Specifications

26
Battery Charging and Supervision
Battery charging is managed by the DA9030 that supports constant current / constant
voltage charging, PWM and trickle charge modes, external DC detection, pre-charge, over
voltage and current lock out, battery removal and charge watchdog functions.
The charge DC signal is applied to the USB OTG connector. Thus, the battery may be
charged from a DC charger device with a mini USB connector or from a standard USB
host with a 5V power supply. External charger voltage must be between 4.5V and 5.5V.
The charging current is set in the power management software and may vary between
100mA and 1000mA.
During charging, battery temperature, voltage and charge current must be supervised, in
order to prevent battery over-heating or overcharge. These measurements are performed
with the DA9030 internal ADCs. Please see the “Battery charger control” section in the
DA9030 datasheet and the “Power Management” section in the O/S package
documentation for more details.
Power Modes
Active Mode
The active mode is entered after a successful start-up or pre-charge mode. During this
operating mode the PXA270 processor controls the system power management and is able
to respond to any faults that have been detected. Status information is passed to PXA270
via the I2C interface. The DA9030 can flag interrupt requests to the processor via a
dedicated interrupt pin.
Sleep Mode
The sleep mode may be entered from active mode only. The PXA270 processor is in deep
sleep mode and the DA9030 is in sleep mode. All power sources except for SDRAM deep
sleep self-refresh and RTC timekeeping power are shut down. The EM-X270 will wake-up
when one of the following events is detected: sleep/resume button (SW2) is pressed; an
external charger device is connected.
Pre-charge Mode
The pre-charge power mode is entered when the EM-X270 is powered up with a heavily
discharged battery (voltage below 3.45V) and an external DC charger is connected to the
device. The system will enable battery charging and wait until the battery voltage reaches
the 3.45V threshold. Only then, the EM-X270 will proceed with the standard boot
sequence. If the battery voltage is below 3.45V and there is no charger connected, the
system will go into shutdown.