Rainbow Electronics ATtiny12 - Manual (Page 20)

20
ATtiny11/12
1006C–09/01
Note: 1. Due to the limited number of clock cycles in the start-up period, it is recommended
that Ceramic Resonator be used.
This table shows the start-up times from reset. From sleep, 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 of WDT oscillator cycles used for each time-out is
shown in Table 10.
The frequency of the watchdog oscillator is voltage dependent as shown in the section
“ATtiny11 Typical Characteristics” on page 58.
Note that the BODLEVEL fuse can be used to select start-up times even if the Brown-
out Detection is disabled (by leaving the BODEN fuse unprogrammed).
The device is shipped with CKSEL3..0 = 0010.
Table 9. ATtiny12 Clock Options and Start-up Times
CKSEL3..0 Clock Source
Start-up Time,
V
CC
= 1.8V,
BODLEVEL
Unprogrammed
Start-up Time,
V
CC
= 2.7V,
BODLEVEL
Programmed
1111 Ext. Crystal/Ceramic Resonator (1) 1K CK 1K CK
1110 Ext. Crystal/Ceramic Resonator (1) 3.6 ms + 1K CK 4.2 ms + 1K CK
1101 Ext. Crystal/Ceramic Resonator (1) 57 ms 1K CK 67 ms + 1K CK
1100 Ext. Crystal/Ceramic Resonator 16K CK 16K CK
1011 Ext. Crystal/Ceramic Resonator 3.6 ms + 16K CK 4.2 ms + 16K CK
1010 Ext. Crystal/Ceramic Resonator 57 ms + 16K CK 67 ms + 16K CK
1001 Ext. Low-frequency Crystal 57 ms + 1K CK 67 ms + 1K CK
1000 Ext. Low-frequency Crystal 57 ms + 32K CK 67 ms + 32K CK
0111 Ext. RC Oscillator 6 CK 6 CK
0110 Ext. RC Oscillator 3.6 ms + 6 CK 4.2 ms + 6 CK
0101 Ext. RC Oscillator 57 ms + 6 CK 67 ms + 6 CK
0100 Int. RC Oscillator 6 CK 6 CK
0011 Int. RC Oscillator 3.6 ms + 6 CK 4.2 ms + 6 CK
0010 Int. RC Oscillator 57 ms + 6 CK 67 ms + 6 CK
0001 Ext. Clock 6 CK 6 CK
0000 Ext. Clock 3.6 ms + 6 CK 4.2 ms + 6 CK
Table 10. Number of Watchdog Oscillator Cycles
BODLEVEL Time-out Number of Cycles
Unprogrammed 3.6 ms (at V
cc
= 1.8V) 256
Unprogrammed 57 ms (at V
cc
= 1.8V) 4K
Programmed 4.2 ms (at V
cc
= 2.7V) 1K
Programmed 67 ms (at V
cc
= 2.7V) 16K