The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 12, 2009
Filed:
Oct. 02, 2007
Douglas Paul Anderson, Nevada, IA (US);
Douglas Paul Anderson, Nevada, IA (US);
Micrel, Inc., San Jose, CA (US);
Abstract
An AC maintain power signature detection circuit in a power sourcing equipment (PSE) for a Power over Ethernet system injects an AC test signal onto a power port of the PSE. The AC test signal is driven onto a first power terminal of the power port through a sense resistor. The voltages across the sense resistor are measured and scaled by first and second resistor dividers having different resistor ratios. The voltage and the scaled voltage at the first power terminal side of the sense resistor have a peak voltage being proportional to the load impedance of the load coupled to the power port. The comparator compares the scaled voltages measured across the sense resistor and generates the output signal indicative of the load impedance at the power port.