Voltage regulator that can operate with or without an external power transistor

A voltage regulator comprising:

• an internal power transistor;
• an integrated circuit that contains internal components of the voltage regulator, the integrated circuit functions in a first configuration to produce an output voltage of the voltage regulator at a first desired output current level using the internal power transistor and a first frequency compensation scheme and functions in a second configuration to control an external power transistor to produce the output voltage of the voltage regulator at a second desired output current level with a second frequency compensation scheme;
• a first I/O node of the integrated circuit at which the integrated circuit receives a supply voltage in both the first and second configurations;
• a second I/O node of the integrated circuit at which the integrated circuit receives the supply voltage in the first configuration and which is connected to control the external power transistor in the second configuration;
• a third I/O node of the integrated circuit at which the integrated circuit produces the output voltage in the first configuration and at which the integrated circuit receives feedback of the output voltage in the second configuration;
• an internal sensor that determines whether the integrated circuit is in either the first configuration in which the external power transistor is not connected to the integrated circuit or the second configuration in which the external power transistor is connected to the integrated circuit by determining whether a voltage at the second I/O node is substantially less than a sense voltage based on the supply voltage from the first I/O node;
• an internal capacitor that contributes to the second frequency compensation scheme within the voltage regulator when it is determined in the second configuration that the external power transistor is connected to the integrated circuit;
• and
• an internal switch, activated and deactivated by the internal sensor, that prevents the capacitor from contributing to the first frequency compensation scheme when it is determined in the first configuration that the external power transistor is not connected to the integrated circuit and that enables the capacitor to contribute to the second frequency compensation scheme when it is determined in the second configuration that the external power transistor is connected to the integrated circuit.

A method of operating a voltage regulator comprising:

• powering on the voltage regulator that includes an internal capacitor;
• determining whether an external power transistor is connected to the voltage regulator;
• upon determining that the external power transistor is not connected to the voltage regulator, utilizing a first frequency compensation scheme by the voltage regulator that includes preventing the internal capacitor from contributing to frequency compensation by the voltage regulator;
• and
• upon determining that the external power transistor is connected to the voltage regulator, utilizing a second frequency compensation scheme by the voltage regulator that includes enabling the internal capacitor to contribute to the frequency compensation by the voltage regulator.