Members of the Texas Instruments
Widebus Family
Inputs Are TTL-Voltage Compatible
Independent Registers for A and B Buses
Multiplexed Real-Time and Stored Data
Flow-Through Architecture Optimizes
PCB Layout
Distributed VCC and GND Pin Configuration
Minimizes High-Speed Switching Noise
EPIC (Enhanced-Performance Implanted
CMOS) 1-
m Process
500-mA Typical Latch-Up Immunity at
125°C
Package Options Include Plastic 300-mil
Shrink Small-Outline (DL) Packages Using
25-mil Center-to-Center Pin Spacings and
380-mil Fine-Pitch Ceramic Flat (WD)
Packages Using 25-mil Center-to-Center
Pin Spacings

description
The ’ACT16646 are 16-bit bus transceivers
consisting of D-type flip-flops and control circuitry
with 3-state outputs arranged for multiplexed
transmission of data directly from the data bus or
from the internal storage registers. The devices
can be used as two 8-bit transceivers or one 16-bit
transceiver. 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 busmanagement
functions that can be performed
with the bus transceivers and registers.
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
controls (SAB and SBA) can multiplex stored and real-time (transparent mode) data. The circuitry used for
select control eliminates the typical decoding glitch that occurs in a multiplexer during the transition between
stored and real-time data. 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.
The 74ACT16646 is packaged in TI’s shrink small-outline package, which provides twice the functionality of
standard small-outline packages in the same printed-circuit-board area.
The 54ACT16646 is characterized for operation over the full military temperature range of –55°C to 125°C. The
74ACT16646 is characterized for operation from –40°C to 85°C.