PCF5083 datasheet(18/136 Pages) PHILIPS

18 / 136 page

1996 Oct 29

Philips Semiconductors

Objective speciﬁcation

GSM signal processing IC

PCF5083

8.2.2

MOBILE SWITCH-OFF PROCEDURE

The switch-off request to the System Controller is initiated

via a LOW-to-HIGH transition and hold of pin ONKEY for

longer than 1 second or a LOW level on pin LOWVOLT.

The HWCTRL_INT interrupt is activated if one of these

conditions has set it’s corresponding flag in register

HWCTRL_REG.

The next step is to deactivate the POWON signal.

Therefore the flag HWCTRL_REG[SWOFF] has to be set.

If the SWOFF flag is not set within 8 seconds (see

Section 8.2.3) and the Watchdog Timer expires, POWON

is deactivated without any further interaction. The SWOFF

flag is automatically cleared when the mobile is switched

on again.

The PCF5083 is immediately and under all conditions

forced into the off state with RSTO asserted LOW.

Table 6

Mobile switch-off request conditions

ONKEY

LOWVOLT

COMB_INT

L ¡ HX

H ¡ L

XH ¡ LH ¡ L

It should be noted that:

• If POWON is LOW (switch-off state), all outputs of the

PCF5083 except POWON and NPOWON are in their

high-impedance state.

• The hardware control interrupt (HWCTRL_INT) is not

asserted externally but stays internally pending during

Sleep mode. The timing generator unit is forced into

wake-up state if the hardware control interrupt is

asserted internally.

• Other interrupt conditions, caused by the MMI

power-down unit and the real time clock unit, are also

indicated with the hardware control interrupt. These

conditions are mentioned in the appropriate sections.

• The interrupt flags in register HWCTRL_REG have to be

cleared by the System Controller to deactivate the

interrupt condition. A flag is cleared by writing a logic 1

to its bit location.

Table 7

Mobile switch-off conditions

HWCTRL_REG[SWOFF]

OFF/WATCHDOG TIMER EXPIRES

RSTO

POWON

Lno

L ¡ Hno

H ¡ L

yes

H ¡ L

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