Contact corrosion mitigation
Methods, structures, and apparatus that limit the amount of dendritic growth and metal migration between contacts in order to prevent an erroneous detection of a connection and/or functional failure. One example may reduce dendritic growth and metal migration by limiting an amount of time that a connection detection voltage is applied to CC contacts of a USB Type-C connector when an electronic device is detecting a connection. This and other examples may further limit dendritic growth by not applying the connection detection voltage to the CC contacts for a first duration following a detection of a disconnection.
1. A method of operation of a dedicated downward-facing port for a USB Type-C™ interface, the method comprising:
applying a first voltage to a first end of a first resistor, where a second end of the first resistor is connected to a CC 1 contact of the dedicated downward-facing port and applying the first voltage to a first end of a second resistor, where a second end of the second resistor is connected to a CC 2 contact of the dedicated downward-facing port for a first duration; then
providing an open circuit at the CC 1 contact of the dedicated downward-facing port and an open circuit at the CC 2 contact of the dedicated downward-facing port for a second duration;
detecting a connection to the dedicated downward-facing port;
detecting a disconnection from the dedicated downward-facing port; then
waiting a third duration; then
applying the first voltage to the first end of the first resistor and applying the first voltage to the first end of the second resistor.
2. The method of claim 1 wherein the first duration plus the second duration are a total duration between 50 ms and 100 ms.
3. The method of claim 1 further comprising, while waiting a third duration:
providing the open circuit at the CC 1 contact and the open circuit at the CC 2 contact.
4. The method of claim 2 wherein the first duration is between 30 and 70 percent of the total duration.
5. The method of claim 3 wherein the third duration is between 0.5 and 2.0 seconds.
6. The method of claim 3 wherein the third duration is approximately 1.0 seconds.
7. A method of operation a dual-role port for a USB Type-C™ interface, the method comprising:
detecting a connection to the dual-role port;
detecting a disconnection from the dual-role port; then
waiting a first duration; then
applying a first voltage to a first end of a first resistor, where a second end of the first resistor is connected to a CC 1 contact of the dual-role port and applying the first voltage to a first end of a second resistor, where a second end of the second resistor is connected to a CC 2 contact of the dual-role port, further comprising, while waiting the first duration, providing an open circuit at the CC 1 contact and an open circuit at the CC 2 contact,
wherein the first duration is between 0.5 and 2.0 seconds.
8. The method of claim 7 wherein the first duration is approximately 1.0 seconds.
9. A dedicated downward-facing port for a USB Type-C™ interface comprising:
a first resistor having a first end to receive a voltage and a second end connected to a CC 1 contact of the dedicated downward-facing port;
a second resistor having a first end to receive the voltage and a second end connected to a CC 2 contact of the dedicated downward-facing port;
wherein the dedicated downward-facing port is configured to:
apply a first voltage to a first end of the first resistor and to the first end of the second resistor for a first duration; and
provide an open circuit at the CC 1 contact of the dedicated downward-facing port and an open circuit at the CC 2 contact of the dedicated downward-facing port for a second duration;
detect a connection to the dedicated downward-facing port;
detect a disconnection from the dedicated downward-facing port; then
wait a third duration; then
apply the first voltage to the first end of a first resistor and apply the first voltage to the first end of a second resistor.
10. The dedicated downward-facing port of claim 9 wherein the dedicated downward-facing port is further configured to, while waiting a third duration:
provide an open circuit at the CC 1 contact and an open circuit at the CC 2 contact.
11. The dedicated downward-facing port of claim 10 wherein the third duration is between 0.5 and 2.0 seconds.
12. The dedicated downward-facing port of claim 10 wherein the third duration is approximately 1.0 seconds.
13. A dedicated downward-facing port for a USB Type-C™ interface comprising:
a first resistor having a first end to receive a voltage and a second end connected to a CC 1 contact of the dedicated downward-facing port;
a second resistor having a first end to receive the voltage and a second end connected to a CC 2 contact of the dedicated downward-facing port;
wherein the dedicated downward-facing port is configured to:
apply a first voltage to a first end of the first resistor and to the first end of the second resistor for a first duration; and
provide an open circuit at the CC 1 contact of the dedicated downward-facing port and an open circuit at the CC 2 contact of the dedicated downward-facing port for a second duration, wherein the first duration plus the second duration are a total duration between 50 ms and 100 ms.
14. The dedicated downward-facing port of claim 13 wherein the first duration is between 30 and 70 percent of the total duration.
15. A dual-role port for a USB Type-C™ interface comprising:
a first resistor having a first end to receive a voltage and a second end connected to a CC 1 contact of the dual-role port;
a second resistor having a first end to receive the voltage and a second end connected to a CC 2 contact of the dual-role port;
wherein the dual-role port is configured to:
detect a connection to the dual-role port;
detect a disconnection from the dual-role port; then
wait a first duration; then
apply a first voltage to the first end of the first resistor and apply the first voltage to the first end of the second resistor for a first duration,
wherein the interface is further configured to, while waiting the first duration, provide an open circuit at the CC 1 contact and an open circuit at the CC 2 contact,
wherein the first duration is between 0.5 and 2.0 seconds.
16. The dual-role port of claim 15 wherein the first duration is approximately 1.0 seconds.