5
7530J–AVR–03/12
Atmel ATmega48/88/168 Automotive
2.3
Comparison Between ATmega48, ATmega88, and ATmega168
The ATmega48, ATmega88 and ATmega168 differ only in memory sizes, boot loader support,
and interrupt vector sizes.
Table 2-2 summarizes the different memory and interrupt vector sizes
for the three devices.
ATmega88 and ATmega168 support a real Read-While-Write Self-Programming mechanism.
There is a separate Boot Loader Section, and the SPM instruction can only execute from there.
In ATmega48, there is no Read-While-Write support and no separate Boot Loader Section. The
SPM instruction can execute from the entire Flash.
2.4
Pin Descriptions
2.4.1
VCC
Digital supply voltage.
2.4.2
GND
Ground.
2.4.3
Port B (PB7..0) XTAL1/
XTAL2/TOSC1/TOSC2
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port B output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscil-
lator amplifier and input to the internal clock operating circuit.
Table 2-1.
Temperature Grade Identification for Automotive Products
Temperature
Identifier
Comments
-40 ; +85
T
Similar to Industrial Temperature Grade but with Automotive
Quality
-40 ; +105
T1
Reduced Automotive Temperature Range
-40 ; +125
Z
Full AutomotiveTemperature Range
Table 2-2.
Memory Size Summary
Device
Flash
EEPROM
RAM
Interrupt Vector Size
ATmega48
4K Bytes
256 Bytes
512 Bytes
1 instruction word/vector
ATmega88
8K Bytes
512 Bytes
1K Bytes
1 instruction word/vector
ATmega168
16K Bytes
512 Bytes
1K Bytes
2 instruction words/vector