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CHAPTER 15 PMU (POWER MANAGEMENT UNIT)
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15.1.3 Power-on Control
The factors to start the CPU (to set the state where the shutdown state or Hibernate mode state have
shifted to the Fullspeed mode) are called starting factors and there are three types of starting factors:
power-switch interrupt, DCD interrupt, and alarm interrupt.
On the other hand, there are two types of factors to hinder the starting of the CPU: detection of battery
runout and detection of battery lock interrupt. However, when the starting of the CPU is hindered by the
detection of battery lock interrupt, the operation of the CPU becomes unstable, so be sure to set the
GPIO[9] (BATTLOCK) terminal to the High state (Lock state) when the CPU is in the Hibernate state or
shutdown state (MPOWER=0).
(1) Starting by a Power-Switch Interrupt
When the POWER signal is asserted, the PMU notices other units that it is going to start the CPU by
asserting the POWERON signal. After asserting the POWERON signal and checking the BATTINH
signal, the PMU deasserts the POWERON signal.
If the BATTINH signal is High ("1"), the PMU releases the reset of peripheral units by deasserting the
rst_gab signal (internal) and starts the CPU core by staring the cold reset sequence.
If the BATTINH signal is Low ("0"), the PMU shuts down again by setting the BATTINH bit of
PMUINTREG to 1. After the CPU has been restarted, the BATTINH bit must be checked and cleared
by software.
Figure 15-1. Starting by a Power-Switch Interrupt (BATTINH=1)
BATTINH
MPOWER
RTC
POWER
POWERON
H
Figure 15-2. Starting by a Power-Switch Interrupt (BATTINH=0)
BATTINH
MPOWER
RTC
POWER
POWERON
L
L