ATA5771 ATMEL Corporation, ATA5771 Datasheet - Page 92

• Manufacturer Part Number: ATA5771
• Manufacturer: ATMEL Corporation

8.2.2
8.2.3
40
ATtiny24/44/84
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.
ATtiny24/44/84 has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
during operation by comparing it to a 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
V
When the BOD is enabled, and V
8-5 on page
trigger level (V
out period t
The BOD circuit will only detect a drop in V
ger than t
Figure 8-5.
BOT
+ V
INTERNAL
TIME-OUT
HYST
BOD
RESET
RESET
TOUT
CC
V
40), the Brown-out Reset is immediately activated. When V
/2 and V
given in
CC
External Reset During Operation
Brown-out Reset During Operation
BOT+
has expired.
in
BOT-
Figure 8-5 on page
“System and Reset Characteristics” on page
= V
BOT
- V
CC
“System and Reset Characteristics” on page
V
HYST
decreases to a value below the trigger level (V
BOT-
/2.
40), the delay counter starts the MCU after the Time-
CC
if the voltage stays below the trigger level for lon-
V
t
TOUT
BOT+
179.
TOUT
CC
– has expired.
RST
increases above the
– on its positive
179) will gener-
8006G–AVR–01/08
BOT-
in
CC
BOT+
Figure
level
=