Patent ID: 6424513
Filing Date: 2002-07-23
Classification: H02H

Abstract:
A short circuit protection device suitable for use with a power supply, said device comprising:a comparator having a non-inverting input port, an inverting input port, and an output port; a first voltage divider connected to the power plane of the power supply, said first voltage divider configured to provide a first reference signal to said non-inverting input port from said power plane voltage; a first time constant connected between said first voltage divider and said non-inverting input port, said first time constant for adding a first time delay to said first reference signal; a second voltage divider connected to the power supply output, said second voltage divider configured to provide a second reference signal to said inverting input port from said power supply output voltage, said second reference signal having a smaller voltage level than said first reference signal; and a second time constant connected between said second voltage divider and said inverting input port, said second time constant for adding a second time delay to said second reference signal, said second time delay being greater than said first time delay; such that i) a first logic state is present at said output port when said first reference signal voltage level remains greater than said second reference signal voltage level and ii) a second logic state, indicating the presence of a short circuit condition in the power supply, is produced at said output port when said first reference signal voltage level and said second reference signal voltage level are the same.