ATMEGA16HVBPRE Datasheet, PDF (27/275 Pages) ATMEL Corporation – 32 x 8 General Purpose Working Registers

ATmega16HVB/32HVB
When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in
Table 9-2 on page 27.
Table 9-2. Start-up times for the calibrated Fast RC Oscillator clock selection
SUT2:0
Start-up Time from
Power-save
Additional Delay from Reset, Typical Values⁽²⁾
000
6 CK
14 CK + 4 ms
001
6 CK
14 CK + 8 ms
010
6 CK
14 CK + 16 ms
011
6 CK
14 CK + 32 ms
100
6 CK
14 CK + 64 ms
101
6 CK
14 CK + 128 ms
110
111⁽¹⁾
6 CK
6 CK
14 CK + 256 ms
14 CK + 512 ms
Notes:
1. The device is shipped with this option selected.
2. The actual value of the added, selectable 4- 512 ms delay depends on the actual frequency of
the ”Ultra Low Power RC Oscillator” on page 27. See Table 9-3 on page 28 and ”Electrical
Characteristics” on page 230
9.2.2
Slow RC Oscillator
The Slow RC Oscillator provides a 131 kHz clock (typical value, refer to section ”Electrical Char-
acteristics” on page 230). This oscillator provides the clock for the CC-ADC module. It can also
be used as a timing reference for run-time calibration of the Fast RC Oscillator and for accu-
rately determining the actual ULP Oscillator frequency, refer to ”OSI – Oscillator Sampling
Interface” on page 29 for details.
To provide good accuracy when used as a timing reference, the Slow RC Oscillator has calibra-
tion bytes stored in the signature address space, refer to section ”Reading the Signature Row
from Software” on page 199 for details. The actual clock period of the Slow RC Oscillator in μs
as a function of temperature is given by:
Slow RC period = -^S---^l--^o---^w------^R----^C------^w-----^o---^r--^d-----^-----^S----^l-^o---^w------^R-----^C------^t-^e----^m-----^p-----^p---^r--^e---^d----ⁱ-^c---^t--ⁱ-^o---ⁿ------^w----^o---^r--^d-----^â‹----⁽-----^{T---------–-------6--T----4----H------O--------T-------)}
1024
9.2.3
where T is the die temperature in Kelvin and T_HOT is the calibration temperature stored in the sig-
nature row. The die temperature can be found using the Voltage ADC, refer to section ”Voltage
ADC – 7-channel General Purpose 12-bit Sigma-Delta ADC” on page 117 for details.
Ultra Low Power RC Oscillator
The Ultra Low Power RC Oscillator (ULP Oscillator) provides a 128 kHz clock (typical value,
refer to section ”Electrical Characteristics” on page 230). This oscillator provides the clock for
the Watchdog Timer and Battery Protection modules. The actual ULP Oscillator frequency
depends on process variations and temperature, see ”Electrical Characteristics” on page 230.
The Oscillator is automatically enabled in all operational modes. It is also enabled during reset.
There are two alternative methods for determining the actual clock period of the ULP Oscillator:
27
8042B–AVR–06/10