ATmega8

The ATmega8A has 3 timers, and 3 PWM channels. There are 6 10-bit ADC channels, and a single analog comparator. The QFP and MLF packages have 2 more ADC channels, for a total of 8. It is pin compatible with the newer, more powerful ATmega88/168/328 devices. It supersedes the ATmega8, which was retired in 2010. It has a wider supply voltage range, and a faster clock than the ATmega8.

The ATmega8 is an early 28-pin device with 8kB of flash. It was the foundation for the Arduino, and is still very popular. The ATmega8A is an improved version, and is the only one available today. By current standards it is a little short of features, but it performs as well as it's more feature-rich relatives.

Power Supply vs. Maximum Frequency

The ATmega8 has a different clock than many other AVR's, featuring an internal clock that runs at 1MHz, 2MHz, 4MHz, and 8MHz, rather than having a divide by 8 fuse. The maximum frequency is 16MHz with an external crystal.

Maximum Frequency Calculator for ATmega8

ATmega8 Features
FeatureATmega8A
Flash 8k
EEPROM 0.5k
RAM 1k
I/O Pins 23
Interrupts 19
USARTS 1
USI 0
SPI 1
TWI 1
ADC Channels 6
RT Counter (w/osc)0
Timers (8-bit) 2
Timers (16-bit) 1
PWM (8-bit) 2
PWM (16-bit) 1
Price (1's) $3.40
CharacteristicValue
Power Consumption (approximate) 1.1mA/MHz
Maximum I/O Current (per pin) 40mA
Maximum I/O Current (all ports) 100mA
Maximum I/O Current (total) 200mA (PDIP)
Maximum I/O Current (total) 400mA (PDIP/QFP/MLF)

ATmega8 Datasheet

Link to ATmega8 datasheet from Atmel's website.

ATmega8 Pinout

ATmega8A-PU pinout ATmega8A-AU pinout

ATmega8 "Minimal" Circuit Diagram

The circuit below shows a programming port, reset circuit, and a crystal oscillator. Any or all of these could be left off and the device would function perfectly well. By default the unit runs from the 8MHz internal RC oscillator divided by 8, for a 1MHz system clock.

ATmega8A minimal schematic diagram