SN54ALS29843, SN74ALS29843, SN74ALS29844
9BIT BUS INTERFACE DTYPE LATCHES
WITH 3STATE OUTPUTS

SDAS151A – D2910 — JUNE 1988 — REVISED JANUARY 1990

features

• 3-State Buffer-Type Outputs Drive Bus Lines Directly
• Bus-Structured Pinout
• Provide Extra Bus Driving Latches Necessary For Wider Address/Data Paths or Buses With Parity
• Buffered Control Inputs to Reduce DC Loading
• Power-Up High-Impedance
• Package Options Include Plastic "Small Outline" Packages and Standard Plastic and Ceramic 300-Mil DIPs

description

These 9-bit latches feature three-state outputs designed specifically for driving highly capacitive or relatively low-impedance loads. They are particularly suitable for implementing buffer registers, I/O ports, bidirectional bus drivers, and working registers.

The nine latches are transparent D-type. The ´ALS29843 has noninverting data (D) inputs. The ´ALS29844 has inverting D\ inputs.

A buffered output control () input can be used to place the nine outputs in either a normal logic state (high or low levels) or a high-impedance state. The outputs are also in the high-impedance state during power-up and power-down conditions. The outputs remain in the high-impedance state while the device is powered-down. In the high-impedance state, the outputs neither load nor drive the bus lines significantly. The high-impedance state and increased drive provide the capability to drive the bus lines in a bus-organized system without need for interface or pullup components.

The output control () does not affect the internal operation of the latches. Old data can be retained or new data can be entered while the outputs are off.

The SN54ALS29843 is characterized for operation over the full military range of - 55°C to 125°C. The SN74ALS29843 and SN74ALS29844 are characterized for operation from 0°C to 70°C.