Datasheet

ATmega48/88/168 Automotive [DATASHEET]

7530K–AVR–07/14

The CKDIV8 fuse determines the initial value of the CLKPS bits. If CKDIV8 is unprogrammed, the CLKPS bits will be reset to

“0000”. If CKDIV8 is programmed, CLKPS bits are reset to “0011”, giving a division factor of 8 at start up. This feature should

be used if the selected clock source has a higher frequency than the maximum frequency of the device at the present

operating conditions. Note that any value can be written to the CLKPS bits regardless of the CKDIV8 fuse setting. The

application software must ensure that a sufficient division factor is chosen if the selected clock source has a higher

frequency than the maximum frequency of the device at the present operating conditions. The device is shipped with the

CKDIV8 fuse programmed.

Table 6-14. Clock Prescaler Select

CLKPS3 CLKPS2 CLKPS1 CLKPS0 Clock Division Factor

0 0 0 0 1

0 0 0 1 2

0 0 1 0 4

0 0 1 1 8

0 1 0 0 16

0 1 0 1 32

0 1 1 0 64

0 1 1 1 128

1 0 0 0 256

1 0 0 1 Reserved

1 0 1 0 Reserved

1 0 1 1 Reserved

1 1 0 0 Reserved

1 1 0 1 Reserved

1 1 1 0 Reserved

1 1 1 1 Reserved