The UCD7K devices accept an input range of 4.5 V to 15 V. The device has an internal precision linear regulator that produces the 3V3 output from this VDD input. A separate pin, PVDD, not connected internally to the VDD supply rail provides power for the output drivers. In all applications the same bus voltage supplies the two pins. It is recommended that a low value of resistance be placed between the two pins so that the local capacitance on each pin forms low pass filters to attenuate any switching noise that may be on the bus.

Although quiescent VDD current is low, total supply current will be higher, depending on the gate drive output current required by the switching frequency. Total V_DD current is the sum of quiescent V_DD current and the average OUT current. Knowing the operating frequency and the MOSFET gate charge (Q_G), average OUT current can be calculated from:

I_OUT = Q_G x f, where f is frequency.

For high-speed circuit performance, a V_DD bypass capacitor is recommended to prevent noise problems. A 4.7-µF ceramic capacitor should be located close to the V_DD to ground connection. A larger capacitor with relatively low ESR should be connected to the PVDD pin, to help deliver the high current peaks to the load. The capacitors should present a low impedance characteristic for the expected current levels in the driver application. The use of surface mount components for all bypass capacitors is highly recommended.