Philips P89LPC903 - Manual (Page 56)

Philips Semiconductors User’s Manual - Preliminary -
P89LPC901/902/903
POWER MONITORING FUNCTIONS
2003 Dec 8
56
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.
BOE
(UCFG1.5)
PMOD1-0
(PCON.1-0)
BOPD
(PCON.5)
BOI
(PCON.4)
EBO
(IEN0.5)
EA
(IEN0.7)
Description
0 (erased) XX X X X X
Brownout disabled. V
DD
operating range is 2.4V-3.6V.
1 (programmed)
11 (total
power down)
X X X X
≠ 11(any
mode other
than total
power down)
1
(brownout
detect
powered
down)
X X X
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)
X X
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.
X 0
Table 7-1: Brownout Options.