SN54ALS29821 10-Bit Bus Interface Flip-Flops With 3-State Outputs |

SN54ALS29821 (ACTIVE) 10-Bit Bus Interface Flip-Flops With 3-State Outputs



These 10-bit edge-triggered D-type flip-flops feature 3-state outputs designed specifically for driving highly capacitive or relatively low-impedance loads. These devices are particularly suitable for implementing wider buffer registers, I/O ports, bidirectional bus drivers with parity, and working registers.

On the positive transition of the clock (CLK) input, the Q outputs are true to the data (D) input.

A buffered output-enable () input can place the ten outputs in either a normal logic state (high or low logic levels) or a high-impedance state. The outputs also are 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 bus lines without interface or pullup components.

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 SN54ALS29821 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALS29821 is characterized for operation from 0°C to 70°C.




  • Functionally Equivalent to AMD's AM29821
  • Provide Extra Data Width Necessary for Wider Address/Data Paths or Buses With Parity
  • Outputs Have Undershoot-Protection Circuitry
  • Power-Up High-Impedance State
  • Buffered Control Inputs Reduce dc Loading Effects
  • Package Options Include Plastic Small-Outline (DW) Packages and Standard Plastic (NT) and Ceramic (JT) 300-mil DIPs



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Part number Order Technology Family VCC (Min) (V) VCC (Max) (V) Bits (#) Voltage (Nom) (V) F @ nom voltage (Max) (MHz) ICC @ nom voltage (Max) (mA) tpd @ nom Voltage (Max) (ns) IOL (Max) (mA) IOH (Max) (mA) 3-state output Rating Operating temperature range (C)
SN54ALS29821 Order now ALS     4.75     5.25     10     5     75     15     10     48     -24     Yes     Military     -55 to 125    
SN74ALS29821 Samples not available ALS     4.75     5.25     10     5     75     115     10     48     -24     Yes     Catalog     0 to 70