AT90LS8535-4PC datasheet(5/127 Pages) ATMEL

5 / 127 page

AT90S/LS8535

1041H–11/01

current if the pull-up resistors are activated. Two Port C pins can alternatively be used

as oscillator for Timer/Counter2.

The Port C pins are tri-stated when a reset condition becomes active, even if the clock is

not running.

Port D (PD7..PD0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors. The Port D output

buffers can sink 20 mA. As inputs, Port D pins that are externally pulled low will source

current if the pull-up resistors are activated.

Port D also serves the functions of various special features of the AT90S8535 as listed

on page 86.

The Port D pins are tri-stated when a reset condition becomes active, even if the clock is

not running.

RESET

Reset input. An external reset is generated by a low level on the RESET pin. Reset

pulses longer than 50 ns will generate a reset, even if the clock is not running. Shorter

pulses are not guaranteed to generate a reset.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

AVCC

AVCC is the supply voltage pin for Port A and the A/D Converter. If the ADC is not used,

this pin must be connected to VCC. If the ADC is used, this pin must be connected to

VCC via a low-pass filter. See page 68 for details on operation of the ADC.

AREF

AREF is the analog reference input for the A/D Converter. For ADC operations, a volt-

age in the range 2V to AVCC must be applied to this pin.

AGND

Analog ground. If the board has a separate analog ground plane, this pin should be con-

nected to this ground plane. Otherwise, connect to GND.

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