When the mobile phone fast charging source adapter is connected to the SL04 box and used offline, you need to pay attention to the following matters:
1: SL04 box with internal isolation, in order to isolate the output, there is a 5V to 5V power isolation chip, the normal voltage input range fluctuates to +-10%, so when the box is connected to the USB power supply, the USB power supply can not exceed the range of 4.5V-5.5V, the chip can withstand the voltage of 6V in the short term, and more than 6.5V will burn the isolated power chip, which will cause all the output of the SL04 box to have no power supply, so the 4 ports of SL04 will have no output.
The main chip has an LDO, and the input can withstand a voltage of 15V without burning the chip, so the box can continue to work, but there is no output.
2: The fast charging source adapter will output 5V, 9V, 12V, and 20V voltages through the protocol, so when connecting the SL04 box, you need to pay attention to the following matters.
A: For example, if QC2.0 fast charging needs to output 9V, the D+ D- voltage is 3.3V/0.5V, and if it needs to output 12V, the D+ D- voltage will be adjusted to 0.5V/0.5V, and the voltage will not be boosted without feedback, and the 5V output will be maintained. (This adapter is not safe, because the D+ D- voltage will be uncertain at the moment of USB insertion, and the voltage will be output greater than 5V in case of false detection)
B: After the PD3.0 PPS is plugged into the cable, the charger will send a data packet (PDO broadcast) to the device, telling the device that I am a charger with 5V3A / 9V3A / 12V3A / 15V3A / 20V2.25A, and only switch the voltage after communicating through the protocol. (This kind of protocol is safe, and the voltage needs to be switched through the protocol)
C: It is not safe to check the power adapter of CC1 and CC2 only.
D: Normal USB power adapter is safe and will only output 5V.