ATMEGA328P-20PU Atmel, ATMEGA328P-20PU Datasheet - Page 48

• Manufacturer Part Number: ATMEGA328P-20PU
• Manufacturer: Atmel

Specifications of ATMEGA328P-20PU

• Cpu Family: ATmega
• Device Core: AVR
• Device Core Size: 8b
• Frequency (max): 20MHz
• Interface Type: SPI/TWI/USART
• Program Memory Type: Flash
• Program Memory Size: 32KB
• Total Internal Ram Size: 2KB
• # I/os (max): 23
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 6-chx10-bit
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Through Hole
• Pin Count: 28
• Package Type: PDIP
• Lead Free Status / Rohs Status: Compliant

10.4
10.5
8025K–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
ATmega48P/88P/168P has an On-chip Brown-out Detection (BOD) circuit for monitoring the
V
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
value below the trigger level (V
ately activated. When V
the delay counter starts the MCU after the Time-out period t
The BOD circuit will only detect a drop in V
ger than t
CC
BOT
level during operation by comparing it to a fixed trigger level. The trigger level for the BOD
INTERNAL
TIME-OUT
+ V
RESET
RESET
HYST
BOD
V
CC
CC
/2 and V
given in
BOT-
”System and Reset Characteristics” on page
CC
= V
increases above the trigger level (V
V
”System and Reset Characteristics” on page
POT
BOT
BOT-
- V
in
HYST
Figure 10-5 on page
/2.When the BOD is enabled, and V
CC
Table 27-6 on page
if the voltage stays below the trigger level for lon-
V
RST
t
TOUT
ATmega48P/88P/168P
TOUT
49), the Brown-out Reset is immedi-
TOUT
– has expired. The External Reset
BOT+
has expired.
292.
RST
313.
in
– on its positive edge, the
Figure 10-5 on page
313) will generate a
CC
decreases to a
BOT+
49),
48
=