User Manual

element14 is a trademark of Premier Farnell plc 43

6.1.8.3 LDO_GOOD

This signal connects to the

RTC_PORZn

signal, RTC power on reset. The small

indicates that the signal is an active low signal. Word processors seem to be unable to put

a bar over a word so the

is commonly used in electronics. As the RTC circuitry comes

up first, this signal indicates that the LDOs, the 1.8V VRTC rail, is up and stable. This

starts the power up process.

6.1.8.4 PMIC_PGOOD

Once all the rails are up, the

PMIC_PGOOD

signal goes high. This releases the

PORZn

signal on the processor which was holding the processor reset.

6.1.8.5 WAKEUP

The WAKEUP signal from the

TPS65217C

is connected to the

EXT_WAKEUP

signal on

the processor. This is used to wake up the processor when it is in a sleep mode. When an

event is detected by the

TPS65217C,

such as the power button being pressed

generates this signal.

6.1.8.6 PMIC_INT

The

PMIC_INT

signal is an interrupt signal to the processor. Pressing the power button

will send an interrupt to the processor allowing it to implement a power down mode in an

orderly fashion, go into sleep mode, or cause it to wake up from a sleep mode. All of

these require SW support.

6.1.9 Power Rails

Figure 25

shows the connections of each of the rails from the

TPS65217C