54AC16821,74AC16821
WITH 3STATE OUTPUTS

features

• Members of the Texas Instruments Widebus^TM Family
• Packaged in Shrink Small-Outline 300-mil Packages (DL) and 380-mil Fine-Pitch Ceramic Flat Packages Using 25-mil Center-to-Center Pin Spacings
• Provides Extra Data Width Necessary for Wider Address/Data Paths or Buses with Parity
• Flow-Through Architecture to Optimize Printed-Circuit-Board (PCB) Layout
• Distributed V_CC and GND Pin Configuration to Minimize High-Speed Switching Noise
• EPIC^TM (Enhanced-Performance Implanted CMOS) 1-m Process
• 500-mA Typical Latch-Up Immunity at 125°C

description

These 20-bit flip-flops feature three-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, bidirectional bus drivers with parity, and working registers.

These devices can be used as two 10-bit flip-flops or one 20-bit flip-flop.

On the positive transition of the clock the Q outputs will follow the D inputs. A buffered output enable () input can be used to place the twenty outputs in either a normal logic state (high or low) or a high-impedance state. In the high-impedance state the outputs neither load nor drive the bus lines significantly. The output enable () 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 74AC16821 is packaged in TI's shrink small-outline package (DL), which provides twice the I/O pin count and functionality of standard small-outline packages in the same printed-circuit-board area.

The 54AC16821 is characterized over the full military temperature range of -55°C to 125°C. The 74AC16821 is characterized for operation from -40°C to 85°C.