HD74ALVC16835
18-bit Universal Bus Driver with 3-state Outputs
ADE-205-192E (Z)
Preliminary
6th. Edition
January 1999
Description
The HD74ALVC16835 is an 18-bit universal bus driver designed for 2.3 V to 3.6 V V
CC
operation.
Data flow from A to Y is controlled by output enable (
OE). The device operates in the transparent mode
when the latch enable (LE) input is high. The A data is latched if the clock (CLK) input is held at a high or
low logic level. If LE is low, the A data is stored in the latch/flip flop on the low to high transition of the
CLK. When
OE is high, the outputs are in the high impedance state.
To ensure the high impedance state during power up or power down,
OE should be tied to V
CC
through a
pullup registor; the minimum value of the registor is determined by the current sinking capability of the
driver.
Features
Meets "PC SDRAM registered DIMM design support document, Rev. 1.2"
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)
HD74ALVC16835
2
Function Table
Inputs
OE
LE
CLK
A
Output Y
H
X
X
X
Z
L
H
X
L
L
L
H
X
H
H
L
L
L
L
L
L
H
H
L
L
H
X
Y
0
*1
L
L
L
X
Y
0
*2
H :
High level
L :
Low level
X :
Immaterial
Z :
High impedance
:
Low to high transition
Notes: 1. Output level before the indicated steady-state input conditions were established, provided that
CLK was high before LE went low.
2. Output level before the indicated steady-state input conditions were established.
HD74ALVC16835
4
Absolute Maximum Ratings
Item
Symbol
Ratings
Unit
Conditions
Supply voltage range
V
CC
0.5 to 4.6
V
Input voltage range
*1
V
I
0.5 to 4.6
V
Output voltage range
*1,
2
V
O
0.5 to V
CC
+0.5
V
Input clamp current
I
IK
50
mA
V
I
< 0
Output clamp current
I
OK
50
mA
V
O
< 0 or V
O
> V
CC
Continuous output current
I
O
50
mA
V
O
= 0 to V
CC
V
CC
, GND current / pin
I
CC
or I
GND
100
mA
Maximum power dissipation
at Ta = 55
C (in still air)
*3
P
T
1
W
TSSOP
Storage temperature range
Tstg
65 to 150
C
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 condition" is not implied. Exposure to absolute-
maximum-rated conditions for extended periods may affect device reliability.
Notes: 1. The input and output negative-voltage ratings may be exceeded if the input and output clamp
current ratings are observed.
2. The input and output positive-voltage ratings may be exceeded up to 4.6 V if the input and output
clamp-current ratings are observed.
3. The maximum power dissipation is calculated using a junction temperature of 150
C and board
trace length of 750 mils.
Recommended Operating Conditions
Item
Symbol
Min
Max
Unit
Conditions
Supply voltage
V
CC
2.3
3.6
V
Input voltage
V
I
0
V
CC
V
Output voltage
V
O
0
V
CC
V
High-level output current
I
OH
--
12
mA
V
CC
= 2.3 V
--
12
V
CC
= 2.7 V
--
24
V
CC
= 3.0 V
Low-level output current
I
OL
--
12
mA
V
CC
= 2.3 V
--
12
V
CC
= 2.7 V
--
24
V
CC
= 3.0 V
Input transition rise or fall rate
t/
v
0
10
ns/V
Operating free-air temperature
Ta
40
85
C
Note: Unused or floating control pins must be held high or low.
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