attiny261a-xu ATMEL Corporation, attiny261a-xu Datasheet - Page 41

• Manufacturer Part Number: attiny261a-xu
• Description: 8-bit Avr Microcontroller With 2/4/8k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

8.2.2
8.2.3
8197B–AVR–01/10
External Reset
Brown-out Detection
An External Reset is generated by a low level on the RESET pin if enabled. Reset pulses longer
than the minimum pulse width (see
ate a 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
edge, the delay counter starts the MCU after the Time-out period – t
Figure 8-4.
A Brown-out Detection (BOD) circuit monitors the V
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
When the BOD is enabled, and V
8-5), the Brown-out Reset is immediately activated. When V
(V
expired.
The BOD circuit will only detect a drop in V
ger than t
Figure 8-5.
BOT+
in
BOD
Figure
CC
given in
External Reset During Operation
Brown-out Reset During Operation
INTERNAL
TIME-OUT
8-5), the delay counter starts the MCU after the Time-out period t
RESET
RESET
V
CC
“System and Reset Characteristics” on page
CC
“System and Reset Characteristics” on page
decreases to a value below the trigger level (V
V
BOT-
BOT+
CC
= V
if the voltage stays below the trigger level for lon-
BOT
CC
+ V
level during operation by comparing it to a
HYST
CC
/2 and V
V
t
TOUT
BOT+
increases above the trigger level
187.
TOUT
BOT-
– has expired.
= V
RST
BOT
– on its positive
187) will gener-
- V
BOT-
HYST
TOUT
in
/2.
Figure
has
41