Philips P89LPC907 用户手册

2003 Dec 8     

54

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.

The P89LPC906/907/908 supports three different power reduction modes as determined by SFR bits PCON.1-0 (see Table ):

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