ATTINY15 ATMEL [ATMEL Corporation], ATTINY15 Datasheet - Page 16

• Manufacturer Part Number: ATTINY15
• Manufacturer: ATMEL [ATMEL Corporation]

External Reset
Brown-out Detection
16
ATtiny15L
Figure 14. MCU Start-up, RESET Extended Externally
An External Reset is generated by a low-level on the RESET pin. Reset pulses longer
than 500 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 15. External Reset during Operation
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
INTERNAL
TIME-OUT
RESET
RESET
VCC
TOUT
RST
has expired.
) on its positive edge, the delay timer starts the MCU after the Time-out
µs
for trigger level 4.0V, 7
V
POT
V
CC
µs
RST
if the voltage stays below the trigger level
for trigger level 2.7V (typical values).
t
TOUT
CC
decreases below
CC
increases
1187D–12/01
CC