Voltage sensing mechanism to minimize short-to-ground current for low drop-out and bypass mode regulators
View Patent ↗Various electronics systems may benefit from appropriate limitation of short-to-ground current. For example, sensor systems may benefit from a voltage sensing mechanism to minimize short-to-ground current for low drop-out and bypass mode regulators. A system can include a first power transistor configured to operate in a low drop-out mode. The system can also include a short to ground sensor configured to control current to the first power transistor. The short to ground sensor can be configured to limit a maximum short-circuit current below a predefined load current capability.
1. An apparatus, comprising: a first power transistor; a second power transistor, wherein the second power transistor is in parallel with the first power transistor; and a short to ground sensor configured to control current to the first power transistor and to the second power transistor, wherein the short to ground sensor is configured to limit 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 short to ground sensor comprises a voltage comparator to compare a reference voltage to a feedback voltage; a first diode clamp having an output coupled to a gate of the first power transistor; wherein the short to ground sensor further comprises logic circuitry having an output coupled to an input of the first diode clamp, wherein the first power transistor is configured by the first diode clamp 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 power transistor is configured by the first diode clamp to operate in a bypass mode when the comparison yields a result that the reference voltage is less than the feedback voltage, and wherein the second power transistor is configured by the short to ground sensor 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.
2. The apparatus of claim 1 , wherein the short to ground sensor is configured to affect the operation of the first diode clamp by selectively switching between use and non-use of the first diode clamp.
3. The apparatus of claim 1 , wherein the apparatus comprises a second diode clamp connected in series with the first diode clamp.
4. The apparatus of claim 3 , wherein, when the comparison yields the result that the reference voltage is greater than the feedback voltage, the short to ground sensor is further configured to limit the maximum short-circuit current using the second diode clamp; and wherein, when the comparison yields a result that the reference voltage is less than the feedback voltage, the short to ground sensor is further configured to limit the maximum short-circuit current using the first and second diode clamps.
5. The apparatus of claim 1 , further comprising:
a bypass controller configured to control operation of the first power transistor, wherein the short to ground sensor is configured to control use of the bypass controller.
6. The apparatus of claim 1 , wherein the short to ground sensor is configured to operate based on a voltage sensing mechanism measuring a voltage output at the first power transistor and the second power transistor.
7. 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.
8. The method of claim 7 , wherein the controlling operates based on a voltage sensing mechanism measuring a voltage output at the first power transistor and the second power transistor.
9. The method of claim 7 , wherein when the comparison yields a result that the reference voltage is greater than the feedback voltage, the controlling comprises limiting current using a second diode clamp.
10. The method of claim 7 , wherein when the comparison yields a result that the reference voltage is less than the feedback voltage, the controlling comprises limiting current using the first diode clamp and a second diode clamp connected in series with the first diode clamp.
11. The method of claim 10 , wherein the controlling comprises selectively switching between use and non-use of at least one of the first diode clamp and the second diode clamp.
12. The method of claim 7 , wherein the controlling comprises limiting the current to a selected one of two different current levels.
13. 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.
14. The apparatus of claim 13 , wherein the means for controlling comprises limiting the maximum short-circuit current to a selected one of two different current levels.
15. The apparatus of claim 13 , wherein when the comparison yields the result that the reference voltage is greater than the feedback voltage, the means for controlling comprises means for limiting current to a first level.
16. The apparatus of claim 13 , wherein when the comparison yields the result that the reference voltage is less than the feedback voltage, the means for controlling comprises means for limiting current to a second level different from a first level.
17. The apparatus of claim 13 , wherein the controlling limits the maximum short-circuit current below the predefined load current capability using the first diode clamp, and wherein the means for controlling comprises means for selectively switching between use and non-use of the first diode clamp.
18. The apparatus of claim 13 , wherein the means for controlling comprises means for limiting the maximum short-circuit current to a selected one of two different current levels.