attiny11 ATMEL Corporation, attiny11 Datasheet - Page 27

• Manufacturer Part Number: attiny11
• Description: 8-bit Microcontroller With 1k Byte Flash
• Manufacturer: ATMEL Corporation

External Reset
Brown-out Detection
(ATtiny12)
1006F–AVR–06/07
An external reset is generated by a low level on the RESET pin. Reset pulses longer
than 50 ns will generate 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
period (t
Figure 19. External Reset during Operation
ATtiny12 has an on-chip brown-out detection (BOD) circuit for monitoring the V
during the operation. The BOD circuit can be enabled/disabled by the fuse BODEN.
When BODEN is enabled (BODEN programmed), and V
level, the brown-out reset is immediately activated. When V
ger level, the brown-out reset is deactivated after a delay. The delay is defined by the
user in the same way as the delay of POR signal, in Table 14. The trigger level for the
BOD can be selected by the fuse BODLEVEL to be 1.8V (BODLEVEL unprogrammed),
or 2.7V (BODLEVEL programmed). The trigger level has a hysteresis of 50 mV to
ensure spike-free brown-out detection.
The BOD circuit will only detect a drop in V
for longer than 7 µs for trigger level 2.7V, 24 µs for trigger level 1.8V (typical values).
Figure 20. Brown-out Reset during Operation (ATtiny12)
Note:
INTERNAL
TIME-OUT
INTERNAL
TIME-OUT
RESET
RESET
RESET
RESET
V
CC
V
The hysteresis on V
TOUT
CC
RST
) has expired.
– on its positive edge, the delay timer starts the MCU after the Time-out
V
RST
BOT
: V
BOT +
V
BOT-
= V
t
BOT
TOUT
+ 25 mV, V
CC
if the voltage stays below the trigger level
BOT-
= V
CC
BOT
decreases below the trigger
CC
V
t
TOUT
- 25 mV.
BOT+
increases above the trig-
ATtiny11/12
CC
level
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