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US 6,784,645 B2Granted
Step-down converter
AssigneeSiemens Aktiengesellschaft
InventorKarl Formanek
Life of this patent
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Abstract
A step-down converter includes a self-conducting switching transistor (T1) and an inductance (L) located in a series arm, and a freewheeling diode (DF) located in a shunt arm. The switching transistor (T1) is controlled by a control transistor (T2). The control transistor supplies a blocking voltage, which is generated by a Zener diode (D1) in the series arm, to the switching transistor (T1) once a maximum value for a current (IL) in the series arm has been reached.
Claims6
A step-down converter for converting a DC input voltage into a DC output voltage, comprising:
- a series arm, comprising:
- a controlled switch having a self-conducting switching transistor;
- an inductance series-connected to the controlled switch;
- a first Zener diode;
- and
- a current sensor configured to sense a current flowing through the series arm;
- a shunt arm arranged between the controlled switch and the inductance, the shunt arm comprising a freewheeling diode;
- a capacitor parallel-connected to the first Zener diode;
- a smoothing capacitor arranged at an output of the step-down converter;
- and
- a control circuit having a control transistor, wherein the control transistor is configured to periodically open and close the controlled switch as a function of the current;
- and
- wherein the first Zener diode and the capacitor parallel-connected to the first Zener diode are configured to generate a blocking voltage, which is supplied to the self-conducting switching transistor when the current sensor senses at least a pre-determined maximum value of the current.
10 more elements
Dependencies are inferred from the claim text.