SN54AS821

These 10-bit flip-flops feature 3-state outputs designed specifically for driving highly-capacitive or relatively low-impedance loads. SN54AS821 are particularly suitable for implementing wider buffer registers, I/O ports, bidirectional bus drivers with parity, and working registers.

The ten flip-flops are edge-triggered D-type flip-flops. On the positive transition of the clock the Q outputs on the SN54AS821 will be true, and on the 'AS822 will be complementary to the data input.

A buffered output-control input of SN54AS821 can be used to place the ten outputs in either a normal logic state (high or low levels) or a high-impedance state. In the high-impedance state, the outputs of SN54AS821 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 (OC) does not affect the internal operation of the flip-flops. Old data of SN54AS821 can be retained or new data can be entered while the outputs are in the high-impedance state.

The SN54AS821 family is characterized for operation over the full military temperature range of 55°C to 125°C. The SN74AS' family is characterized for operation from 0°C to 70°C.