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© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual Rev. 02 — 23 May 2005 33 of 133
Philips Semiconductors
UM10109
P89LPC932A1 User manual
[1] Cannot be used with operation above 12 MHz as this requires V
DD
of 3.0 V or above.
5.2 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 a
logic 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.
5.3 Power reduction modes
The P89LPC932A1 supports three different power reduction modes as determined by
SFR bits PCON[1:0] (see Tabl e 12
).
Table 11: Brownout options
[1]
BOE
(UCFG1.5)
PMOD1/
PMOD0
(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 2.4 V to 3.6 V.
1(program
med)
11 (total
power-down)
XXXX
≠ 11 (any mode
other than total
power-down)
1 (brownout
detect
power-down)
X X X Brownout disabled. V
DD
operating range is 2.4 V to 3.6 V.
However, BOPD is default to
logic 0 upon power-up.
0 (brownout
detect active)
0 (brownout
detect
generates
reset)
X X Brownout reset enabled. V
DD
operating range is 2.7 V to 3.6 V.
Upon a brownout reset, BOF
(RSTSRC.5) will be set to
indicate the reset source. BOF
can be cleared by writing a
logic 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 2.7 V to 3.6 V.
Upon a brownout interrupt, BOF
(RSTSRC.5) will be set. BOF can
be cleared by writing a logic 0 to
the bit.
0 X Both brownout reset and
interrupt disabled. V
DD
operating
range is 2.4 V to 3.6 V. However,
BOF (RSTSRC.5) will be set
when V
DD
falls to the Brownout
Detection trip point. BOF can be
cleared by writing a logic 0 to the
bit.
X0