HIT HD74ALVCHR162269A Datasheet

HD74ALVCHR162269A

12-bit to 24-bit Registered Bus Exchanger with 3-state Outputs

ADE-205-125 (Z)

Preliminary

1st. Edition

January 1998

Description

The HD74ALVCHR162269A is a 12-bit to 24-bit registered bus exchanger, which is intended for
applications where two separate ports must be multiplexed onto, or de-multiplexed from, a single port. It is
particularly suitable as an interface between synchronous DRAMs and high speed microprocessors. The
HD74ALVCHR162269A is designed specifically for low voltage (from 2.5 V to 3.3 V) VCC operation.

Data is stored in the internal B-port registers on the low to high transition of the CLK input, provided that
the appropriate CLKENA inputs are low. Proper control of these inputs allows two sequential 12-bit words
to be presented as a 24-bit word on the B-port. For data transfer in the B to A direction, a single storage
register is provided. The SEL line selects 1B or 2B data for the A outputs.

The register on the A output permits the fastest possible data transfer, thus extending the period that the
data will be valid on the bus. The control pins are registered so that all transactions are synchronous with
the clock. Data flows is controlled by the active low output enables (OEA, OEB1, OEB2).

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 Ω resistors to reduce overshoot and

undershoot.

Features

• All outputs have equivalent 26 Ω series resistors, so no external resistors are required.

• Bus hold on data inputs eliminates the need for external pullup / pulldown resistors.

HD74ALVCHR162269A

Function Table

Inputs Outputs
CLK OEA OEB A 1B, 2B

↑ HHZ Z
↑ H L Z Active
↑ L H Active Z

Output-enable table

Inputs Outputs
CLKENA1 CLKENA2 CLK A 1B 2B

LH↑LL 2B
LH↑HH 2B
LL↑LL L
LL↑HH H
HL↑L1B
HL↑H1B
HHXX1B

*1

0

*1

0

*1

0

A-to-B storage table (OEB = L)

*1

0

*1

0

L
H

*1

2B0

Inputs
CLK SEL 1B 2B Output A

XHXX A
XLXX A

*1

0

*1

0

↑ HLX L
↑ HHX H
↑ LXL L

B-to-A storage (OEA = L)

H : High level
L : Low level
X : Immaterial
Z : High impedance
↑ : Low to high transition
Note: 1. Output level before the indicated steady state input conditions were established.

2

Pin Arrangement

HD74ALVCHR162269A

OEA

OEB1

2B3

GND

2B2
2B1

V

CC

A1
A2
A3

GND

A4
A5
A6
A7
A8
A9

GND

A10
A11

A12

V

CC

1B1
1B2

GND

1B3

NC

SEL

10
11

12
13
14
15
16
17
18
19

20
21
22
23
24
25
26
27
28

56

1
2

3
4
5

6
7

8

9

OEB2
CLKENA2

55
54

2B4

53

GND
2B5

52
51

2B6

50

V

2B7

49

2B8

48
47

2B9

46

GND
2B10

45

2B11

44
43

2B12

42

1B12
1B11

41

1B10

40
39

GND

38

1B9
1B8

37

1B7

36

V

35
34

1B6

33

1B5

32

GND

31

1B4

30

CLKENA1

29

CLK

CC

CC

(Top view)

3

HD74ALVCHR162269A

Absolute Maximum Ratings

Item Symbol Ratings Unit Conditions

Supply voltage range V
Input voltage range

Output voltage range

*1, 2

*1, 2

Input clamp current I
Output clamp current I
Continuous output current I
Continuous current through ICC / I
Maximum power dissipation

at Ta = 55°C (in still air)

*3

CC

V

I

V

O

IK

OK

O

GND

P

T

Storage temperature range 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 power dissipation is calculated using a junction temperature of 150°C and board
trace length of 750 mils.

–0.5 to 4.6 V
–0.5 to 4.6 V Except I/O ports
–0.5 to VCC +0.5 I/O ports
–0.5 to VCC +0.5 V
–50 mA VI < 0

±50 mA VO < 0 or VO > V
±50 mA VO = 0 to V

CC

±100 mA
1 W TSSOP

CC

Recommended Operating Conditions

Item Symbol Min Max Unit Conditions

Supply voltage V
Input voltage V
Output voltage V
High-level output current I

Low-level output current I

CC

I

O

OH

OL

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.

4

2.3 3.6 V
0VCCV
0VCCV
—–6mAV
—–8 V

= 2.3 V

CC

= 2.7 V

CC

— –12 VCC = 3.0 V
— 6 mA VCC = 2.3 V
—8 V
—12 V

= 2.7 V

CC

= 3.0 V

CC