MOISTURE DETECTION CIRCUITS AND METHODS FOR SERIAL BUS CONNECTORS

1 . A moisture detection circuit for serial bus connectors, comprising:

a current digital-to-analog converter that receives a first digital signal indicating a current reference value and outputs an analog current with a magnitude that corresponds to that of the first digital signal to a terminal of the serial bus connectors;

a voltage digital-to-analog converter that receives a second digital signal indicating a voltage reference value and outputs an analog voltage with a magnitude that corresponds to that of the second digital signal;

a comparator that compares a voltage of the terminal of the serial bus connectors with a voltage output by the voltage digital-to-analog converter; and

a controller that provides a first digital signal indicating the current reference value to the current digital-to-analog converter and provides a second digital signal indicating the voltage reference value to the voltage digital-to-analog converter to determine presence or absence of moisture adhering to the terminal based on comparison results of the comparator.

2 . The moisture detection circuit for serial bus connectors according to claim 1 ,

wherein the current digital-to-analog converter outputs a current of a first current reference value in a first period of time P 1 and a second period of time P 2 , and outputs a current of a second current reference value in a third period of time P 3 and a fourth period of time P 4 ;

the voltage digital-to-analog converter outputs a voltage of a first voltage reference value in the first period P 1 and the third period P 3 , and a voltage of a second voltage reference value in the second period P 2 and fourth period P 4 ;

the comparator compares the terminal voltage with the voltage output by the voltage digital-to-analog converter in each of the first period P 1 to fourth period P 4 ; and

the controller determines whether there is moisture adhered to the terminal of the serial bus connectors based on the comparison result of the comparator in the first period P 1 to fourth period P 4 ;

wherein a time order of the first period P 1 to the fourth period P 4 is arbitrary.

3 . The moisture detection circuit for serial bus connectors according to claim 2 ,

wherein the controller determines that the terminal is adhered by moisture when following conditions are met:

the first current reference value is less than the second current reference value;

the first voltage reference value is greater than the second voltage reference value;

the terminal voltage is less than the first voltage reference value in the first period P 1 ;

the terminal voltage is greater than the second voltage reference value in the second period P 2 ;

the terminal voltage is greater than the first voltage reference value in the third period P 3 ; and

the terminal voltage is greater than the second voltage reference value in the fourth period P 4 .

4 . The moisture detection circuit for serial bus connectors according to claim 2 ,

wherein the controller determines that a normal accessory is mounted on the terminal when following conditions are met:

the first current reference value is less than the second current reference value;

the first voltage reference value is greater than the second voltage reference value;

the terminal voltage is less than the first voltage reference value in the first period P 1 ;

the terminal voltage is less than the second voltage reference value in the second period P 2 ;

the terminal voltage is less than the first voltage reference value in the third period P 3 ; and

the terminal voltage is greater than the second voltage reference value in the fourth period P 4 .

5 . The moisture detection circuit for serial bus connectors according to claim 1 , wherein

the current digital-to-analog converter is a 1-bit digital-to-analog converter capable of selectively outputting a current of a first current reference value and a current of a second current reference value; and

the voltage digital-to-analog converter is a 1-bit digital-to-analog converter capable of selectively outputting a voltage of a first voltage reference value and a voltage of a second voltage reference value.

6 . The moisture detection circuit for serial bus connectors according to claim 1 ,

wherein the moisture detection circuit further includes an edge detector that detects a rising or falling edge of a signal provided to the terminal by a host controller to create an enable signal, and provides the enable signal to the controller.

7 . The moisture detection circuit for serial bus connectors according to claim 6 ,

wherein the controller starts moisture detection operation based on the enable signal output by the edge detector.

8 . The moisture detection circuit for serial bus connectors according to claim 1 ,

wherein the controller opens a switch that connects the terminal with a host controller when it is determined that the terminal is adhered by moisture.

9 . A moisture detection method by a moisture detection circuit for serial bus connectors, comprising:

a first period comparison step of comparing a terminal voltage and a first voltage reference value while applying a current of a first current reference value to a terminal of the serial bus connectors;

a second period comparison step of comparing the terminal voltage and a second voltage reference value while applying a current of the first current reference value to the terminal of the serial bus connectors;

a third period comparison step of comparing the terminal voltage and the first voltage reference value while applying a current of a second current reference value to the terminal of the serial bus connectors;

a fourth period comparison step of comparing the terminal voltage and the second voltage reference value while applying a current of the second current reference value to the terminal of the serial bus connectors; and

determining whether the terminal is adhered by moisture based on comparison results from the first period comparison step to fourth period comparison step.

10 . The moisture detection method by a moisture detection circuit for serial bus connectors according to claim 9 , further comprises:

determining that the terminal of the serial bus connectors is adhered by moisture when following conditions are met:

the first current reference value is less than the second current reference value;

the first voltage reference value is greater than the second voltage reference value;

the terminal voltage is less than the first voltage reference value in the first period comparison step;

the terminal voltage is greater than the second voltage reference value in the second period comparison step;

the terminal voltage is greater than the first voltage reference value in the third period comparison step; and

the terminal voltage is greater than the second voltage reference value in the fourth period comparison step.

11 . The moisture detection method by a moisture detection circuit for serial bus connectors according to claim 9 , further comprises:

determining that a normal accessory is mounted on the terminal of the serial bus connectors when following conditions are met:

the first current reference value is less than the second current reference value;

the first voltage reference value is greater than the second voltage reference value;

the terminal voltage is less than the first voltage reference value in the first period comparison step;

the terminal voltage is less than the second voltage reference value in the second period comparison step;

the terminal voltage is less than the first voltage reference value in the third period comparison step; and

the terminal voltage is greater than the second voltage reference value is greater than the fourth period comparison step.

12 . The moisture detection method by a moisture detection circuit for serial bus connectors according to claim 9 ,

wherein the moisture detection method is initiated based on a rising edge or falling edge of a signal provided by a host controller to the terminal of the serial bus connectors.