Yes, when choosing a charger, pay attention to the following points, so that a small current can charge a large current:
1. Is the output voltage the same as original?
2. Is the output current the same as the original?
3. Is the power output the same as original?
4. Whether the charging interface of the power supply matches the electrical appliance.
Note: A low current charger can charge a high current battery, but there is a prerequisite, that is, the output voltage of the charger is the same. In addition, the charging time will be longer and the battery may even be dissatisfied with the charge.
Four common interfaces: Mini USB interface is the oldest, and some MP3 players and others still maintain this interface. Micro USB interface is the most common, most Android phones have this interface, Type-C interfacecan. be plugged in from both sides, so you don't have to worry about damaging the plug when inserted upside down. Some high-end Android phones have this type of interface, and the Lightning interface is a dedicated interface for Apple.
The data cable interface should be the primary consideration and charger settings cannot be ignored. If we use 5V/1A charger to charge the cell phone, the charger will always be overcharged and the charger will heat up. Long-term use will shorten the life of the charger. The most important thing is the charging speed. also very slow.
First, you need to know the designer’s goal. The front stage of this circuit is a lithium battery charge management circuit, and the rear stage is a 5V to 3.3V circuit. These two parts are relatively simple. We mainly analyze this part of the circuit composed of SD1, SD2, Q1 and. R10. The purpose of adding this part of the circuit is that when the lithium battery is charging, the 3.3V voltage stabilization circuit is powered by VUSB, and after the VUSB is removed, 3.3V is powered by the battery. Originally only the SD1 was needed to achieve this, but the designer considered that the SS14 Schottky diode would also have a voltage drop of around 0.2 V. When the battery voltage is sent to the circuit voltage stabilization of 3.3 V, 0.2 V will be subtracted. In order to reduce the voltage drop, Q1 is used here to achieve this. When VUSB is connected externally, the gate potential of Q1 is higher than that of the source and Q1 is turned off. Once VUSB is removed, the gate of Q1 is grounded, the potential is lower than that of the source and Q1 is activated. The on-resistance of the MOS tube is very small, and the voltage drop can be ignored when the current is not large. GrThrough analysis, we can know that the circuit can still work normally without Q1, but the lithium battery is less than 3.5V (assuming that the 3.3V voltage stabilization IC has a low voltage drop) and the 3.3V voltage stabilization circuit cannot produce a signal. stable 3.3V. After adding Q1, once the lithium battery is lower than 3.3V (assuming that the 3.3V voltage stabilization IC has a small voltage drop), the 3.3V voltage stabilization circuit output is lower than 3.3V. If the lithium battery will not be used below 3.6V and the 3.3V voltage stabilization IC has a low voltage drop, Q1 can be removed. Another point to add: this circuit has a very big flaw. When charging the lithium battery, VUSB can charge the battery via the protect diodeinternal inverse ion of Q1. The constant current charging process of the lithium battery management circuit is destroyed and the lithium is destroyed. the battery is equal to a constant voltage., which means that removing the lithium battery charging circuit from this circuit will not have much impact.