SN54BCT646, SN74BCT646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCBS037D AUGUST 1989 REVISED MAY 2004
1
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
POST OFFICE BOX 1443
HOUSTON, TEXAS 772511443
D State-of-the-Art BiCMOS Design
Significantly Reduces ICCZ
D Bus Transceivers/Registers
D Independent Registers and Enables for
A and B Buses
D Multiplexed Real-Time and Stored Data
D ESD Protection Exceeds JESD 22
2000-V Human-Body Model (A114-A)
200-V Machine Model (A115-A)
CLKAB
SAB
DIR
A1
A2
A3
A4
A5
A6
A7
A8
GND
VCC
CLKBA
SBA
OE
B1
B2
B3
B4
B5
B6
B7
B8
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
SN54BCT646 ...JT OR W PACKAGE
SN74BCT646 . . . DW OR NT PACKAGE
(TOP VIEW)
5
6
7
8
9
10
11
25
24
23
22
21
20
19
432
1 28
12 13 14 15 16
OE
B1
B2
NC
B3
B4
B5
A1
A2
A3
NC
A4
A5
A6
SN54BCT646...FK PACKAGE
(TOP VIEW)
DIR
SAB
CLKAB
B8
B7
A8
GND
NC
CLKBA
SBA
V
A7
B6
17 18
27 26
CC
NC No internal connection
description/ordering information
These devices consist of bus transceiver circuits, D-type flip-flops, and control circuitry arranged for multiplexed
transmission of data directly from the input bus or from the internal registers. Data on the A or B bus is clocked
into the registers on the low-to-high transition of the appropriate clock (CLKAB or CLKBA) input. Figure 1
illustrates the four fundamental bus-management functions that can be performed with the ’BCT646 devices.
Output-enable (OE) and direction-control (DIR) inputs are provided to control the transceiver functions. In the
transceiver mode, data present at the high-impedance port can be stored in either register or in both.
The select-control (SAB and SBA) inputs can multiplex stored and real-time (transparent mode) data. The
direction control (DIR) determines which bus will receive data when OE is low. In the isolation mode (OE high),
A data can be stored in one register and/or B data can be stored in the other register.
ORDERING INFORMATION
TA
PACKAGE
ORDERABLE
PART NUMBER
TOP-SIDE
MARKING
PDIP NT
Tube
SN74BCT646NT
0
°C to 70°C
SOIC
DW
Tube
SN74BCT646DW
BCT646
0 C to 70 C
SOIC DW
Tape and reel
SN74BCT646DWR
BCT646
CDIP JT
Tube
SNJ54BCT646JT
55
°C to 125°C
CFP W
Tube
SNJ54BCT646W
LCCC FK
Tube
SNJ54BCT646FK
Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are
available at www.ti.com/sc/package.
Copyright
2004, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
On products compliant to MIL-PRF-38535, all parameters are tested
unless otherwise noted. On all other products, production
processing does not necessarily include testing of all parameters.