Rectifier device with safety threshold

A rectifier device comprising:

• a semiconductor substrate;
• a plurality of transistor cells arranged in the semiconductor substrate;
• a first MOS transistor composed of at least a portion of the plurality of transistor cells, the first MOS transistor having a load current path and body diode coupled parallel to the load current path;
• an anode terminal and a cathode terminal connected by the load current path of the first MOS transistor and the body diode;
• and
• a control circuit comprising:
• a control logic that is configured to switch on the first MOS transistor upon detection that a voltage between cathode and anode terminal reaches a first threshold voltage and further configured to switch off the first MOS transistor upon detection that the voltage between cathode and anode terminal reaches a second threshold voltage, wherein the anode terminal has an electric potential that serves as ground potential for the control logic, and wherein the first and the second threshold voltages are negative;
• and
• a safety circuit that is configured to trigger a switch-off of the first MOS transistor when the voltage between cathode and anode terminal reaches a safety threshold, which is a positive threshold voltage.

A method for operating a rectifier device that comprises a MOS transistor and a diode coupled in parallel between an anode terminal and a cathode terminal, the method comprising:

• detecting that the diode is forward biased;
• switching on, by a control circuit, the MOS transistor upon detection that the diode is forward biased;
• detecting, while the diode is forward biased, that a voltage across the rectifier device between the cathode terminal and the anode terminal reaches a specific threshold voltage, wherein the detection that the voltage across the rectifier device has reached the specific threshold value is masked during a masking time following the switch-on of the MOS transistor;
• switching off the MOS transistor upon detection that the voltage across the rectifier device has reached the specific threshold value;
• detecting that a voltage between cathode and anode terminal rises above a safety threshold, wherein the detection that the safety threshold has been hit is effective during the masking time;
• and
• switching off, by the control circuit, the MOS transistor upon detection that the safety threshold has been hit.

A rectifier device comprising:

• an anode terminal and a cathode terminal connected by a first load current path of a first MOS transistor, a second load current path of a second MOS transistor connected in parallel to the first load current path of the first MOS transistor, and a diode connected parallel to the load current path;
• an alternating input voltage is operably applied between the anode terminal and the cathode terminal;
• the electrical potential at the anode terminal serving as reference potential for the rectifier device;
• and
• a control circuit comprising:
• control logic configured to switch on the first MOS transistor for an on-time period, during which the diode is forward biased;
• a safety circuit configured to trigger a switch-off of the first MOS transistor when the input voltage reaches a safety threshold;
• and
• at least one comparator circuit configured to compare a voltage at the cathode terminal with at least one threshold voltage;
• wherein the comparator receives, as a first input signal, a level-shifted and scaled representation of the voltage at the cathode terminal, and uses, as a second input signal, a level shifted and a scaled version of the at least one threshold voltage.

A rectifier device comprising:

• an anode terminal and a cathode terminal connected by a load current path of a first MOS transistor and a diode connected parallel to the load current path;
• an alternating input voltage is operably applied between the anode terminal and the cathode terminal;
• and
• a control circuit comprising:
• control logic configured to:
• switch on the first MOS transistor for an on-time period, during which the diode is forward biased, wherein an electrical potential at the anode terminal serves as reference potential for the control logic;
• and
• detect a beginning of the on-time period when the input voltage falls below a first threshold voltage that is negative with respect to the reference potential;
• and
• a safety circuit configured to trigger a switch-off of the first MOS transistor when the input voltage reaches a safety threshold.

A rectifier device comprising:

• an anode terminal and a cathode terminal connected by a load current path of a first MOS transistor and a diode connected parallel to the load current path;
• an alternating input voltage is operably applied between the anode terminal and the cathode terminal;
• and
• a control circuit comprising:
• control logic configured to:
• switch on the first MOS transistor for an on-time period, during which the diode is forward biased, wherein an electrical potential at the anode terminal serves as reference potential for the control logic;
• detect a beginning of the on-time period when the input voltage falls below a first threshold voltage that is negative with respect to the reference potential;
• and
• detect an ending of the on-time period when the input voltage reaches a second threshold voltage that is also negative with respect to the reference potential;
• and
• a safety circuit configured to trigger a switch-off of the first MOS transistor when the input voltage reaches a safety threshold.

A method for operating a rectifier device that comprises a MOS transistor and a diode coupled in parallel between an anode terminal and a cathode terminal, the method comprising:

• generating an internal supply voltage for a control circuit based on a voltage across the rectifier device between the cathode terminal and the anode terminal, wherein an electric potential at the anode terminal is used as ground potential for the control circuit;
• detecting that the diode is forward biased;
• switching on, by a control circuit, the MOS transistor upon detection that the diode is forward biased;
• detecting, while the diode is forward biased, that the voltage across the rectifier device between the cathode terminal and the anode terminal reaches a specific threshold voltage;
• switching off the MOS transistor upon detection that the voltage across the rectifier device has reached the specific threshold value;
• detecting that a voltage between cathode and anode terminal rises above a safety threshold;
• and
• switching off, by the control circuit, the MOS transistor upon detection that the safety threshold has been hit.

A method for operating a rectifier device that comprises a first MOS transistor, a diode coupled in parallel between an anode terminal and a cathode terminal, a further MOS transistor coupled in parallel to the diode between the anode terminal and the cathode terminal, the method comprising:

• detecting that the diode is forward biased;
• switching on, by a control circuit, the first MOS transistor upon detection that the diode is forward biased;
• switching on, by the control circuit, the further MOS transistor upon detection that the diode is forward biased;
• detecting, while the diode is forward biased, that a voltage across the rectifier device between the cathode terminal and the anode terminal reaches a specific threshold voltage;
• switching off the MOS transistor upon detection that the voltage across the rectifier device has reached the specific threshold value;
• detecting, after the first MOS transistor has been switched off, that the voltage across the rectifier device between the cathode terminal and the anode terminal reaches a specific further threshold voltage;
• detecting that a voltage between cathode and anode terminal rises above a safety threshold;
• switching off, by the control circuit, the first MOS transistor upon detection that the safety threshold has been hit;
• and
• switching off the further MOS transistor upon detection that the voltage across the rectifier device has reached the specific further threshold value.