The UCD7K family of devices have a built-in handshaking feature to facilitate efficient start-up of the digitally controlled power supply. At start-up the CLF flag is held high until all the internal and external supply voltages of the UCD7K device are within their operating range. Once the supply voltages are within acceptable limits, the CLF goes low and the device will process input drive signals. The micro-controller should monitor the CLF flag at start-up and wait for the CLF flag to go LOW before sending power pulses to the UCD7K device.