Real-time short-circuit detection
View Patent ↗Presented are circuits and methods for providing real-time short-circuit detection, capable of detecting a short-circuit prior to occurrence of an over-limit current event. Such a circuit can be used to provide real-time short-circuit detection for a switched-mode system for a switched-mode system having a pre-driver and a power stage, and includes a reference block for generating a reference voltage according to drive signals provided by the pre-driver, and a comparator, which may be a synchronized comparator. The comparator is configured to compare the reference voltage to a switching node voltage generated in a power stage of the switched-mode system, and to produce an output enabling detection of the short-circuit in the switched-mode system.
1. A circuit for a switched-mode system having a pre-driver and a power stage, the circuit comprising:
a reference circuit configured to generate a reference voltage according to drive signals from the pre-driver and a replica load; and
a comparator circuit configured to compare the reference voltage to a switching node voltage generated by the power stage to generate and output indicative of a short-circuit in the switched-mode system,
wherein the comparator is a synchronized comparator, and the circuit further includes an adaptive clock to drive the synchronized comparator.
2. The circuit of claim 1 , wherein the adaptive clock is generated according to control signals that produce a difference between the reference voltage and the switching node voltage.
3. The circuit of claim 1 , wherein the circuit is configured to enable the detection of the short-circuit prior to an occurrence of an over-limit current event in the power stage.
4. The circuit of claim 1 , wherein the reference block comprises a scaled replica of the power stage.
5. The circuit of claim 1 , wherein the switched-mode system is one of a class-D audio amplifier and a switching regulator.
6. A switched-mode system comprising:
a power stage circuit including a switching node voltage;
a pre-driver circuit configured to produce drive signals; and
a circuit including:
a reference block circuit coupled between the pre-driver and the power stage and configured to generate a reference voltage according to the drive signals and a replica load;
a synchronized comparator circuit configured to compare the reference voltage to the switching node voltage of the power stage to produce an output indicative of a short-circuit load condition of the switched-mode system; and
an adaptive clock to drive the synchronized comparator.
7. The switched-mode system of claim 6 , wherein the adaptive clock is generated according to control signals that produce a difference between the reference voltage and the switching node voltage.
8. The switched-mode system of claim 6 , wherein the circuit is configured to enable the detection of the short-circuit load condition prior to an occurrence of an over-limit current event in the power stage.
9. The switched-mode system of claim 6 , wherein the reference block comprises a scaled replica of the power stage.
10. The switched-mode system of claim 6 , wherein the switched-mode system is a class-D audio amplifier.
11. The switched-mode system of claim 6 , wherein the switched-mode system is a switching regulator.
12. A method for use by a circuit in a switched-mode system, the method comprising:
receiving drive signals from a pre-driver circuit;
obtaining a switching node voltage generated by a power stage circuit;
generating, by a reference circuit, a reference voltage using the drive signals and a replica load;
comparing the reference voltage to the switching node voltage using a comparator circuit;
outputting, by the comparator, a signal indicative of a short-circuit in the switched-mode system; and
clocking the comparator using an adaptive clock.
13. The method of claim 12 , further comprising generating the adaptive clock according to control signals that produce a difference between the reference voltage and the switching node voltage.
14. The method of claim 12 , wherein the detecting occurs prior to an occurrence of an over-current event.
15. The method of claim 12 , wherein the switched-mode system is a class-D audio amplifier.
16. The method of claim 12 , wherein the switched-mode system is a switching regulator.