attiny15l ATMEL Corporation, attiny15l Datasheet - Page 17

• Manufacturer Part Number: attiny15l
• Description: Attiny15l 8-bit Microcontroller With 1k Byte Flash
• Manufacturer: ATMEL Corporation

Brown-out Detection
Watchdog Reset
1187H–AVR–09/07
ATtiny15L has an On-chip Brown-out Detection (BOD) circuit for monitoring the V
level during the operation. The BOD circuit can be enabled/disabled by the fuse
BODEN. When BODEN is enabled (BODEN programmed), and V
the trigger level, the Brown-out Reset is immediately activated. When V
above the trigger 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 5. The trigger
level for the BOD can be selected by the fuse BODLEVEL to be 2.7V (BODLEVEL
unprogrammed), or 4.0V (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 3
Figure 16. Brown-out Reset during Operation
Note:
When the Watchdog times out, it will generate a short reset pulse of one CK cycle dura-
tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period
t
Figure 17. Watchdog Reset during Operation
TOUT
. Refer to page 34 for details on operation of the Watchdog Timer.
1. The hysteresis on V
INTERNAL
TIME-OUT
RESET
RESET
V
CC
µs
for trigger level 4.0V, 7
BOT
: V
1 CK Cycle
V
BOT+
BOT-
= V
BOT
CC
µs
+ 25 mV, V
if the voltage stays below the trigger level
for trigger level 2.7V (typical values).
(1)
BOT-
V
t
TOUT
BOT+
= V
BOT
- 25 mV.
CC
ATtiny15L
decreases below
CC
increases
17
CC