Voltage sensing mechanism to minimize short-to-ground current for low drop-out and bypass mode regulators

A method, comprising:

• operating a first power transistor in a low drop-out mode or in a bypass mode;
• operating a second power transistor in the bypass mode, wherein the second power transistor is in parallel with the first power transistor;
• and controlling, with a short to ground sensor, current to the first power transistor and to the second power transistor, wherein the controlling limits a maximum short-circuit current below a predefined load current capability of a load coupled to an output of the first power transistor and to an output of the second power transistor;
• wherein the controlling compares a reference voltage to a feedback voltage, with a voltage comparator, and wherein a first diode clamp having an input coupled to an output of logic circuitry of the short to ground sensor and an output coupled to a gate of the first power transistor configures the first power transistor to operate in the low drop-out mode when the comparison yields a result that the reference voltage is greater than the feedback voltage and the first diode clamp further configures the first power transistor to operate in the bypass mode when the comparison yields a result that the reference voltage is less than the feedback voltage and the short to ground sensor configures the second power transistor to operate in the bypass mode, wherein the low drop-out mode provides regulation of a voltage source provided to the load and the bypass mode does not provide regulation of the voltage source;
• such that in the bypass mode the voltage source is applied to the load without additional regulation of the voltage source;
• and wherein current flows through both the first power transistor and the second power transistor in parallel when the first power transistor and the second power transistor are configured to operate in the bypass mode.

An apparatus, comprising:

• means for operating a first power transistor;
• means for operating a second power transistor, wherein the second power transistor is in parallel with the first power transistor;
• and
• means for controlling, with a short to ground sensor, current to the first power transistor and to the second power transistor, wherein the controlling limits a maximum short-circuit current below a predefined load current capability of a load coupled to an output of the first power transistor and to an output of the second power transistor;
• wherein the means for controlling compares, with a voltage comparator, a reference voltage to a feedback voltage and configures, with a first diode clamp coupled to an output of logic circuitry of the short to ground sensor and to a gate of the first power transistor, wherein the first diode clamp configures the first power transistor to operate in a low drop-out mode when the comparison yields a result that the reference voltage is greater than the feedback voltage and the first diode clamp configures the first power transistor to operate in the bypass mode when the comparison yields a result that the reference voltage is less than the feedback voltage and the short to ground sensor configures the second power transistor to operate in the bypass mode, wherein the low drop-out mode provides regulation of a voltage source provided to the load and the bypass mode does not provide regulation of the voltage source, such that in the bypass mode the voltage source is applied to the load without additional regulation of the voltage source;
• and
• wherein current flows through both the first power transistor and the second power transistor in parallel when the first power transistor and the second power transistor are configured to operate in the bypass mode.