ST M74HC238 User Manual
M74HC238
3 TO 8 LINE DECODER
■HIGH SPEED:
tPD = 15ns (TYP.) at VCC = 6V
■LOW POWER DISSIPATION: ICC = 4μA(MAX.) at TA=25°C
■HIGH NOISE IMMUNITY: VNIH = VNIL = 28 % VCC (MIN.)
■SYMMETRICAL OUTPUT IMPEDANCE: |IOH| = IOL = 4mA (MIN)
■BALANCED PROPAGATION DELAYS: tPLH tPHL
■WIDE OPERATING VOLTAGE RANGE: VCC (OPR) = 2V to 6V
■PIN AND FUNCTION COMPATIBLE WITH 74 SERIES 238
DESCRIPTION
DIP |
SOP |
TSSOP |
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ORDER CODES |
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PACKAGE |
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TUBE |
T & R |
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DIP |
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M74HC238B1R |
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SOP |
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M74HC238M1R |
M74HC238RM13TR |
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TSSOP |
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M74HC238TTR |
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The M74HC238 is an high speed CMOS 3 TO 8 LINE DECODER fabricated with silicon gate C2MOS technology.
If the device is enabled, 3 binary select inputs (A, B and C) determine which one of outputs will go high. When enable input G1 is held "Low" or either G2A or G2B is held "High" decoding function is
inhibited and all the 8 outputs go low. Three enable inputs are provided to ease cascade connection and application of this address decoder in memory systems.
All inputs are equipped with protection circuits against static discharge and transient excess voltage.
PIN CONNECTION AND IEC LOGIC SYMBOLS
July 2001 |
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M74HC238
INPUT AND OUTPUT EQUIVALENT CIRCUIT |
PIN DESCRIPTION |
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PIN No |
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SYMBOL |
NAME AND FUNCTION |
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1, 2, 3 |
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A, B, C |
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Data Inputs |
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4, 5 |
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G2A G2B |
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Enable Input (Active |
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LOW) |
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6 |
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G1 |
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Data Enable Input (Active |
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HIGH) |
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15, 14, 13, |
Y0 to Y7 |
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Outputs |
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12, 11, 10, 9, |
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7 |
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8 |
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GND |
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Ground (0V) |
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16 |
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VCC |
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Positive Supply Voltage |
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TRUTH TABLE |
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INPUTS |
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OUTPUTS |
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ENABLE |
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SELECT |
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SELECTED |
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OUTPUT |
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G2B |
G2A |
G1 |
C |
B |
A |
Y0 |
Y1 |
Y2 |
Y3 |
Y4 |
Y5 |
Y6 |
Y7 |
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X |
X |
L |
X |
X |
X |
L |
L |
L |
L |
L |
L |
L |
L |
NONE |
X |
H |
X |
X |
X |
X |
L |
L |
L |
L |
L |
L |
L |
L |
NONE |
H |
X |
X |
X |
X |
X |
L |
L |
L |
L |
L |
L |
L |
L |
NONE |
L |
L |
H |
L |
L |
L |
H |
L |
L |
L |
L |
L |
L |
L |
Y0 |
L |
L |
H |
L |
L |
H |
L |
H |
L |
L |
L |
L |
L |
L |
Y1 |
L |
L |
H |
L |
H |
L |
L |
L |
H |
L |
L |
L |
L |
L |
Y2 |
L |
L |
H |
L |
H |
H |
L |
L |
L |
H |
L |
L |
L |
L |
Y3 |
L |
L |
H |
H |
L |
L |
L |
L |
L |
L |
H |
L |
L |
L |
Y4 |
L |
L |
H |
H |
L |
H |
L |
L |
L |
L |
L |
H |
L |
L |
Y5 |
L |
L |
H |
H |
H |
L |
L |
L |
L |
L |
L |
L |
H |
L |
Y6 |
L |
L |
H |
H |
H |
H |
L |
L |
L |
L |
L |
L |
L |
H |
Y7 |
X : Don’t Care
LOGIC DIAGRAM
This logic diagram has not be used to estimate propagation delays
2/10
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M74HC238 |
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ABSOLUTE MAXIMUM RATINGS |
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Symbol |
Parameter |
Value |
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Unit |
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VCC |
Supply Voltage |
-0.5 to +7 |
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V |
VI |
DC Input Voltage |
-0.5 to VCC + 0.5 |
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V |
VO |
DC Output Voltage |
-0.5 to VCC + 0.5 |
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V |
IIK |
DC Input Diode Current |
± 20 |
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mA |
IOK |
DC Output Diode Current |
± 20 |
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mA |
IO |
DC Output Current |
± 25 |
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mA |
ICC or IGND |
DC VCC or Ground Current |
± 50 |
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mA |
PD |
Power Dissipation |
500(*) |
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mW |
Tstg |
Storage Temperature |
-65 to +150 |
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°C |
TL |
Lead Temperature (10 sec) |
300 |
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°C |
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied
(*) 500mW at 65 °C; derate to 300mW by 10mW/°C from 65°C to 85°C
RECOMMENDED OPERATING CONDITIONS
Symbol |
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Parameter |
Value |
Unit |
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VCC |
Supply Voltage |
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2 to 6 |
V |
VI |
Input Voltage |
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0 to VCC |
V |
VO |
Output Voltage |
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0 to VCC |
V |
Top |
Operating Temperature |
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-55 to 125 |
°C |
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Input Rise and Fall Time |
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VCC = 2.0V |
0 to 1000 |
ns |
tr, tf |
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VCC = 4.5V |
0 to 500 |
ns |
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VCC = 6.0V |
0 to 400 |
ns |
3/10
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