Power converter
View Patent ↗A power converter comprises an inductor (L) and a main switch (M 1 ) having a main current path, the inductor (L) and the main current path are arranged in series to receive a DC-input voltage (VIN). A control circuit (CC) controls on-periods (Ton) and/or off-periods (Toff) of the main switch (M 1 ) to stabilize an output voltage (VO) supplied to a load (LO). The control circuit (CC) further has an input (IN) to receive a measuring signal (MS) to protect the main switch (M 1 ) against situations of overvoltage. A measuring circuit (MC) is coupled to a junction (J 1 ) of the inductor (L) and the main current path to obtain the measuring signal (MS) which is indicative of a voltage across the main current path. Preferably, the measuring circuit (MC) comprises a peak-clamp.
1. A power converter comprising: an inductor and a main switch having a main current path, the inductor sand the main current path being arranged in series for receiving a DC-input voltage, a measuring circuit coupled to a junction of the inductor and the main switch to obtain a measuring signal being indicative of a voltage across the main current path, and a control circuit for controlling on-periods and/or off-periods of the main switch to stabilize an output voltage supplied to a load, and having an input for receiving the measuring signal to protect the main switch against an overvoltage.
2. A power converter as claimed in claim 1 , wherein the measuring circuit comprises a series arrangement of a diode and a capacitors, the series arrangement of the diode and the capacitor being coupled in parallel with the inductor, the input of the control circuit being coupled to a junction of the series arrangement of the diode and the capacitors.
3. A power converter as claimed in claim 2 , wherein the diode is coupled to the junction of the main switch and the inductor, the diode being poled to be able to conduct during the off-period of the main switch.
4. A power converter as claimed in claim 3 , wherein the measuring circuit comprises a resistor coupled across the capacitor.
5. A power converter as claimed in claim 2 , wherein the measuring circuit comprises a resistor divider comprising a first resistor and a second resistor, the first resistor being coupled between the junction of the capacitor and the diode and the input of the control circuit, the second resistor being coupled between the input of the control circuit and a fixed potential.
6. A power converter as claimed in claim 5 , wherein the control circuit comprises: a series arrangement of a further switch and a current-to-voltage converter, the series arrangement being coupled between the input and a reference potential, a first comparator for comparing a voltage at the input with a first reference voltage when the further switch is open, and a second comparator for comparing a voltage at an output of the current to voltage converter with a second reference potential when the further switch is closed.
7. A power converter as claimed in claim 1 , wherein the control circuit comprises an comparator for comparing the measuring signal with a reference signal to halt the operation of the power converter when the measuring signal crosses the reference signal indicating that a voltage across the main switch is higher than a particular value.
8. A power converter as claimed in claim 1 , wherein the diode and the capacitor are dimensioned to operate as a peak-limiter.
9. An apparatus comprising the power converter as claimed in claim 1 .
10. An apparatus as claimed in claim 9 , wherein the apparatus comprises a processing circuit for processing an input signal into an output signal to be made audible via a sound transducer and/or to be displayed on a display device and the power converter as claimed in claim 1 , wherein the load comprises the processing circuit.
11. A control circuit for use in the power converter claim 1 .