SN54AS821A

Features:

• 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 to Reduce dc Loading Effects
• Package Options Include Plastic Small-Outline (DW) Packages, Ceramic Chip Carriers (FK), and Standard Plastic (NT) and Ceramic (JT) 300-mil DIPs


Specifications

Supply voltage, VCC:7 V
Input voltage, VI :7 V
Voltage applied to a disabled 3-state output :5.5 V
Operating free-air temperature range, TA:SN54AS821A : 55°C to 125°C
                                                                  SN74AS821A :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.


Description

These 10-bit flip-flops feature 3-state outputs of SN54AS821A designed specifically for driving highly capacitive or relatively low-impedance loads. SN54AS821A is particularly suitable for implementing wider buffer registers, I/O ports, bidirectional bus drivers with parity, and working registers.
The ten flip-flops of SN54AS821A are edge-triggered D-type flip-flops. On the positive transition of the clock (CLK) input, the Q outputs are true to the data (D) input.
A buffered output-enable (OE) input of SN54AS821A can be used to place the ten outputs in either a normal logic state (high or low logic levels) or a highimpedance state. 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.
OE does not affect the internal operation of the flip-flops. Previously stored data of SN54AS821A can be retained or new data can be entered while the outputs are in the high-impedance state.
The SN54AS821A is characterized for operation over the full military temperature range of 55°C to 125°C. The SN74AS821A is characterized for operation from 0°C to 70°C.