ATMEGA645A-AU Atmel, ATMEGA645A-AU Datasheet - Page 47

• Manufacturer Part Number: ATMEGA645A-AU
• Description: IC MCU AVR 64K FLASH 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA645A-AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K 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-TQFP
• Processor Series: ATmega
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: SPI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 54
• Number Of Timers: 3
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

10.2.1
8285B–AVR–03/11
Power-on Reset
ATmega165A/165PA/325A/325PA/3250A/3250PA/6
Figure 10-1. Reset Logic
A Power-on Reset (POR) pulse is generated by an On-chip detection circuit. The detection level
is defined in
V
well as to detect a failure in supply voltage.
A Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reaching the
Power-on Reset threshold voltage invokes the delay counter, which determines how long the
device is kept in RESET after V
when V
Figure 10-2. MCU Start-up, RESET Tied to V
CC
is below the detection level. The POR circuit can be used to trigger the start-up Reset, as
INTERNAL
TIME-OUT
BODLEVEL [2..0]
CC
RESET
RESET
V
decreases below the detection level.
CC
”System and Reset Characteristics” on page
Pull-up Resistor
JTAG Reset
Register
FILTER
SPIKE
V
V
POT
RST
CC
t
TOUT
CKSEL[3:0]
rise. The RESET signal is activated again, without any delay,
Power-on Reset
Reset Circuit
SUT[1:0]
Brown-out
Watchdog
Oscillator
Generator
Circuit
Clock
CK
CC
Register (MCUSR)
MCU Status
DATA BUS
Delay Counters
326. The POR is activated whenever
TIMEOUT
47