Philips P89LPC906 Computer Monitor User Manual


 
Philips Semiconductors
User’s Manual - Preliminary -
P89LPC906/907/908
POWER MONITORING FUNCTIONS
2003 Dec 8 54
Table 7-1: Brownout Options
POWER-ON DETECTION
The Power-On Detect has a function similar to the Brownout Detect, but is designed to work as power initially comes up, before
the power supply voltage reaches a level where the Brownout Detect can function. The POF flag (RSTSRC.4) is set to indicate
an initial power-on condition. The POF flag will remain set until cleared by software by writing ’0’ to the bit. Note that if BOE
(UCFG1.5) is programmed, BOF (RSTSRC.5) will be set when POF is set. If BOE is unprogrammed, BOF is meaningless.
POWER REDUCTION MODES
The P89LPC906/907/908 supports three different power reduction modes as determined by SFR bits PCON.1-0 (see Table ):
BOE
(UCFG1.5)
PMOD1-0
(PCON.1-0)
BOPD
(PCON.5)
BOI
(PCON.4)
EBO
(IEN0.5)
EA
(IEN0.7)
Description
0 (erased)XX XXXX
Brownout disabled. V
DD
operating range is 2.4V-3.6V.
1 (programmed)
11
(total power
down)
XXXX
11
(any mode
other than
total power
down)
1
(brownout
detect
powered
down)
XXX
Brownout disabled. V
DD
operating range is 2.4V-3.6V.
However, BOPD is default to ’0’ upon power-up.
0
(brownout
detect
active)
0
(brownout
detect
generates
reset)
XX
Brownout reset enabled. V
DD
operating range is 2.7V-
3.6V. Upon a brownout reset, BOF (RSTSRC.5) will be
set to indicate the reset source. BOF can be cleared by
writing ’0’ to the bit.
1
(brownout
detect
generates
an
interrupt)
1
(enable
brownout
interrupt)
1
(global
interrupt
enable)
Brownout interrupt enabled. V
DD
operating range is 2.7V-
3.6V. Upon a brownout interrupt, BOF (RSTSRC.5) will
be set. BOF can be cleared by writing ’0’ to the bit.
0 X Both brownout reset and interrupt disabled. V
DD
operating range is 2.4V-3.6V. However, BOF
(RSTSRC.5) will be set when V
DD
falls to the Brownout
Detection trip point. BOF can be cleared by writing ’0’ to
the bit.
X0