P89LPC901FD datasheet(9/55 Pages) PHILIPS

9 / 55 page

Philips Semiconductors

P89LPC901/902/903

8-bit microcontrollers with two-clock 80C51 core

Product data

Rev. 04 — 21 November 2003

9 of 55

9397 750 12293

P3.0 - P3.1

2, 3

I/O

Port 3: Port 3 is an I/O port with a user-conﬁgurable output types. During reset Port 3

latches are conﬁgured in the input only mode with the internal pull-up disabled. The

operation of port 3 pins as inputs and outputs depends upon the port conﬁguration

selected. Each port pin is conﬁgured independently. Refer to Section 8.12.1 “Port

conﬁgurations” and Table 13 “DC electrical characteristics” for details.

All pins have Schmitt triggered inputs.

Port 3 also provides various special functions as described below:

I/O

P3.0 — Port 3 bit 0.

XTAL2 — Output from the oscillator ampliﬁer (when a crystal oscillator option is

selected via the FLASH conﬁguration).

CLKOUT — CPU clock divided by 2 when enabled via SFR bit (ENCLK - TRIM.6). It

can be used if the CPU clock is the internal RC oscillator, Watchdog oscillator or

external clock input, except when XTAL1/XTAL2 are used to generate clock source

for the real time clock/system timer.

I/O

P3.1 — Port 3 bit 1.

XTAL1 — Input to the oscillator circuit and internal clock generator circuits (when

selected via the FLASH conﬁguration). It can be a port pin if internal RC oscillator or

Watchdog oscillator is used as the CPU clock source, and if XTAL1/XTAL2 are not

used to generate the clock for the real time clock/system timer.

VSS

Ground: 0 V reference.

VDD

Power Supply: This is the power supply voltage for normal operation as well as Idle

and Power-down modes.

Table 3:

P89LPC901 pin description…continued

Symbol

Type

Description

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