Quick Charge, explained.

How QC negotiates — and why that put it on USB-A

USB-C PD talks over the CC (Configuration Channel) pin, a dedicated wire that only exists on a USB-C connector. Quick Charge 2.0 and 3.0 predate that: they signal by placing specific DC voltages on the D+ and D− data lines, the same pins USB 2.0 uses for data. That trick works on a plain USB-A port, which is exactly why QC became the standard for USB-A fast charging and why almost every "18W USB-A" port on a multi-port brick is a QC port.

It is also why QC on a USB-C port is a problem. The USB-C specification forbids raising VBUS above 5V without a proper PD contract, because a legacy device plugged into a C-to-A adapter could receive 9V or 12V it never asked for. Compliant chargers therefore keep QC on their A ports and PD on their C ports.

The ladder, version by version

QC 3.0's "INOV" step-tuning was the ancestor of the idea that later became PPS in the USB standard. The convergence is the important part: Qualcomm made QC 4 a strict superset of USB-C PD, so a QC 4+ phone is a PD phone, and any competent USB-C PD adapter charges it at full speed with no Qualcomm silicon involved.

What this means when you are shopping

Treat "QC 3.0" on a listing as a description of the USB-A port, not a feature of the charger. It is genuinely useful for older hardware — a 2017 Android phone, a Bluetooth speaker, a dashcam, a power bank with a Micro-B input — and worth nothing to anything made in the last five years. The failure mode people hit is the reverse of what they expect: buying a QC-only USB-A brick for a modern USB-C phone, then wondering why it is stuck at 10W over a C-to-A cable, because a USB-A source cannot supply a PD contract at all.

Head-to-head detail lives on PD vs Quick Charge, and the connector-level argument on USB-A vs USB-C. If you are replacing an old QC brick outright, the 30W and 65W pages cover the modern equivalents.

Devices that still care

Quick Charge is a Snapdragon feature, so it appears on Qualcomm-powered phones and tablets: older Galaxy models, LG, Motorola, Sony, HTC, plus a long tail of Android tablets and accessories. Samsung's own "Adaptive Fast Charging" is QC 2.0 relabelled. Devices that never supported it: every iPhone and iPad, MediaTek and Exynos handsets that use their own schemes, the Nintendo Switch, and every USB-C laptop — those all speak standard USB PD instead.

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