Philips P89LPC906, P89LPC908 POWER-ON Detection, Power Reduction Modes, Brownout Options

Philips Semiconductors							User’s Manual - Preliminary -
POWER MONITORING FUNCTIONS							P89LPC906/907/908
Table 7-1: Brownout Options
BOE	PMOD1-0	BOPD	BOI	EBO	EA		Description
(UCFG1.5)	(PCON.1-0)	(PCON.5)	(PCON.4)	(IEN0.5)	(IEN0.7)
0 (erased)	XX	X	X	X	X
	11					Brownout disabled. VDD operating range is 2.4V-3.6V.
	(total power	X	X	X	X
	down)
		1
		(brownout	X	X	X	Brownout disabled. VDD operating range is 2.4V-3.6V.
		detect
		powered				However, BOPD is default to ’0’ upon power-up.
		down)
			0			Brownout reset enabled. VDD operating range is 2.7V-
			(brownout
	≠ 11		detect	X	X	3.6V. Upon a brownout reset, BOF (RSTSRC.5) will be
1 (programmed)						set to indicate the reset source. BOF can be cleared by
	(any mode		generates
						writing ’0’ to the bit.
	other than		reset)
	total power	0		1	1	Brownout interrupt enabled. VDD operating range is 2.7V-
	down)	(brownout	1	(enable	(global
		detect		brownout	interrupt	3.6V. Upon a brownout interrupt, BOF (RSTSRC.5) will
			(brownout			be set. BOF can be cleared by writing ’0’ to the bit.
		active)		interrupt)	enable)
			detect
				0	X	Both brownout reset and interrupt disabled. VDD
			generates
			an			operating range is 2.4V-3.6V. However, BOF
						(RSTSRC.5) will be set when VDD falls to the Brownout
			interrupt)	X	0
						Detection trip point. BOF can be cleared by writing ’0’ to
						the bit.

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 ):

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