| 摘要 |
A current limit circuit regulates the current flow through a power switch 90 by measuring the current through the switch 90 and comparing it to a reference voltage V<SUB>REF </SUB>that represents the limit current. When the current through the power switch 90 is greater than the limit current, the current in the power switch 90 is pulled lower by a driver circuit 92 which controls the power switch 90 . By using a current limit reference voltage that has two levels, the power switch 90 has two current limit thresholds. Using a comparator 94 to compare the input voltage of the power switch 90 to the output voltage of the power switch 90 , an output signal is generated to control the current limit threshold. When the input voltage and output voltage has a large differential voltage, a lower current limit threshold voltage is selected. When the input voltage and output voltage has a small differential voltage, an upper limit threshold voltage is selected.
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