P89LPC901 PHILIPS [NXP Semiconductors], P89LPC901 Datasheet - Page 38

• Manufacturer Part Number: P89LPC901
• Description: 8-bit microcontrollers with two-clock 80C51 core 1 kB 3 V Flash with 128-byte RAM
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 12293
Product data
Fig 19. Comparator input and output connections.
(P0.5) CMPREF
(P0.4) CIN1A
(P0.2) CIN2A
V REF
8.20 Internal reference voltage
8.21 Comparator interrupt
8.22 Comparator and power reduction modes
An internal reference voltage generator may supply a default reference when a single
comparator input pin is used. The value of the internal reference voltage, referred to
as V
Each comparator has an interrupt flag contained in its configuration register. This flag
is set whenever the comparator output changes state. The flag may be polled by
software or may be used to generate an interrupt.
The comparators may remain enabled when Power-down or Idle mode is activated,
but the comparators are disabled automatically in Total Power-down mode.
If the comparator interrupt is enabled (except in Total Power-down mode), a change
of the comparator output state will generate an interrupt and wake up the processor. If
the comparator output to a pin is enabled, the pin should be configured in the
push-pull mode in order to obtain fast switching times while in Power-down mode.
The reason is that with the oscillator stopped, the temporary strong pull-up that
normally occurs during switching on a quasi-bidirectional port pin does not take
place.
The comparator consumes power in Power-down and Idle modes, as well as in the
normal operating mode. This fact should be taken into account when system power
consumption is an issue. To minimize power consumption, the user can disable the
comparator via PCONA.5 or put the device in Total Power-down mode.
REF
, is 1.23 V 10%.
CN1
CN2
Rev. 04 — 21 November 2003
Comparator 1
Comparator 2
CO1
CO2
Change Detect
Change Detect
8-bit microcontrollers with two-clock 80C51 core
OE1
OE2
P89LPC901/902/903
CMF1
CMF2
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
CMP1 (P0.6)
CMP2 (P0.0)
EC
002aaa453
Interrupt
38 of 55