SN74ALVTH16721

The SN74ALVTH16721 devices are 20-bit flip-flops with 3-state outputs designed for 2.5-V or 3.3-V V_CC operation, but with the capability to provide a TTL interface to a 5-V system environment. These SN74ALVTH16721 devices are particularly suitable for implementing buffer registers, I/O ports, bidirectional bus drivers, and working registers.On the positive transition of the clock (CLK), the flip-flops store the logic levels set up at the data (D) inputs.

A buffered output-enable (OE) input places the 20 outputs in either a normal logic state (high or low) or a high-impedance 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 need for interface or pullup components. OE 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. When V_CC is between 0 and 1.2 V, the device is in the high-impedance state during power up or power down. However, to ensure the high-impedance state above 1.2 V, OE should be tied to V_CC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver. Active bus-hold circuitry is provided to hold unused or floating data inputs at a valid logic level. The SN54ALVTH16721 is characterized for operation over the full military temperature range of 55°C to 125°C. The SN74ALVTH16721 is characterized for operation from 40°C to 85°C.