ATMEGA8A-AUR Atmel, ATMEGA8A-AUR Datasheet - Page 39

• Manufacturer Part Number: ATMEGA8A-AUR
• Description: MCU AVR 8KB FLASH 16MHZ 32TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8A-AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

10.2.2
10.2.3
8159D–AVR–02/11
External Reset
Brown-out Detection
Figure 10-3. MCU Start-up, RESET Extended Externally
An External Reset is generated by a low level on the RESET pin. Reset pulses longer than the
minimum pulse width (see
running. Shorter pulses are not guaranteed to generate a reset. When the applied signal
reaches the Reset Threshold Voltage – V
MCU after the time-out period t
Figure 10-4. External Reset During Operation
ATmega8A has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
ing operation by comparing it to a fixed trigger level. The trigger level for the BOD can be
selected by the fuse BODLEVEL to be 2.7V (BODLEVEL unprogrammed), or 4.0V (BODLEVEL
programmed). 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
The BOD circuit can be enabled/disabled by the fuse BODEN. When the BOD is enabled
(BODEN programmed), and V
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
BOT
BOT+
INTERNAL
TIME-OUT
- V
in
RESET
HYST
RESET
BOD
V
Figure
CC
CC
/2.
given in
10-5), the delay counter starts the MCU after the time-out period t
Table 25-3 on page
Table 25-3 on page
V
POT
CC
TOUT
decreases to a value below the trigger level (V
has expired.
247.
RST
CC
if the voltage stays below the trigger level for lon-
on its positive edge, the delay counter starts the
247) will generate a reset, even if the clock is not
V
RST
t
TOUT
CC
BOT+
increases above the trigger level
= V
BOT
+ V
ATmega8A
HYST
BOT-
/2 and V
in
CC
Figure 10-
level dur-
TOUT
BOT-
has
39
=