SN54HC646 Datasheet, PDF (1/10 Pages) Texas Instruments – OCTAL BUS TRANSCEIVERS AND REGISTERS WITH 3-STATE OUTPUTS

SN54HC646, SN74HC646
OCTAL BUS TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS
SCLS150B – DECEMBER 1982 – REVISED MAY 1997
D Independent Registers for A and B Buses
D Multiplexed Real-Time and Stored Data
D True Data Paths
D High-Current 3-State Outputs Can Drive up
to 15 LSTTL Loads
D Package Options Include Plastic
Small-Outline (DW) and Ceramic Flat (W)
Packages, Ceramic Chip Carriers (FK), and
Standard Plastic (NT) and Ceramic (JT)
300-mil DIPs
description
The ’HC646 consist 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 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 ’HC646.
Output-enable (OE) and direction-control (DIR)
inputs control the transceiver functions. In the
transceiver mode, data present at the
high-impedance port may be stored in either or
both registers.
The select-control (SAB and SBA) inputs can
multiplex stored and real-time (transparent mode)
data. DIR determines which bus receives data
when OE is active (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.
SN54HC646 . . . JT OR W PACKAGE
SN74HC646 . . . DW OR NT PACKAGE
(TOP VIEW)
CLKAB 1
SAB 2
DIR 3
A1 4
A2 5
A3 6
A4 7
A5 8
A6 9
A7 10
A8 11
GND 12
24 V_CC
23 CLKBA
22 SBA
21 OE
20 B1
19 B2
18 B3
17 B4
16 B5
15 B6
14 B7
13 B8
SN54HC646 . . . FK PACKAGE
(TOP VIEW)
4 3 2 1 28 27 26
A1 ₅
25 ^OE
A2 ₆
24 B1
A3 7
23 B2
NC 8
22 NC
A4 9
21 B3
A5 10
20 B4
A6 1112 _{13 14 15 16 17 1819} B5
NC – No internal connection
When an output function is disabled, the input function is still enabled and can be used to store and transmit
data. Only one of the two buses, A or B, may be driven at a time.
The SN54HC646 is characterized for operation over the full military temperature range of – 55°C to 125°C. The
SN74HC646 is characterized for operation from –40°C to 85°C.
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.
UNLESS OTHERWISE NOTED this document contains PRODUCTION
DATA information 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.
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Copyright © 1997, Texas Instruments Incorporated
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