Patent ID: 8659280

Claim:
A circuit for a switch mode power supply comprising: a transient detection portion comprising a resistor capacitor combination configured to delay an analogue error signal, the analogue error signal being derived from an output voltage of the switch mode power supply and a reference voltage and to detect whether a difference between the analogue error signal and the delayed analogue error signal is within a predetermined range, wherein the transient detection portion is further configured to determine if the delayed analogue error signal is smaller or larger than the analogue error signal, wherein the resistor capacitor combination includes a capacitor and a first resistor, wherein the transient detection portion further includes a second resistor and a third resistor, wherein the capacitor and the first resistor are directly connected to the second resistor and the third resistor, wherein the transient detection portion is further configured to generate the analogue error signal based on a difference between the output voltage of the switch mode power supply and a predetermined reference voltage, wherein the transient detection portion comprises: first and second comparators having their reference inputs connected to the second resistor and a node that is directly connected to the capacitor and the first, second and third resistors, respectively, and a third comparator having a reference input connected to the third resistor, wherein the first, second and third comparators are configured to receive first, second and third reference voltage levels determined with respect to the delayed analogue error signal, respectively, and wherein each of their second inputs is configured to directly receive the analogue error signal.