Accessory device for managing multiple power sources
Aspects of the present disclosure provide techniques, including devices and systems implementing the techniques, for managing multiple power sources using an accessory device. One example accessory device includes a first power supply node configured to receive power from an alternative power source, a second power supply node configured to be coupled to a universal serial bus (USB)-C plug of a primary power source, an output power supply node configured to be coupled to a USB-C receptacle, and a management circuit. The management circuit includes an input node coupled to a first control configuration (CC) input line and a second CC input line; a first output node coupled to a first CC output line; and a second output node coupled to a second CC output line. The management circuit is configured to maintain an impedance of the CC input lines and CC output lines within a range.
1. A device, comprising:
a first power supply node configured to receive power from an alternative power source;
a second power supply node configured to be coupled to a universal serial bus (USB)-C plug of a primary power source;
an output power supply node configured to be coupled to a USB-C receptacle, wherein the output power supply node is configured to be coupled to the first power supply node and the second power supply node; and
a management circuit, comprising:
an input node coupled to a first control configuration (CC) input line and a second CC input line, wherein the first CC input line and the second CC input line are coupled between the second power supply node and the management circuit;
a first output node coupled to a first CC output line; and
a second output node coupled to a second CC output line, wherein the first CC output line and the second CC output line are both coupled between the management circuit and the output power supply node, wherein the first CC input line and the second CC input line are coupled to the second CC output line, and wherein the management circuit is configured to maintain an impedance of the first CC input line, the second CC input line, the first CC output line, and the second CC output line within a range.
2. The device of claim 1 , wherein the management circuit further comprises:
a first resistor coupled to the first CC output line; and
a switch coupled between the first power supply node, the second power supply node, and the first resistor, wherein the range is based, at least in part, on at least one USB-C standard associated with the first CC input line and the second CC input line, and wherein the management circuit is further configured to pull up a voltage at the first CC output line or a voltage at the second CC output line.
3. The device of claim 2 , wherein when the first power supply node is receiving power from the alternative power source and the second power supply node is not coupled to the USB-C plug, the management circuit is configured to close the switch, and pull up the voltage at the first CC output line to a voltage at the first power supply node using the first resistor.
4. The device of claim 2 , wherein when the first power supply node is not receiving power from the alternative power source and the second power supply node is not coupled to the USB-C plug, the management circuit is configured to open the switch such that the first CC output line is floating.
5. The device of claim 2 , wherein when the first power supply node is not receiving power from the alternative power source and the second power supply node is coupled to the USB-C plug:
the management circuit is configured to open the switch such that the first CC output line is floating;
the second CC output line is shorted to the first CC input line and the second CC input line;
the output power supply node is coupled to the USB-C receptacle;
the USB-C receptacle is coupled to another device; and
the other device pulls up the first CC input line and the second CC input line.
6. The device of claim 2 , wherein when the first power supply node is receiving power from the alternative power source and the second power supply node is coupled to the USB-C plug:
the management circuit is configured to open the switch such that the first CC output line is floating;
the second CC output line is shorted to the first CC input line and the second CC input line;
the output power supply node is coupled to the USB-C receptacle;
the USB-C receptacle is coupled to another device; and
the other device pulls up the first CC input line and the second CC input line.
7. The device of claim 2 , wherein a value of the first resistor is based on at least one of a USB-C standard or an output current rating of the alternative power source.
8. The device of claim 2 , wherein the switch comprises a transistor, and wherein a gate of the transistor is coupled to the second power supply node.
9. The device of claim 8 , wherein:
the management circuit further comprises a second resistor and a third resistor both coupled between the gate of the transistor and the second power supply node;
the second resistor is configured to be a pull up resistor for the gate of the transistor; and
the third resistor is configured to be a pull down resistor for the gate of the transistor.
10. The device of claim 1 , wherein the alternative power source comprises a wireless charger.
11. The device of claim 1 , further comprising a data line pass through configured to be coupled between at least one data line of the USB-C plug and at least one data line of the USB-C receptacle.
12. The device of claim 1 , further comprising a power multiplexer (MUX), comprising:
a first input coupled to the first power supply node;
a second input coupled to the second power supply node; and
an output coupled to the output power supply node.
13. The device of claim 12 , wherein when a voltage at the first power supply node and a voltage at the second power supply node are each valid, the power MUX is configured to select the second power supply node.
14. A device, comprising:
a first power supply node configured to receive power from an alternative power source;
a second power supply node configured to be coupled to a universal serial bus (USB)-C plug of a primary power source;
an output power supply node configured to be coupled to a USB-C receptacle, wherein the output power supply node is configured to be coupled to the first power supply node and the second power supply node; and
a management circuit, comprising:
an input node coupled to a first control configuration (CC) input line and a second CC input line, wherein the first CC input line and the second CC input line are coupled between the second power supply node and the management circuit;
a first output node coupled to a first CC output line; and
a second output node coupled to a second CC output line, wherein the first CC output line and the second CC output line are both coupled between the management circuit and the output power supply node, wherein the first CC input line and the second CC input line are coupled to the second CC output line, and wherein the management circuit is configured to pull up a voltage at the first CC output line or the second CC output line.
15. A method for routing power to a first device, the method comprising:
routing power from a first power supply node of a second device or a second power supply node of the second device to an output power supply node of the second device, wherein the first power supply node is configured to receive power from an alternative power source, wherein the second power supply node is configured to be coupled to a universal serial bus (USB)-C plug of a primary power source, and wherein the output power supply node is configured to be coupled to the first device via a USB-C receptacle;
maintaining, using a management circuit, an impedance of a first control configuration (CC) input line, a second CC input line, a first CC output line, and a second CC output line within a range, wherein the first CC input line and the second CC input line are coupled to the second CC output line.
16. The method of claim 15 , wherein the management circuit comprises:
a first resistor coupled to the first CC output line; and
a switch coupled between the first power supply node, the second power supply node, and the first resistor, wherein the range is based, at least in part, on at least one USB-C standard associated with the first CC input line and the second CC input line, and wherein the management circuit is further configured to pull up a voltage at the first CC output line or a voltage at the second CC output line.
17. The method of claim 16 , wherein when the first power supply node is receiving power from the alternative power source and the second power supply node is not coupled to the USB-C plug, the management circuit is configured to close the switch, and pull up the voltage at the first CC output line to a voltage at the first power supply node using the first resistor.
18. The method of claim 16 , wherein when the first power supply node is not receiving power from the alternative power source and the second power supply node is not coupled to the USB-C plug, the management circuit is configured to open the switch such that the first CC output line is floating.
19. The method of claim 16 , wherein when the first power supply node is not receiving power from the alternative power source and the second power supply node is coupled to the USB-C plug:
the management circuit is configured to open the switch such that the first CC output line is floating;
the second CC output line is shorted to the first CC input line and the second CC input line;
the output power supply node is coupled to the USB-C receptacle;
the USB-C receptacle is coupled to another device; and
the other device pulls up the first CC input line and the second CC input line.
20. The method of claim 16 , wherein when the first power supply node is receiving power from the alternative power source and the second power supply node is coupled to the USB-C plug:
the management circuit is configured to open the switch such that the first CC output line is floating;
the second CC output line is shorted to the first CC input line and the second CC input line;
the output power supply node is coupled to the USB-C receptacle;
the USB-C receptacle is coupled to another device; and
the other device pulls up the first CC input line and the second CC input line.