54ACT16821, 74ACT16821
20-BIT BUS-INTERFACE FLIP-FLOPS
WITH 3-STATE OUTPUTS

SCAS176A - JANUARY 1991 - REVISED APRIL 1996

features

• Members of the Texas Instruments Widebus^TM Family
• Inputs Are TTL-Voltage Compatible
• Provide Extra Data Width Necessary for Wider Address/Data Paths or Buses With Parity
• 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
• Package Options Include 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

These 20-bit flip-flops feature 3-state outputs designed specifically for driving highly-capacitive or relatively low-impedance loads. They are particularly suitable for implementing wider buffer registers, I/O ports, parity bus interfacing, and working registers.

The 'ACT16821 can be used as two 10-bit flip-flops or one 20-bit flip-flop. On the positive transition of the clock (CLK) input, the Q outputs follow the data (D) inputs. Each 10-bit flip-flop section has a buffered output-enable (1 or 2) input that can be used to place the ten outputs in either a normal logic state (high or low logic levels) or the high-impedance state. In the high-impedance state, the outputs neither load nor drive the bus lines significantly.

does not affect the internal operation of the flip-flops. Old data can be retained or new data can be entered while the outputs are in the high-impedance state.

The 74ACT16821 is packaged in theTI 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 54ACT16821 is characterized for operation over the full military temperature range of -55°C to 125°C. The 74ACT16821 is characterized for operation from -40°C to 85°C.