FLY EZZY, Руководство по обслуживанию

Страница: 14 / 37

After the handset power off, the pin PWRKEY is pulled high. The pull-up resistance is inside the
chip .When the power key is pressed, the pin PWRKEY is pull low, then the MT6223A turn on all the Power supply
function and the baseband chip enter working status. So the pin BBWAKEUP is pulled
high. At that time, the power
key can be released; the CPU-baseband chip can control the MT6223A.
Charge Circuit
MT6223A charge management function:
1
、
Charger detection
2
、
Battery voltage measurement
3
、
Charging current measurement
4
、
Over voltage Protection
5
、
Charge mode selection
MT6223A is available to control the pulsed charging current. The pin CHRIN is to detect the
Charger. The pins ISENCE/BATSENES can calculate the battery voltage by detect the voltage of R400, and
calculate
the charge current by the voltage of the resistance R400. In different charge mode, Baseband
chip sent the
different PWM pulse signal to MT6223A, so the MT6233Acan control
the process of charge.
The charge process include three states: pre-charging mode, constant current mode and constant voltage
Mode. If the battery voltage is bellow 3.2V, the handset enter pre-charging mode; If the battery voltage
is over 3.2V, it enter the constant current mode; If the battery voltage is higher than 4.2V, it enter the
constant voltage mode