ST M74HC688 User Manual
M74HC688
8 BIT EQUALITY COMPARATOR
■ HIGH SPEED:
t
= 17ns (TYP.) at VCC = 6V
PD
■ LOW POWER DISSIPATION:
I
= 4µA(MAX.) at TA=25°C
CC
■ HIGH NOISE IMMUNITY:
V
= V
NIH
■ SYMMETRICAL OUTPUT IMPEDANCE:
|I
| = IOL = 4mA (MIN)
OH
■ BALANCED PROPAGATION DELAYS:
t
≅ t
PLH
■ WIDE OPERATING VOLTAGE RANGE:
V
(OPR) = 2V to 6V
CC
■ PIN AND FUNCTION COMPATIBLE WITH
= 28 % VCC (MIN.)
NIL
PHL
74 SERIES 688
DESCRIPTION
The M74HC688 is an high speed CMOS 8 BIT
EQUALITY COMPARATOR fabricated with silicon
gate C
2
MOS technology.
The M74HC688 compares bit for bit two 8-bit
words applied on inputs P0 - P7 and inputs Q0 Q7 and indicates whether or not they are equal. A
TSSOPDIP SOP
ORDER CODES
PACKAGE TUBE T & R
DIP M74HC688B1R
SOP M74HC688M1R M74HC688RM13TR
TSSOP M74HC688TTR
single active low enable is provided to facilitate
cascading several packages to enable
comparison of words greater than 8 bits.
All inputs are equipped with protection circuits
against static discharge and transient excess
voltage.
PIN CONNECTION AND IEC LOGIC SYMBOLS
1/9July 2001
M74HC688
INPUT AND OUTPUT EQUIVALENT CIRCUIT PIN DESCRIPTION
PIN No SYMBOL NAME AND FUNCTION
1G
2, 4, 6, 8, 1 1,
13, 15, 17
3, 5, 7, 9, 12,
14, 16, 18
19 P = Q
10 GND Ground (0V)
20 V
TRUTH TABLE
INPUTS OUTPUT
P0 to P7 Word Inputs
Q0 to Q7 Word Outputs
CC
Enable Input (Active
LOW)
Equal to Output
Positive Supply Voltage
P, Q G
P = Q L L
P <> Q L H
XHH
X: Don’t Care
LOGIC DIAGRAM
P = Q
This log i c diagram has not be used to est i m at e propagation delays
2/9
M74HC688
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
V
V
V
I
I
OK
I
I
or I
CC
P
T
T
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
RECOMMENDED OPERATING CONDITIONS
Symbol Parameter Value Unit
V
V
V
T
t
r
Supply Voltage
CC
DC Input Voltage -0.5 to VCC + 0.5
I
DC Output Voltage -0.5 to VCC + 0.5
O
DC Input Diode Current
IK
DC Output Diode Current
DC Output Current
O
DC VCC or Ground Current
GND
Power Dissipation
D
Storage Temperature
stg
Lead Temperature (10 sec)
L
°C; derate to 300mW by 10mW/°C from 65°C to 85°C
Supply Voltage
CC
Input Voltage 0 to V
I
Output Voltage 0 to V
O
Operating Temperature
op
Input Rise and Fall Time VCC = 2.0V
, t
f
V
V
CC
CC
= 4.5V
= 6.0V
-0.5 to +7 V
± 20 mA
± 20 mA
± 25 mA
± 50 mA
500(*) mW
-65 to +150 °C
300 °C
2 to 6 V
CC
CC
-55 to 125 °C
0 to 1000 ns
0 to 500 ns
0 to 400 ns
V
V
V
V
3/9
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