HD74ALVCH16821
3.3-V 20-bit Bus Interface Flip Flops with 3-state Outputs
ADE-205-171B (Z)
3rd. Edition
December 1999
Description
The HD74ALVCH16821 can be used as two 10-bit flip flops or one 20-bit flip flop. The 20 flip flops are
edge triggered D-type flip flops. On the positive transition of the clock (CLK) input, the device provides
true data at the Q outputs. A buffered output enable (OE) input can be used to place the ten outputs in
either a normal logic state (high or low levels) or a high impedance state. In the high impedance state, the
outputs neither load nor drive the bus lines significantly. The high impedance state and increased drive
provide the capability to drive bus line without need for interface or pullup components. The output enable
(OE) input does not affect the internal operations of the flip flops. Old data can be retained or new data can
be entered while the outputs are in the high impedance state. Active bus hold circuitry is provided to hold
unused or floating data inputs at a valid logic level.
Features
•
V
CC
= 2.3 V to 3.6 V
•
Typical V
OL
ground bounce < 0.8 V (@V
CC
= 3.3 V, Ta = 25°C)
•
Typical V
OH
undershoot > 2.0 V (@V
CC
= 3.3 V, Ta = 25°C)
•
High output current
±24
mA (@V
CC
= 3.0 V)
•
Bus hold on data inputs eliminates the need for external pullup / pulldown resistors
HD74ALVCH16821
Absolute Maximum Ratings
Item
Supply voltage
Input voltage
*1
Output voltage
*1, 2
Input clamp current
Output clamp current
Continuous output current
V
CC
, GND current / pin
Maximum power dissipation
at Ta = 55°C (in still air)
*3
Storage temperature
Notes:
Symbol
V
CC
V
I
V
O
I
IK
I
OK
I
O
I
CC
or I
GND
P
T
Tstg
Ratings
–0.5 to 4.6
–0.5 to 4.6
–0.5 to V
CC
+0.5
–50
±50
±50
±100
1
–65 to 150
Unit
V
V
V
mA
mA
mA
mA
W
°C
TSSOP
V
I
< 0
V
O
< 0 or V
O
> V
CC
V
O
= 0 to V
CC
Conditions
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage
to the device. These are stress ratings only, and functional operation of the device at these or
any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute maximum rated conditions for extended periods may affect device
reliability.
1. The input and output negative voltage ratings may be exceeded if the input and output clamp
current ratings are observed.
2. This value is limited to 4.6 V maximum.
3. The maximum package power dissipation is calculated using a junction temperature of 150°C
and a board trace length of 750 mils.
Recommended Operating Conditions
Item
Supply voltage
Input voltage
Output voltage
High level output current
Symbol
V
CC
V
I
V
O
I
OH
Min
2.3
0
0
—
—
—
Low level output current
I
OL
—
—
—
Input transition rise or fall rate
Operating temperature
∆t
/
∆v
Ta
0
–40
Max
3.6
V
CC
V
CC
–12
–12
–24
12
12
24
10
85
ns / V
°C
mA
Unit
V
V
V
mA
V
CC
= 2.3 V
V
CC
= 2.7 V
V
CC
= 3.0 V
V
CC
= 2.3 V
V
CC
= 2.7 V
V
CC
= 3.0 V
Conditions
Note: Unused control inputs must be held high or low to prevent them from floating.
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