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.