SN54LVT646, SN74LVT646
3.3-V ABT OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCBS140D – MAY 1992 – REVISED JULY 1995
SN54LVT646 . . . JT OR W PACKAGE
SN74LVT646 . . . DB, DW, OR PW PACKAGE
(TOP VIEW)
State-of-the-Art Advanced BiCMOS
Technology (ABT) Design for 3.3-V
Operation and Low Static Power
Dissipation
CLKAB
SAB
DIR
A1
V
CC
1
24
23
22
21
20
19
18
17
16
15
14
13
Support Mixed-Mode Signal Operation (5-V
Input and Output Voltages With 3.3-V V
CLKBA
SBA
OE
B1
2
)
CC
3
Support Unregulated Battery Operation
Down to 2.7 V
4
A2
5
A3
B2
6
Typical V
< 0.8 V at V
(Output Ground Bounce)
OLP
A4
B3
7
= 3.3 V, T = 25°C
CC
A
A5
B4
8
ESD Protection Exceeds 2000 V Per
MIL-STD-883C, Method 3015; Exceeds
200 V Using Machine Model
(C = 200 pF, R = 0)
A6
B5
9
A7
A8
GND
B6
B7
B8
10
11
12
Latch-Up Performance Exceeds 500 mA
Per JEDEC Standard JESD-17
SN54LVT646 . . . FK PACKAGE
(TOP VIEW)
Bus-Hold Data Inputs Eliminate the Need
for External Pullup Resistors
Support Live Insertion
Package Options Include Plastic
Small-Outline (DW), Shrink Small-Outline
(DB), and and Thin Shrink Small-Outline
(PW) Packages, Ceramic Chip Carriers
(FK), Ceramic Flat (W) Packages, and
Ceramic (JT) DIPs
4
3
2
1
28 27 26
25
OE
B1
B2
NC
A1
A2
A3
NC
A4
A5
A6
5
24
23
22
6
7
8
21 B3
9
description
20
19
10
11
B4
B5
These bus transceivers and registers are
designed specifically for low-voltage (3.3-V) V
12 13 14 15 16 17 18
CC
operation, but with the capability to provide a TTL
interface to a 5-V system environment.
NC – No internal connection
The ’LVT646 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 ′LVT646.
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 may 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 receives data when OE is low. In the isolation mode (OE high),
A data may be stored in one register and/or B data may be stored in the other 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.
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.
Copyright 1995, 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.
1
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