ATtiny15L
14
Note: 1. The Power-on Reset will not work unless the supply voltage has been below V
POT
(falling).
Notes: 1. On power-up, the start-up time is increased with typical 0.6 ms.
2. “1” means programmed, “0” means unprogrammed.
Table 5 shows the start-up times from reset. When the CPU wakes up from power-down, only the clock-counting part of the
start-up time is used. The watchdog oscillator is used for timing the real-time part of the start-up time. The number watch-
dog oscillator cycles used for each time-out is shown in Table 6.
The frequency of the watchdog oscillator is voltage dependent as shown in the Electrical Characteristics section on
page 56. The device is shipped with CKSEL = “00”.
Table 4. Reset Characteristics (V
CC
= 5.0V)
Symbol Parameter Condition Min Typ Max Units
V
POT
Power-on Reset Threshold Voltage (rising) BOD disabled 1.0 1.4 1.8 V
BOD enabled 1.7 2.2 2.7 V
Power-on Reset Threshold Voltage (falling)
(1)
BOD disabled 0.4 0.6 0.8 V
BOD enabled 1.7 2.2 2.7 V
V
RST
RESET Pin Threshold Voltage - - 0.85V
CC
V
V
BOT
Brown-out Reset Threshold Voltage (BODLEVEL = 1) 2.6 2.7 2.8 V
(BODLEVEL = 0) 3.8 4.0 4.2 V
Table 5. Reset Delay Selections
(1)
BODEN
(2)
CKSEL [1:0]
(2)
Start-up Time,
t
TOUT
at V
CC
= 2.7V
Start-up Time,
t
TOUT
at V
CC
= 5.0V Recommended Usage
x 00 256 ms + 18 CK 64 ms + 18 CK BOD disabled, slowly rising power
x 01 256 ms + 18 CK 64 ms + 18 CK BOD disabled, slowly rising power
x 10 16 ms + 18 CK 4 ms + 18 CK BOD disabled, quickly rising power
1 11 18 CK + 32 µs 18 CK + 8 µs BOD disabled
0 11 18 CK + 128 µs 18 CK + 32 µs BOD enabled
Table 6. Number of Watchdog Oscillator Cycles
V
CC
Conditions Time-out Number of Cycles
2.7V 32 µs 8
2.7V 128 µs 32
2.7V 16 ms 4K
2.7V 256 ms 64K
5.0V 8 µs 8
5.0V 32 µs 32
5.0V 4 ms 4K
5.0V 64 ms 64K
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