LG -T370 Service Manual page 26

3. TECHNICAL BRIEF
3. TECHNICAL BRIEF
For details on pre-charging see the charger chapter. The charger is controlled by an independent state
machine. The pre-charge signal is used to trigger the pre-charge signal is used to trigger the pre-charge
functionality. The charger state machine fully control the pre-charge, the PMU-state machine now changes to
state HPBG on state and the system starts. This state change is indicated to the charger state-machine to
enable the charger watchdog for safety
3.2.6 Power Supply Start-up sequence
In order to avoid an excessive drop on the battery voltage caused by in-rush current during system power-on,
possibly leading to system instability and "hick-ups" a staggered turn-on approach for the regulators is
implemented. The regulators are turned on in a well defined sequence, thus spreading the in-rush current
transients over time.
The IO's of X-GOLD TM 215 are isolated in OFF mode (core supply is off). The isolation signal is controlled by
the PMU state machine. This ensures that the PADs are in a well defined state during core supply settling. This
allows to power up the LCORE core regulator and wait for the core to reach reset state before powering up the
I/O supply regulators.
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