| 摘要 |
A embedded overcurrent protection circuit within the PWM feedback controller ( 30 ) of a power converter ( 100 ) having an novel current limit detection function that minimizes the effects of the turn-on period of the power device ( 14 ) is disclosed herein. This power converter includes a current limit detection circuit ( 10 - 20 ) that is reset on the rising edge of the system clock in a first step. In a second step, the power device ( 14 ) that is turned on. In another step, a current detecting circuit ( 10 - 20 ) detects the drain-to-source voltage across the power device ( 14 ) and the output current generated thereby. A sense circuit ( 18 ) compares the output current detected with a first predetermined limit value in another step. When the output current is less than the first predetermined limit value, a step is conducted where the output current is regulated by modulating the pulse width of the signal sent by a driver ( 12 ) to the control node of the power device ( 14 ). In the alternative, when the output current exceeds the first predetermined limit value, the power device ( 14 ) is turned off and the synchronous rectifier ( 16 ) is turned on while its current is monitored at a second predetermined limit value in another step. This synchronous rectifier ( 16 ) monitoring step enables the current limit detection circuit ( 10 - 20 )to minimize the effects of the turn-on period of the power device ( 14 ). Finally, the current limit detection circuit ( 10 - 20 ) is reset on the rising edge of the system clock and wherein this entire procedure is continuous.
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