Qualcomm QC2.0 era

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Qualcomm QC2.0 era

The charger first steps down the family's standard voltage of 220V to 5V output to the microUSB interface of the mobile phone a few years ago (the so-called Android flat head), and then the internal circuit of the mobile phone is stepped down to about 4.3V to charge the battery. There are two steps in the buck.

Before QC1.0, everyone thought about how to increase the current. In the era of QC1.0, that is, in the era of 5V2A, the original data line has been affected by the bottleneck. If the current continues to increase, it will inevitably cause damage to the charging line. The ordinary charging line can only pass 2A, and the better charging line can reach 3A. The wonderful vooc charging line like oppo can reach 4A (this later).

Therefore, Qualcomm thought of increasing the charging power by increasing the charging voltage, so QC2.0 was born. Qualcomm divides QC2.0 into two categories: Class A and Class B. Class A provides 5V, 9V, and 12V voltages. Class B provides 5V, 9V, 12V, and 20V voltages, of which 20V is for notebooks. (Here is a whisper, the chargeturbo fast charging of Xiaomi 9 is actually QC3.0ClassB standard, using the 20V1.35A gear to achieve 27V fast charge.), here again, Samsung insisted on 5 years of AFC charging It is the vest of QC2.0.

However, QC2.0 has a shortcoming, that is, the charging rate is equivalent to today's charging is still a bit slow, and the mobile phone generates a lot of heat (think QC2.0 + Snapdragon 810 processor), because the lithium battery is actually acceptable for charging. The voltage is 4.35V (the lithium-ion battery charging voltage of some mobile phones is 4.2V and 4.4V), so in fact, whether the input voltage of the USB interface of the mobile phone is 5V or 20V, the internal voltage of the mobile phone must be equipped with a step-down circuit to reduce the input voltage. 4.35V. However, the 20V voltage in the mobile phone to complete the 4.35V step-down conversion will generate a lot of heat, resulting in the phone charging temperature is too high, it is prone to explosion risk.

And QC2.0 must use a dedicated charging head, but in order to ensure that the adapter supports 5V devices down, Qualcomm introduced a handshake protocol in the QC 2.0 protocol. The handshake protocol of QC2.0 communicates with DP (D+, DigitalPositive) and DM (D-, DigitalMinus) two-pin data terminals of Micro-USB / USB-A / USB-C interface, and the smart phone actively applies to QC2.0 charger. The high voltage input can increase the maximum charging voltage to 20V after confirmation. The QC2.0, which must use a dedicated charger, has become a lifeline for the upstream and foundry industries. Since then, the fast charge industry has experienced explosive growth.