SN54ALS299

• Multiplexed I/O Ports Provide Improved Bit Density
• Four Modes of Operation:
  Hold (Store)
  Shift Right
  Shift Left
  Load Data
• Operate With Outputs Enabled or at High Impedance
• 3-State Outputs Drive Bus Lines Directly
• Can Be Cascaded for n-Bit Word Lengths
• Direct Overriding Clear
• Applications:
  Stacked or Push-Down Registers
  Buffer Storage
  Accumulator Registers
• Package Options Include Plastic Small-Outline (DW) Packages, Ceramic Chip Carriers (FK), and Standard Plastic (N) and Ceramic (J) 300-mil DIPs

Supply voltage, V_CC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  . . . . . . . . . . . . . 7 V
Input voltage, V_I: All inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
I/O ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 V
Operating free-air temperature range, T_A: SN54ALS299 . . . . . . . . . . . . . . 55°C to 125°C
                                                                   SN74ALS299 . . . . . . . .  . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65°C to 150°C

‡ Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

These 8-bit universal shift/storage registers SN54ALS299 feature multiplexed I/O ports to achieve full 8-bit data handling in a single 20-pin package. Two function-select (S0, S1) inputs and two outputenable (OE1, OE2) inputs of SN54ALS299 can be used to choose the modes of operation listed in the function table.

Synchronous parallel loading of SN54ALS299 is accomplished by taking both S0 and S1 high. This places the 3-state outputs in the high-impedance state and permits data applied on the I/O ports to be clocked into the register. Reading out of the register can be accomplished while the outputs of SN54ALS299 are enabled in any mode. Clearing occurs asynchronously when the clear (CLR) input is low. Taking either OE1 or OE2 high disables the outputs, but has no effect on clearing, shifting, or storing data.

The SN54ALS299 is characterized for operation over the full military temperature range of 55°C to 125°C. The SN74ALS299 is characterized for operation from 0°C to 70°C.