Dual mode over-current protection for switching mode power converter
AssigneeSemtech Corporation
InventorLei Hua
Life of this patent
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Abstract
A control circuit for a switched mode power converter is adapted to receive a current sense signal reflecting the output current of the power converter and a feedback signal reflecting the output voltage of the power converter. The control circuit includes a first over-current protection circuit adapted to shut off operation of the switched mode power converter if a sum of the current sense signal and the feedback signal exceed a first predetermined limit, and a second over-current protection circuit adapted to regulate operation of said primary side power switch responsive a comparison of the sum of the current sense signal and the feedback signal to a second predetermined limit. The second predetermined limit is less than the first predetermined limit.
Claims14
A switched mode power converter, comprising:
- a transformer having a primary winding and a secondary winding;
- a primary side power switch coupled to said primary winding and being adapted to periodically apply an input voltage to said primary winding;
- an output filter operatively coupled to said secondary winding to provide an output voltage and output current;
- a forward synchronous rectification device operatively coupled in series between said secondary winding and said output filter;
- a free-wheeling synchronous rectification device operatively coupled in shunt with said secondary winding and said output filter;
- and
- a control circuit adapted to receive a current sense signal reflecting the output current and a feedback signal reflecting the output voltage, the control circuit including a first over-current protection circuit adapted to shut off operation of the switched mode power converter if a sum of the current sense signal and the feedback signal exceed a first predetermined limit, and a second over-current protection circuit adapted to regulate operation of said primary side power switch responsive a comparison of the sum of the current sense signal and the feedback signal to a second predetermined limit, wherein said second predetermined limit is less than the first predetermined limit.
In a switched mode power converter comprising a transformer having a primary winding and a secondary winding, a primary side power switch coupled to said primary winding and being adapted to periodically apply an input voltage to said primary winding, an output filter operatively coupled to said secondary winding to provide an output voltage and output current, a forward synchronous rectification device operatively coupled in series between said secondary winding and said output filter, and a free-wheeling synchronous rectification device operatively coupled in shunt with said secondary winding and said output filter, a control circuit comprises:
- a first over-current protection circuit adapted to shut off operation of the switched mode power converter if a sum of a current sense signal reflecting the output current and a feedback signal reflecting the output voltage exceed a first predetermined limit;
- and
- a second over-current protection circuit adapted to regulate operation of said primary side power switch responsive a comparison of the sum of the current sense signal and the feedback signal to a second predetermined limit, wherein said second predetermined limit is less than the first predetermined limit.
Dependencies are inferred from the claim text.