Apparatus and method for device power-up using counter-enabled drivers

The secondary power supply Vbb which powers components on a semiconductor device receives power from a distributed primary power supply Vbb. During the power-up portion for the secondary power supply Vbb, a main driver amplifier 13 provides the power. After the secondary power supply Vbb has reached the desired voltage level, a standby driver amplifier 14 is used to maintain the desired voltage level. In the present invention, the main driver amplifier 13 is activated by a time base unit 21, 22 time in response activation of the primary power supply. The time base unit 21, 22 can simultaneously inactivate the standby driver amplifier 14, or the standby power supply can operate independently of the main driver amplifier 13. After a time interval sufficient to insure that the output from the secondary power supply has reached the desired voltage level, the main driver amplifier 13 is inactivated and the standby (i.e., lower power) amplifier provides the steady state power. In the preferred embodiment, the time base unit 21, 22 is implemented by an oscillator unit 21 and an oscillator counter unit 22, a predetermined number of oscillator signals determining the time interval.