6
7530J–AVR–03/12
Atmel ATmega48/88/168 Automotive
Depending on the clock selection fuse settings, PB7 can be used as output from the inverting
Oscillator amplifier.
If the Internal Calibrated RC Oscillator is used as chip clock source, PB7..6 is used as TOSC2..1
input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.
2.4.4
Port C (PC5..0)
Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
PC5..0 output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
2.4.5
PC6/RESET
If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical char-
acteristics of PC6 differ from those of the other pins of Port C.
If the RSTDISBL Fuse is unprogrammed, PC6 is used as a 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.
to generate a Reset.
2.4.6
Port D (PD7..0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port D output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
2.4.7
AV
CC
AV
CC is the supply voltage pin for the A/D Converter, PC3..0, and ADC7..6. It should be exter-
nally connected 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. Note that PC6..4 use digital supply voltage, VCC.
2.4.8
AREF
AREF is the analog reference pin for the A/D Converter.
2.4.9
ADC7..6 (TQFP and QFN Package Only)
In the TQFP and QFN package, ADC7..6 serve as analog inputs to the A/D converter. These
pins are powered from the analog supply and serve as 10-bit ADC channels.