A Dynamic Output Control (DOC™) circuit is implemented, which, during the transition, initially lowers the output impedance to effectively drive the load and, subsequently, raises the impedance to reduce noise. Figure 1 shows typical V_OL vs I_OL and V_OH vs I_OH curves to illustrate the output impedance and drive capability of the circuit. At the beginning of the signal transition, the DOC circuit provides a maximum dynamic drive that is equivalent to a high-drive standard-output device. For more information, refer to the TI application reports, AVC Logic Family Technology and Applications, literature number SCEA006, and Dynamic Output Control (DOC™) Circuitry Technology and Applications, literature number SCEA009.

This 18-bit universal bus driver is operational at 1.2-V to 3.6-V V_CC, but is designed specifically for 1.65-V to 3.6-V V_CC operation.

Data flow from A to Y is controlled by the output-enable (OE)\ input. The device operates in the transparent mode when the latch-enable (LE)\ input is low. The A data is latched if the clock (CLK) input is held at a high or low logic level. If LE\ is high, the A data is stored in the latch/flip-flop on the low-to-high transition of CLK. When OE\ is high, the outputs are in the high-impedance state.

To ensure the high-impedance state during power up or power down, 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.

This device is fully specified for partial-power-down applications using I_off. The I_off circuitry disables the outputs, preventing damaging current backflow through the device when it is powered down.