54ACT16648, 74ACT16648
16-BIT TRANSCEIVERS AND REGISTERS
WITH 3-STATE OUTPUTS

SCAS188A - MAY 1991 - REVISED APRIL 1996

Copyright © 1996, Texas Instruments Incorporated

features

• Members of the Texas Instruments Widebus^TM Family
• Inputs Are TTL-Voltage Compatible
• Independent Registers for A and B Buses
• Inverting Data Path
• Multiplexed Real-Time and Stored Data
• Flow-Through Architecture Optimizes PCB Layout
• Distributed V_CC and GND Pin Configuration Minimizes High-Speed Switching Noise
• EPIC^TM (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

EPIC and Widebus are trademarks of Texas Instruments Incorporated.

description

The 'ACT16648 are 16-bit bus transceivers that consist of D-type flip-flops and control circuitry 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 bus-management functions that can be performed with the 74ACT16648.

Output-enable () 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 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 is low. In the isolation mode ( high), A data can be stored in one register and/or B data can be stored in the other register.

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, can be driven at a time.

The 74ACT16648 is packaged in TI's shrink small-outline package, which provides twice the I/O pin count and functionality of standard small-outline packages in the same printed-circuit-board area.

The 54ACT16648 is characterized for operation over the full military temperature range of -55°C to 125°C. The 74ACT16648 is characterized for operation from -40°C to 85°C.