HITACHI HD74HC688

HD74HC688
8-bit Magnitude Comparator
Description
The HD74HC688 compares bit for bit two 8-bit words and indicates whether or not they are equal. The
P=Q output indicates equality when it is low.
A single active low enable is provided to facilitate cascading of several packages and enable comparison of
words greater than 8-bits.
This device is useful in memory block decoding applications, where memory block enable signals must be
generated from computer address information.
Features
•
•
•
•
•
High Speed Operation: tpd (P or Q to Output) = 17 ns typ (C L = 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
Input
Data P, Q
Enable G
P=Q
P=Q
L
L
P>Q
L
H
P<Q
L
H
X
H
H
HD74HC688
Pin Arrangement
G
1
20 VCC
P0
2
19 P=Q
Q0
3
18 Q7
P1
4
17 P7
Q1
5
16 Q6
P2
6
15 P6
Q2
7
14 Q5
P3
8
13 P5
Q3
9
12 Q4
GND 10
11 Q4
(Top view)
2
HD74HC688
Block Diagram
P0
Q0
P1
Q1
P2
Q2
P3
Q3
P4
P=Q
Q4
P5
Q5
P6
Q6
P7
Q7
G
3
HD74HC688
DC Characteristics
Ta = –40 to
+85°C
Ta = 25°C
Item
Symbol
VCC (V) Min Typ Max Min
Max
Unit
Input voltage
VIH
2.0
1.5 —
—
1.5
—
V
4.5
3.15 —
—
3.15
—
6.0
4.2 —
—
4.2
—
2.0
—
—
0.5
—
0.5
4.5
—
—
1.35 —
1.35
6.0
—
—
1.8
—
1.8
2.0
1.9 2.0 —
1.9
—
4.5
4.4 4.5 —
4.4
—
6.0
5.9 6.0 —
5.9
—
4.5
4.18 —
—
4.13
—
I OH = –4 mA
6.0
5.68 —
—
5.63
—
I OH = –5.2 mA
2.0
—
0.0 0.1
—
0.1
4.5
—
0.0 0.1
—
0.1
6.0
—
0.0 0.1
—
0.1
4.5
—
—
0.26 —
0.33
I OL = 4 mA
6.0
—
—
0.26 —
0.33
I OL = 5.2 mA
VIL
Output voltage
VOH
VOL
Test Conditions
V
V
V
Vin = VIH or VIL I OH = –20 µA
Vin = VIH or VIL I OL = 20 µA
Input current
Iin
6.0
—
—
±0.1 —
±1.0
µA
Vin = VCC or GND
Quiescent supply
current
I CC
6.0
—
—
4.0
40
µA
Vin = VCC or GND, Iout = 0 µA
4
—
HD74HC688
AC Characteristics (CL = 50 pF, Input tr = tf = 6 ns)
Ta = –40 to
+85°C
Ta = 25°C
VCC (V) Min Typ Max Min
Max
Unit
Test Conditions
Propagation delay t PLH
2.0
—
—
210 —
265
ns
P or Q to output
time
4.5
—
17
42
—
53
6.0
—
—
36
—
45
t PLH
2.0
—
—
120 —
150
ns
Enable to P=Q
t PHL
4.5
—
9
24
—
30
6.0
—
—
20
—
26
Item
Symbol
t PHL
Output rise/fall
t TLH
2.0
—
—
75
—
95
time
t THL
4.5
—
5
15
—
19
6.0
—
—
13
—
16
—
—
5
10
—
10
Input capacitance
Cin
ns
pF
5
Unit: mm
24.50
25.40 Max
6.30
11
1
7.00 Max
20
10
1.30
2.54 ± 0.25
0.48 ± 0.10
0.51 Min
1.27 Max
2.54 Min 5.08 Max
0.89
7.62
+ 0.11
0.25 – 0.05
0° – 15°
Hitachi Code
JEDEC
EIAJ
Weight (reference value)
DP-20N
—
Conforms
1.26 g
Unit: mm
12.6
13 Max
11
1
10
1.27
*0.42 ± 0.08
0.40 ± 0.06
0.10 ± 0.10
0.80 Max
*0.22 ± 0.05
0.20 ± 0.04
2.20 Max
5.5
20
0.20
7.80 +– 0.30
1.15
0° – 8°
0.70 ± 0.20
0.15
0.12 M
*Dimension including the plating thickness
Base material dimension
Hitachi Code
JEDEC
EIAJ
Weight (reference value)
FP-20DA
—
Conforms
0.31 g
Unit: mm
12.8
13.2 Max
11
1
10
0.20 ± 0.10
0.935 Max
1.27
*0.42 ± 0.08
0.40 ± 0.06
*0.27 ± 0.05
0.25 ± 0.04
2.65 Max
7.50
20
0.25
10.40 +– 0.40
1.45
0° – 8°
0.57
0.70 +– 0.30
0.15
0.12 M
*Dimension including the plating thickness
Base material dimension
Hitachi Code
JEDEC
EIAJ
Weight (reference value)
FP-20DB
Conforms
—
0.52 g
Cautions
1. Hitachi neither warrants nor grants licenses of any rights of Hitachi’s or any third party’s patent,
copyright, trademark, or other intellectual property rights for information contained in this document.
Hitachi bears no responsibility for problems that may arise with third party’s rights, including
intellectual property rights, in connection with use of the information contained in this document.
2. Products and product specifications may be subject to change without notice. Confirm that you have
received the latest product standards or specifications before final design, purchase or use.
3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However,
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.
6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without
written approval from Hitachi.
7. Contact Hitachi’s sales office for any questions regarding this document or Hitachi semiconductor
products.
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