Fairchild Semiconductor Corporation

Kenneth O'Brien

Kenneth Patrick Snowdon

Gregory A Maher

Yongliang Li

Peng Zhu

Jianing Zhou

Randall Wetzel

This document discusses, among other things, an impedance detection circuit, method, and integrated circuit, comprising a ramp-up current generation circuit and an impedance determining circuit, wherein the ramp-up current generation circuit is configured to input a ramp-up current including n breaks to a port of a device where the ramp-up current generation circuit is disposed, to which port an external device is connected, and wherein the impedance determining circuit is configured to detect an impedance of the external device in each break time period of the ramp-up current input by the ramp-up current generation circuit until the impedance of the external device is acquired by detection in the last break time period of the n breaks.

Impedance detection circuit, method, and integrated circuit

This document discusses, among other things, a detection circuit configured to receive an output of a window comparator over a range of input values and to measure a difference between first and second thresholds of the window comparator, and a trim circuit configured to adjust at least one of the first or second thresholds using the measured difference between the first and second thresholds.

Window reference trimming for accessory detection

An apparatus comprises a connector configured to receive an electrical contact of an accessory device that is electrically coupled to a resistor of the accessory device, a current source configured to apply a specified current to the resistor to generate a resulting voltage, a comparator configured to receive and compare the resulting voltage to a reference voltage, and a controller configured to store an outcome of the comparison as a bit in a register, to adjust the applied current using the outcome of the comparison, and to determine a resistance value for the resistor using the bit stored in the register.

Growing community of inventors

Gorham, ME, United States of America

Kenneth O'Brien