USB-C Power Delivery: A Negotiation of Power Modes
2025-09-01
USB-C power delivery isn't a simple pass-through; it's a sophisticated negotiation. The source first broadcasts its supported voltages, current limits, and features (including optional PPS mode, allowing the sink to fine-tune voltage and current). The sink selects a mode and sends a request. The source assesses and decides to accept or reject. Upon acceptance, the source prepares the power and sends a ready signal. The sink also sends acknowledgements. Furthermore, Vendor Defined Messages (VDMs) negotiate data direction and other information; their openness determines whether they're good or bad.
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Hardware
Power Delivery