ATMEGA32U4-AUR Atmel, ATMEGA32U4-AUR Datasheet - Page 253

• Manufacturer Part Number: ATMEGA32U4-AUR
• Description: MCU AVR 16K FLASH 16MHZ 44TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA32U4-AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 26
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2.5K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

21. USB controller
21.1
21.2
7766F–AVR–11/10
Features
Block Diagram
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•
•
•
•
The USB controller provides the hardware to interface a USB link to a data flow stored in a dou-
ble port memory (DPRAM).
The USB controller requires a 48 MHz ±0.25% reference clock (for Full-Speed operation), which
is the output of an internal PLL. The on-chip PLL generates the internal high frequency (48 MHz)
clock for USB interface. The PLL clock input can be configured to use external low-power crystal
oscillator, external source clock or internal RC (see Section “Crystal-less operation”, page 256).
The 48MHz clock is used to generate a 12 MHz Full-speed (or 1.5 MHz Low-Speed) bit clock
from the received USB differential data and to transmit data according to full or low speed USB
device tolerance. Clock recovery is done by a Digital Phase Locked Loop (DPLL) block, which is
compliant with the jitter specification of the USB bus.
To comply with the USB Electrical specification, USB buffers (D+ or D-) should be powered
within the 3.0 to 3.6V range. As ATmega16U4/ATmega32U4 can be powered up to 5.5V, an
internal regulator provides the USB buffers power supply.
Figure 21-1. USB controller Block Diagram overview
Supports full-speed and low-speed Device role
Complies with USB Specification v2.0
Supports ping-pong mode (dual bank)
832 bytes of DPRAM:
Crystal-less operation for low-speed mode
– 1 endpoint 64 bytes max (default control endpoint)
– 1 endpoints of 256 bytes max, (one or two banks)
– 5 endpoints of 64 bytes max, (one or two banks)
UCAP
VBUS
D-
D+
USB Regulator
Recovery
DPLL
Clock
UVCC
Interface
USB
clk
48MHz
Div-by-2
AVCC
PLL
&
clk
8MHz
USB DPRAM
ATmega16/32U4
XT1
PLL clock
Prescaler
On-Chip
Clock Mux
IntRC
CPU
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