attiny167-esxz ATMEL Corporation, attiny167-esxz Datasheet - Page 28

• Manufacturer Part Number: attiny167-esxz
• Description: 8-bit Avr 8-bit Microcontroller Microcontroller With 16k Bytes In-system Programmable Flash And Lin Controller
• Manufacturer: ATMEL Corporation

4.2.5
28
ATtiny167
Low-frequency Crystal Oscillator
Table 4-7.
Notes:
To use a 32.768 kHz watch crystal as the clock source for the device, the low-frequency crystal
oscillator must be selected by setting CKSEL fuses or CSEL field as shown in
24. The crystal should be connected as shown in
Oscillator Application Note for details on oscillator operation and how to choose appropriate val-
ues for C1 and C2.
The 32.768 kHz watch crystal oscillator can be used by the asynchronous timer if the (high-fre-
quency) Crystal Oscillator is not running or if the External Clock is not enabed
”Enable/Disable Clock Source” on page
this low-frequency crystal oscillator.
Figure 4-3.
CKSEL0
CSEL0
1
1
1
1. Flash Fuse bits.
2. CLKSELR register bits.
3. These options should only be used when not operating close to the maximum frequency of the
4. These options are intended for use with ceramic resonators and will ensure frequency stability
5. This setting is only available if RSTDISBL fuse is not set.
(2)
(1)
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
Start-up Times for the Crystal Oscillator Clock Selection (Continued)
Low-frequency Crystal Oscillator Connections
CSUT1..0
SUT1..0
01
10
11
(5)
(1)
(2)
12-22 pF capacitors may be necessary if parasitic
impedance (pads, wires & PCB) is very low.
Start-up Time from
Power-down/save
16K (16384) CK
16K (16384) CK
16K (16384) CK
32.768 KHz
C1=12-22 pF
C2=12-22 pF
31.). The asynchronous timer is then able to start itself
Figure
Additional Delay
14CK + 4.1 ms
14CK + 65 ms
(Vcc = 5.0V)
from Reset
14CK
XTAL2
XTAL1
GND
4-3. Refer to the 32.768 kHz Crystal
Recommended Usage
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator, slowly
rising power
Table 4-1 on page
7728A–AUTO–07/08
(See