44 0.5
5.5 IO=24 mA 0.36 0.44 0.5
IIInput Leakage
Current 5.5 VI = VCC or GND ± 0.1 ± 1 ± 1 µA
ICC Quiescent Supply
Current 5.5 VI = VCC or GND 44080µA
I
OLD Dynamic Output
Current (note 1, 2) 5.5 VOLD = 1.65 V max 75 50 mA
IOHD VOHD = 3.85 V min -75 -50 mA
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AC EL ECTRI CAL CHARACTERISTICS (CL = 50 pF, RL = 500 Ω, Input tr = tf = 3 ns)
(*) Vol tage ra ng e i s 3.3V ± 0.3V
(**) Voltage range is 5.0V ± 0.5V
CAPACITIVE CHARACT ERISTICS
1) C PD is defined as the value of t he IC’s internal equivalent capacitance which is calculated f rom the operating current cons umption without
load. (Refer to Test Ci rcuit). Average operating current can be obtained by t he following equation. ICC(opr) = CPD x VCC x fIN + ICC/n ( per c ircuit )
TEST CIRCUIT
CL = 50p F or equiva l ent (i nclud es jig and p robe capac i tance)
RL = R1 = 5 00Ω or equivalent
RT = ZOUT of pulse ge nerator (typically 50Ω)
Symbol Parameter
Test Condition Value
Unit
VCC
(V)
TA = 25°C -40 to 85°C -55 to 125°C
Min. Typ. Max. Min. Max. Min. Max.
tPLH tPHL Propagation Delay
Time
A, B, C to Y
3.3(*) 1.5 5.5 10.5 1.5 14.0 1.5 15.4 ns
5.0(**) 1.5 4.5 9.0 1.5 10.0 1.5 11.0
tPLH tPHL Propagation Delay
Time
G1 to Y
3.3(*) 1.5 6.0 10.5 1.5 14.0 1.5 15.4 ns
5.0(**) 1.5 4.5 11.0 1.5 10.0 1.5 11.0
tPLH tPHL Propagation Delay
Time
G2A or G2B to Y
3.3(*) 1.5 5.5 10.5 1.5 12.7 1.5 14.0 ns
5.0(**) 1.5 4.5 9.0 1.5 10.0 1.5 10.0
Symbol Parameter
Test Condition Value
Unit
VCC
(V)
TA = 25°C -40 to 85°C -55 to 125°C
Min. Typ. Max. Min. Max. Min. Max.
CIN Input Capacitance 5.0 4 pF
CPD Power Dissipation
Capacitance
(note 1)
5.0 fIN = 10MHz 60 pF
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WAVEFORM 1: PROPAGATION DELAYS FOR INVERTING OUT PUT S (f=1 MHz; 50% duty cycle)
WAVEFORM 2: PROPAGATION DELAYS FOR NON-INVERTING OUTPUTS (f=1MHz; 50% duty cycle)
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DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
a1 0.51 0.020
B 0.77 1.65 0.030 0.065
b0.5 0.020
b1 0.25 0.010
D200.787
E8.5 0.335
e2.54 0.100
e3 17.78 0.700
F7.10.280
I5.10.201
L3.3 0.130
Z1.270.050
P001C
Plastic DIP-16 (0.25) MECHANICAL DATA
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DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
A1.750.068
a1 0.1 0.2 0.004 0.007
a2 1.65 0.064
b 0.35 0.46 0.013 0.018
b1 0.19 0.25 0.007 0.010
C0.5 0.019
c1 45 (typ.)
D 9.8 10 0.385 0.393
E 5.8 6.2 0.228 0.244
e1.27 0.050
e3 8.89 0.350
F 3.8 4.0 0.149 0.157
G 4.6 5.3 0.181 0.208
L 0.5 1.27 0.019 0.050
M0.620.024
S8 (max.)
P013H
SO-16 MECHANICAL DATA
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DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
A1.10.433
A1 0.05 0.10 0.15 0.002 0.004 0.006
A2 0.85 0.9 0.95 0.335 0.354 0.374
b 0.19 0.30 0.0075 0.0118
c 0.09 0.20 0.0035 0.0079
D 4.9 5 5.1 0.193 0.197 0.201
E 6.25 6.4 6.5 0.246 0.252 0.256
E1 4.3 4.4 4.48 0.169 0.173 0.176
e 0.65 BSC 0.02 56 BSC
K0
o4
o8
o0
o4
o8
o
L 0.50 0.60 0.70 0.020 0.024 0.028
cE
b
A2
A
E1
D
1
PIN 1 IDENTIFICATION
A1 L
K
e
TSSOP16 MECHANICAL DATA
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