Method and apparatus to select a parameter/mode based on a time measurement

摘要

An example integrated control circuit includes a regulator, a first comparator, a second comparator, and a counter. The regulator is to charge, during a time period, a capacitor. The first comparator is to provide an output indicating when a voltage on the capacitor reaches a first threshold voltage. The second comparator is coupled to provide an output indicating when the voltage on the capacitor reaches a second threshold voltage. The counter is coupled to begin counting in response to the first threshold voltage being reached and is coupled to stop counting in response to the second threshold voltage being reached. The counter is coupled to provide an output representative of the capacitance value of the capacitor during the time period and the integrated control circuit receives a bias current at the terminal from the capacitor to provide power to operate the integrated control circuit after the time period has ended.

主权项

1. An integrated control circuit having an initialization time period at start-up of the integrated control circuit and a subsequent period of normal operation, the integrated control circuit comprising:
a regulator coupled to a first terminal to charge, during the initialization time period, a capacitor that is to be coupled to the first terminal; a first comparator coupled to the first terminal and coupled to provide an output indicating when a voltage on the capacitor reaches a first threshold voltage; a second comparator coupled to the first terminal and coupled to provide an output indicating when the voltage on the capacitor reaches a second threshold voltage; a counter coupled to begin counting in response to the output of the first comparator indicating that the first threshold voltage has been reached and to stop counting in response to the output of the second comparator indicating that the second threshold voltage has been reached, wherein the counter is coupled to provide an output representative of the capacitance value of the capacitor during the initialization time period, and wherein the integrated control circuit receives a bias current at the first terminal from the capacitor to provide power to operate the integrated control circuit after the initialization time period has ended and during the period of normal operation; and a drive signal generator to be coupled to control switching of a switch included in a power supply in response to a feedback signal to regulate a transfer of energy from an input of the power supply to an output of the power supply, wherein drive signal generator includes a first logic gate coupled to generate a drive signal to control the switching of the switch, wherein the first logic gate is enabled to provide the drive signal in response to an undervoltage signal indicating that the voltage on the capacitor has reached the second threshold voltage.