Philips Semiconductors

Product specification

74ABT646A

Octal bus transceiver/register (3-State)

2

1998 Feb 17

853-1553 18978

FEATURES

and 200 V per Machine Model

DESCRIPTION

The 74ABT646A high-performance BiCMOS device combines low

static and dynamic power dissipation with high speed and high

output drive.

The 74ABT646A transceiver/register consists of bus transceiver

circuits with 3-State outputs, D-type flip-flops, and control circuitry

arranged for multiplexed transmission of data directly from the input

bus or the internal registers. Data on the A or B bus will be clocked

into the registers as the appropriate clock pin goes High. Output

Enable (OE) and DIR pins are provided to control the transceiver

function. In the transceiver mode, data present at the high

impedance port may be stored in either the A or B register or both.

The Select (SAB, SBA) pins determine whether data is stored or

transferred through the device in real-time. The DIR determines

which bus will receive data when the OE is active (Low). In the

isolation mode (OE = High), data from Bus A may be stored in the B

register and/or data from Bus B may be stored in the A register.

When an output function is disabled, the input function is still

enabled and may be used to store and transmit data. Only one of

the two buses, A or B, may be driven at a time. The examples on the

next page demonstrate the four fundamental bus management

functions that can be performed with the 74ABT646A.

QUICK REFERENCE DATA

SYMBOL

PARAMETER

CONDITIONS

TYPICAL

UNIT

Propagation delay

An to Bn or Bn to An

3.2

3.7

ns

Input capacitance

CP, S, OE, DIR

4

pF

I/O capacitance

Outputs disabled;

7

pF

Total supply current

110

µA

ORDERING INFORMATION

PACKAGES

TEMPERATURE RANGE

OUTSIDE NORTH AMERICA

NORTH AMERICA

DWG NUMBER

24-Pin Plastic DIP

–40

°C to +85°C

74ABT646A N

74ABT646A N

SOT222-1

24-Pin plastic SO

–40

°C to +85°C

74ABT646A D

74ABT646A D

SOT137-1

24-Pin Plastic SSOP Type II

–40

°C to +85°C

74ABT646A DB

74ABT646A DB

SOT340-1

24-Pin Plastic TSSOP Type I

–40

°C to +85°C

74ABT646A PW

7ABT646APW DH

SOT355-1

PIN CONFIGURATION

SA00082

CPAB

SAB

DIR

A0

A1

A2

A3

A4

A5

A6

A7

GND

1

2

3

4

5

6

7

8

9

10

11

12

CPBA

SBA

OE

B0

B1

B2

B3

B4

B5

B6

B7

13

14

15

16

17

18

19

20

21

22

23

24

PIN DESCRIPTION

PIN NUMBER

SYMBOL

FUNCTION

1, 23

CPAB /

CPBA

A to B clock input / B to A clock

input

2, 22

SAB / SBA

A to B select input / B to A

select input

3

DIR

Direction control input

4, 5, 6, 7,

8, 9, 10, 11

A0 – A7

Data inputs/outputs (A side)

20, 19, 18, 17,

16, 15, 14, 13

B0 – B7

Data inputs/outputs (B side)

21

OE

Output enable input

(active-Low)

12

GND

Ground (0V)

24

Positive supply voltage