A000046 Arduino, A000046 Datasheet - Page 48

• Manufacturer Part Number: A000046
• Description: MCU, MPU & DSP Development Tools Uno
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000046

• Processor To Be Evaluated: ATmega328
• Interface Type: USB, I2C, SPI
• Dimensions: 2.7 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega328

10.4
10.5
8161D–AVR–10/09
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
reset, even if the clock is not running. Shorter pulses are not guaranteed to generate a reset.
When the applied signal reaches the Reset Threshold Voltage – V
delay counter starts the MCU after the Time-out period – t
can be disabled by the RSTDISBL fuse, see
Figure 10-4. External Reset During Operation
ATmega48PA/88PA/168PA/328P has an On-chip Brown-out Detection (BOD) circuit for moni-
toring the V
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
decreases to a value below the trigger level (V
Reset is immediately activated. When V
5 on page
The BOD circuit will only detect a drop in V
ger than t
BOT+
INTERNAL
TIME-OUT
= V
RESET
RESET
BOD
V
49), the delay counter starts the MCU after the Time-out period t
BOT
CC
CC
CC
given in
level during operation by comparing it to a fixed trigger level. The trigger level for
+ V
HYST
”System and Reset Characteristics” on page
/2 and V
V
”System and Reset Characteristics” on page
POT
BOT-
ATmega48PA/88PA/168PA/328P
= V
CC
BOT
increases above the trigger level (V
CC
Table 27-7 on page
- V
if the voltage stays below the trigger level for lon-
V
BOT-
RST
HYST
t
TOUT
in
/2.When the BOD is enabled, and V
Figure 10-5 on page
TOUT
– has expired. The External Reset
296.
RST
318.
– on its positive edge, the
TOUT
318) will generate a
49), the Brown-out
BOT+
has expired.
in
Figure 10-
48
CC