USB Power Delivery Source Device Sleep Mode
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Solution Overview
Problem
USB power-delivery source devices consume significant power when providing power to other devices, especially when no connected device is present at the far end of the cable, as they maintain DC voltage and continuously monitor for responses, leading to inefficiencies.
Innovation Solution
Implementing a device sleep mode and abbreviated source capabilities messages to reduce power consumption by disabling the FSK receiver and other components when no response is received, and using a longer extended time period for sending source capabilities messages, along with sending abbreviated messages until a valid response is received.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the USB power-delivery source device maintains DC voltage and continuously monitors for responses, then it ensures compliance with USB Power Delivery Specification and interoperability, but it consumes significant power especially when no connected device is present
Solution Approach 1:
The source device transitions from continuous monitoring to periodic monitoring by implementing an extended time period during which it does not send source capabilities messages. After this extended period passes without receiving a response, the device sends an abbreviated source capabilities message and enters a sleep mode, waking only to monitor for specific response signals. This periodic action significantly reduces power consumption while maintaining compliance.
Solution Approach 2:
The source device dynamically adjusts its operational state based on whether a response is received. It can transition between active monitoring state and sleep mode, and between sending full source capabilities messages and sending abbreviated messages. This dynamic adaptation allows the device to maintain reliability when needed while minimizing power consumption during idle periods.
2Reliability
If the source device sends full source capabilities messages continuously, then it ensures proper device negotiation and power delivery setup, but it increases communication overhead and power consumption
Solution Approach 1:
The source device sends only an abbreviated source capabilities message after the extended time period instead of the full message used during initial connection. This partial action is sufficient for maintaining the power delivery relationship when no device disconnection has occurred, reducing communication overhead and energy loss while still ensuring proper negotiation when needed.
Data Source
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AI summary
In described examples of methods of reducing power consumption in a USB power-delivery source device (100), one or more source capabilities messages are sent by the USB power-delivery source device (100). If, after sending a source capabilities message, a response to the source capabilities message is not received within a predetermined time period, the device sends another source capabilities message. If, after sending a predetermined number of source capabilities messages, no response is received, the device waits an extended period of time before sending another source capabilities message. Receiving functionality, e.g., receiver (122), of the USB power-delivery source device (100) is turned off during some or all of the extended period of time.