ATMEGA325A-MU Atmel, ATMEGA325A-MU Datasheet - Page 49

• Manufacturer Part Number: ATMEGA325A-MU
• Description: IC MCU AVR 32K FLASH 64VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA325A-MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

10.2.3
10.2.4
8285B–AVR–03/11
Brown-out Detection
Watchdog Reset
ATmega165A/165PA/325A/325PA/3250A/3250PA/6
ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/6450A/6450P has an On-chip
Brown-out Detection (BOD) circuit for monitoring the V
to a fixed trigger level. The trigger level for the 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
V
in
trigger level (V
t
The BOD circuit will only detect a drop in V
ger than t
Figure 10-5. Brown-out Reset During Operation
When the Watchdog times out, it will generate a short reset pulse of one CK cycle duration. On
the falling edge of this pulse, the delay timer starts counting the Time-out period t
page 50
Figure 10-6. Watchdog Reset During Operation
TOUT
HYST
Figure
has expired.
/2.When the BOD is enabled, and V
for details on operation of the Watchdog Timer.
BOD
10-5), the Brown-out Reset is immediately activated. When V
CC
given in
BOT+
INTERNAL
TIME-OUT
RESET
RESET
in
V
CC
”System and Reset Characteristics” on page
Figure
10-5), the delay counter starts the MCU after the Time-out period
V
CK
BOT-
CC
CC
decreases to a value below the trigger level (V
if the voltage stays below the trigger level for lon-
BOT+
CC
= V
level during operation by comparing it
BOT
V
t
TOUT
BOT+
+ V
326.
HYST
CC
/2 and V
increases above the
BOT-
TOUT
. Refer to
= V
BOT
BOT-
49
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