Charge
The simple concept is to use an adapter and an external power supply to charge electronic products such as mobile phones. Charging refers to charging the battery.
This old fashioned adapter.
If there is no Meizu adapter;
Power Path Management Features
The chip's power path management is the ability to manage the flow of power.
For example:
if the mobile phone is roughly as shown above.
1. Plug in the charger to charge, the current mainly flows to the battery (path 2), but part of it is consumed by the system (path 1).
2. When you unplug the adapter, the power supply is provided by the battery, which is another path; (path 2 and path 1).
3. When the mobile phone is externally connected to a USB OTG device, this is another path 3;
otherwise, when wireless charging reversely charges other devices, this is another path.
Therefore, path management is to ensure that the system works correctly under various circumstances. This is the role of power path management.
Battery
The battery we are talking about is actually the battery cell plus the battery protection plate, which has protected the outer aluminum film and so on.
The battery protection board is briefly introduced as follows; the main purpose is to ensure that the battery can be charged normally within the specified range, and will not cause overheating, fire and other abnormalities due to charging.
The principle of the battery cell has been explained in many places, and you can understand it on Baidu. It is simply understood as the place where the charge is stored.
Charging IC
Charging path:
These are the main charging paths, and this is what we are most concerned about. The internal circuit is to ensure that the system will not cause safety problems due to various abnormalities during charging.
Such as:
safety
- thermal regulation and thermal shutdown: if the temperature is high, the output will be turned off or the chip will be turned off, and the charging will continue when the temperature drops.
– Input undervoltage lockout (UVLO) and overvoltage protection (OVP): When the input voltage is too high or too low, the system is not allowed to work to prevent damage to the chip or battery.
– Battery overcharge protection: It is to control the charging when it is fully charged. This is mainly to protect the battery.
– Pre-charge and fast-charge safety timer: This is to pre-charge with a small current when the battery is low.
– Charging is disabled if the current setting pin ICHG is open or short-circuited: this means that when our current setting pin is open, charging is not allowed, because it will cause uncontrollable charging when forced charging.
– Cold/hot battery temperature protection: Ensure that the battery is used within a reasonable range, because the temperature is too low to charge the battery, and the battery will be lost. .
– Fault report on STAT pin: Indicates the current state of charging, such as abnormality can be visually seen through the LED light.
battery charging current
Battery charging is divided into these four parts. When the battery is at low voltage, trickle charging starts, and then pre-charging, the current is greater than the first stage; when the battery voltage rises to a certain value, high-current charging starts; When the voltage is low, it starts to switch to low current charging.
The main reason is that lithium-ion batteries have a high energy ratio, so overcharging and over-discharging must be strictly prevented during battery use. Over-discharging will make it difficult to restore the active material. At this time, if you directly enter the fast charging mode (high current), it will damage the battery, affect the service life and may cause safety hazards. It is necessary to charge to 2.5V to 3.0V with a small current (C/10) before converting to fast charging.