Alpha Omega Semiconductor Inc.

Kevin Ng

Allen Chang

Wai-Keung Peter Cheng

Zhinan Wei

A current limiting load switch for bridging supply Vss and load with a reference voltage VRdynamically generated by a VR-generator is proposed. It includes: A pair of power FET and sense FET interconnected in split-current configuration. The FET pair develops a load voltage while limiting load current Iload to a preset maximum Imax. The FET pair is sized to draw device currents Ipower and Is with RATIO=Is/Ipower&#x3c;&#x3c;1. The sense FET high-side terminal is coupled to Vss through a sense resistor Rsense developing a sense voltage Vs=Is&#xd7;Rsense. A current limiting amplifier with inputs connected to VRand Vs and output controlling FET pair closing a current limiting feedback loop. The VR-generator dynamically adjusts VRconcurrent and compensatory with an undesirable effect of changing RATIOcaused by the sense FET operational transition thus eliminating a transitional overshoot of Iload beyond Imax.

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Fremont, CA, United States of America

Kevin Ng