ATmega16U4/32U4 Datasheet, Pinout, Minimal Circuit

The ATmegaXXU4 devices are a different approach to a USB enabled AVR. They still have the USB 2.0 full-speed engine, but it has larger buffers, and the other peripherals found on AVRs are still available. Rather than a USB converter, they turn out to be a great USB enabled microcontroller.

Still, the main feature of the ATmega8U2/16U2/32U2 MCU's is the USB 2.0 engine. It is the basis for the Leonardo and Sparkfun Pro Micro boards. There is an ADC section, and two full 8-bit I/O ports. These devices make it possible to have USB enabled applications with a single MCU.

Power Supply vs. Maximum Frequency

The calculator below provides a way to find the maximum operating frequency for any valid power supply voltage (2.7 to 5.5). Enter the power supply voltage and click "Calculate Max Frequency" to find the ATmega32U4's specified maximum clock speed at your Vcc.

Maximum Frequency Calculator for ATmega16U4/32U4

ATmega16U4/32U4 Features
Feature16U432U4
Flash 16k32k
EEPROM 0.5k1k
RAM 0.5k1k
I/O Pins 22
Interrupts 29
USARTS 1
USI 0
SPI 1
TWI 0
ADC Channels 0
RT Counter (w/osc)0
Timers (8-bit) 1
Timers (16-bit) 1
PWM (8-bit) 2
PWM (16-bit) 3
USB 2.0 Engine 1
Price (1's) $5.46$6.18
CharacteristicValue
Power Consumption (approximate) 5.5mA + (0.5/MHz)
Maximum I/O Current (per pin) 40mA
Maximum I/O Current (all ports) 100mA(low)/150mA(high)
Maximum I/O Current (total) 200mA (PDIP)
Maximum I/O Current (total)400mA (PDIP/QFP/MLF)

ATmega16U4/32U4 Datasheet

Link to ATmega16U4/32U4 datasheet from Atmel's website.

ATmega16U4/32U4 Pinout

ATmega32U4-MU pinout