Insulated synchronous rectification dc/dc converter
AssigneeRohm Co., Ltd.
InventorHiroki KIKUCHI
Life of this patent
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Abstract
A synchronous rectification controller configured to control a synchronous rectification transistor is provided on the secondary side of an insulated synchronous rectification DC/DC converter. A DRAIN pin receives the drain voltage VDS2 of the synchronous rectification transistor. A pulse generator generates a pulse signal S11 based on the voltage at the DRAIN pin. A driver drives the synchronous rectification transistor based on the pulse signal S11. Upon detecting an open-circuit fault of the DRAIN pin, an abnormality detection circuit asserts an abnormality detection signal S13.
Claims39
A synchronous rectification controller structured to control a synchronous rectification transistor of an insulated synchronous rectification DC/DC converter, the synchronous rectification controller comprising:
- a drain pin structured to receive a drain voltage of the synchronous rectification transistor;
- a pulse generator structured to generate a pulse signal based on a voltage at the drain pin;
- a driver structured to drive the synchronous rectification transistor based on the pulse signal;
- and
- an abnormality detection circuit structured to assert an abnormality detection signal when an open-circuit fault of the drain pin is detected.
An insulated synchronous rectification DC/DC converter comprising:
- a transformer comprising a primary winding and a secondary winding;
- a switching transistor coupled to the primary winding of the transformer;
- a synchronous rectification transistor coupled to the secondary winding of the transformer;
- a photocoupler comprising a light-emitting element and a light-receiving element;
- a feedback circuit structured to drive the light-emitting element of the photocoupler such that an output voltage of the DC/DC converter approaches a target voltage;
- a primary controller coupled to the light-receiving element and structured to perform switching of a switching transistor according to a feedback signal received from the light-receiving element;
- and
- a synchronous rectification controller comprising a drain pin coupled to a drain of the synchronous rectification transistor and structured to drive the synchronous rectification transistor based on a voltage at the drain pin,
- and wherein, upon detecting an open-circuit fault of the drain pin, the synchronous rectification controller suspends the switching of the switching transistor controlled by the primary controller.
An insulated synchronous rectification DC/DC converter comprising:
- a transformer comprising a primary winding and a secondary winding;
- a switching transistor coupled to the primary winding of the transformer;
- a synchronous rectification transistor coupled to the secondary winding of the transformer;
- a photocoupler comprising a light-emitting element and a light-receiving element;
- a feedback circuit structured to drive the light-emitting element of the photocoupler such that a detection voltage that corresponds to an output voltage of the DC/DC converter approaches a target voltage;
- a primary controller coupled to the light-receiving element of the photocoupler, and structured to perform switching of a switching transistor according to a feedback signal received from the light-receiving element;
- a synchronous rectification controller structured to drive the synchronous rectification transistor;
- and
- a first protection circuit structured to maintain a driving state of the light emitting element upon detecting an abnormality,
- wherein an auxiliary power supply voltage to be supplied to at least a part of the first protection circuit falls at a rate that is lower than that of the output voltage in a state in which the DC/DC converter is suspended.
A shunt regulator employed in an insulated synchronous rectification DC/DC converter, wherein the DC/DC converter comprises:
- a transformer comprising a primary winding and a secondary winding;
- a switching transistor coupled to the primary winding of the transformer;
- a synchronous rectification transistor coupled to the secondary winding of the transformer;
- a photocoupler comprising a light-emitting element and a light-receiving element;
- a primary controller coupled to the light-receiving element of the photocoupler, and structured to perform switching of the switching transistor according to a feedback signal received from the light-receiving element;
- and
- a synchronous rectification controller structured to drive the synchronous rectification transistor,
- wherein the shunt regulator circuit comprises:
- a power supply pin structured to receive an auxiliary power supply voltage that falls at a slower rate than that of the output voltage in a state in which the DC/DC converter is suspended;
- a control input pin structured to receive the detection voltage;
- a control output pin coupled to the light-emitting element;
- an error amplifier structured to amplify a difference between the detection voltage and a reference voltage;
- a first transistor coupled to the control output pin, and structured to be driven according to an output signal of the error amplifier;
- and
- an overvoltage protection circuit structured such that, upon detecting an overvoltage state, a driving state of the light-emitting element is maintained,
- and wherein the auxiliary power supply voltage is supplied to at least a part of the overvoltage protection circuit.
Dependencies are inferred from the claim text.