FLY E185
Service Manual
CKT Confidential
Page 17 of 47
sequence. In addition, when the battery voltage is getting lower and lower, it will enter UVLO
state and the PMU will be turned-off by itself, except for V
rtc
LDO, to prevent further discharging.
Once the PMU enters UVLO state, it draws low quiescent current. The RTC LDO is still working
until the DDLO disables it.
Deep Discharge Lockout (DDLO)
PMU will enter to the deep discharge lockout (DDLO) state when the battery voltage drops below
2.5V. In this state, the V
rtc
LDO will be shutdown. Otherwise, it draws very low quiescent current
to prevent further discharging or even damage to the cells.
Reset
The PMU contains a reset control circuit which takes effect at both power-up and power-down.
The RESETB pin is held at low in the beginning of power-up and returns to high after the
pre-determined delay time. The delay time is controlled by a large counter, which use clock from
internal ring-oscillator. At power-off, RESETB pin will return to low immediately without any
delay.
3.3.3 Battery Charging Circuit
Battery Charger Flow Chart:
