ATmega32U4 Atmel Corporation, ATmega32U4 Datasheet - Page 52

• Manufacturer Part Number: ATmega32U4
• Manufacturer: Atmel Corporation

Specifications of ATmega32U4

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 14
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 26
• Ext Interrupts: 13
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 3.3
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 4
• Output Compare Channels: 12
• Input Capture Channels: 2
• Pwm Channels: 8
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

8.0.5
7766F–AVR–11/10
Brown-out Detection
ATmega16U4/ATmega32U4 has an On-chip Brown-out Detection (BOD) circuit for monitoring
the V
BOD can be selected by the BODLEVEL Fuses. The trigger level has a hysteresis to ensure
spike free Brown-out Detection. The hysteresis on the detection level should be interpreted as
V
Table 8-2.
Table 8-3.
When the BOD is enabled, and V
8-5), the Brown-out Reset is immediately activated. When V
(V
expired.
The BOD circuit will only detect a drop in V
ger than t
Figure 8-5.
Symbol
V
t
BOT+
BOD
BOT+
HYST
CC
= V
BODLEVEL 2..0 Fuses
in
level during operation by comparing it to a fixed trigger level. The trigger level for the
BOD
BOT
Figure
+ V
given in
BODLEVEL Fuse Coding
Brown-out Characteristics
Parameter
Brown-out Detector Hysteresis
Min Pulse Width on Brown-out Reset
Brown-out Reset During Operation
INTERNAL
TIME-OUT
111
110
101
100
011
010
001
000
HYST
8-5), the delay counter starts the MCU after the Time-out period t
RESET
RESET
V
CC
/2 and V
Table
8-1.
BOT-
CC
= V
decreases to a value below the trigger level (V
BOT
V
BOT-
Min V
- V
1.8
2.0
2.2
2.4
3.2
3.3
4.0
CC
HYST
BOT
if the voltage stays below the trigger level for lon-
/2.
Typ V
2.0
2.2
2.4
2.6
3.4
3.5
4.3
BOD Disabled
CC
BOT
V
t
TOUT
Min
BOT+
increases above the trigger level
ATmega16/32U4
Typ
50
Max V
2.2
2.4
2.6
2.8
3.6
3.7
4.5
BOT
Max
BOT-
TOUT
in
Units
Units
mV
Figure
V
ns
has
52