Datasheet

10
8284D–AVR–6/11
ATmega169A/PA/329A/PA/3290A/PA/649A/P/6490A/P
bility. As inputs, Port J pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port J pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port J also serves the functions of various special features of the ATmega3290PA/6490P as
listed on page 90.
2.3.12 RESET
Reset input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in ”System and Reset
Characteristics” on page 353. Shorter pulses are not guaranteed to generate a reset.
2.3.13 XTAL1
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
2.3.14 XTAL2
Output from the inverting Oscillator amplifier.
2.3.15 AVCC
AVCC is the supply voltage pin for Port F and the A/D Converter. It should be externally con-
nected to V
CC
, even if the ADC is not used. If the ADC is used, it should be connected to V
CC
through a low-pass filter.
2.3.16 AREF
This is the analog reference pin for the A/D Converter.
2.3.17 LCDCAP
An external capacitor (typical > 470 nF) must be connected to the LCDCAP pin as shown in Fig-
ure 24-2, if the LCD module is enabled and configured to use internal power. This capacitor acts
as a reservoir for LCD power (V
LCD
). A large capacitance reduces ripple on V
LCD
but increases
the time until V
LCD
reaches its target value.