Wiblocks --- FAQ

Question

How much current can you source/sink from the ATmega328P pins?

Answer

The microcontroller pins have a specified absolute maximum current of 40mA. The pins are not guaranteed to sink or source more than the listed test condition which is 20mA for a Vcc of 5V and 10mA for a Vcc of 3V. The output voltage specifications and test conditions for VOL and VOH are
Parameter  Condition  Minimum  Typical  Maximum 
VOL IOL=20mA, VCC=5V 0.9V
IOL=10mA, VCC=3V 0.6V
VOH IOL=-20mA, VCC=5V 4.2V
IOL=-10mA, VCC=3V 2.3V

The other limitations on the total current per port and chip are
Maximum IOL
  • IOL should not exceed 40mA.
  • The sum of IOL for ports C0-C5, ADC7, AD6 should not exceeed 100mA.
  • The sum of IOL for ports B0-B5, D5-D7, XTAL1, XTAL2 should not exceeed 100mA.
  • The sum of IOL for ports D0-D4, /RESET should not exceeed 100mA.
Maximum IOH
  • The absolute maximum IOH is 40mA.
  • The sum of IOH for ports C0-C5, D0-D4, ADC7, /RESET should not exceeed 150mA.
  • The sum of IOH for ports B0-B5, D5-D7, ADC6, XTAL1, XTAL2 should not exceeed 150mA.
  • Max ICC The absolute maximum ICC is 200mA.

References

Atmel. (2009). 8-bit AVR Microcontroller with 4/8/16/32K Bytes In-System Programmable Flash., pages 313-314. (Retrieved March 14, 2009, from doc8025.pdf)