HD74ALVCH162270
12-bit to 24-bit Registered Bus Exchanger with 3-state Outputs
ADE-205-178A (Z)
2nd. Edition
March 1998
Description
The HD74ALVCH162270 is used in applications where data must be transferred from a narrow high speed
bus to a wide lower frequency bus. The device provides synchronous data exchange between the two ports.
Data is stored in the internal registers on the low to high transition of the clock (CLK) input when the
appropriate
CLKEN inputs are low. The select (SEL) line selects 1B or 2B data for the A outputs. For data
transfer in the A to B direction, a two stage pipeline is provided in the A to 1B path, with a single storage
register in the A to 2B path. Proper control of the
CLKENA inputs allows two sequential 12-bit words to
be presented synchronously as a 24-bit word on the B port. Data flow is controlled by the active low output
enables (
OEA, OEB). The control terminals are registered to synchronize the bus direction changes with
CLK. Active bus hold circuitry is provided to hold unused or floating data inputs at a valid logic level. All
outputs, which are designed to sink up to 12 mA, include 26
resistors to reduce overshoot and
undershoot.
Features
V
CC
= 2.3 V to 3.6 V
Typical V
OL
ground bounce < 0.8 V (@V
CC
= 3.3 V, Ta = 25C)
Typical V
OH
undershoot > 2.0 V (@V
CC
= 3.3 V, Ta = 25C)
High output current 12 mA (@V
CC
= 3.0 V)
Bus hold on data inputs eliminates the need for external pullup / pulldown resistors
All outputs have equivalent 26
series resistors, so no external resistors are required.
HD74ALVCH162270
5
Absolute Maximum Ratings
Item
Symbol
Ratings
Unit
Conditions
Supply voltage
V
CC
0.5 to 4.6
V
Input voltage
*1, 2
V
I
0.5 to 4.6
V
Except I/O ports
0.5 to V
CC
+0.5
I/O ports
Output voltage
*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
Tstg
65 to 150
C
Notes:
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
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
--
6
mA
V
CC
= 2.3 V
--
8
V
CC
= 2.7 V
--
12
V
CC
= 3.0 V
Low level output current
I
OL
--
6
mA
V
CC
= 2.3 V
--
8
V
CC
= 2.7 V
--
12
V
CC
= 3.0 V
Input transition rise or fall rate
t /
v
0
10
ns / V
Operating temperature
Ta
40
85
C
Note:
Unused control inputs must be held high or low to prevent them from floating.
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