259
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P [DATASHEET]
8285E–AVR–02/2013
Note:
1. The SPIEN Fuse is not accessible in serial programming mode.
4. Never ship a product with the OCDEN Fuse programmed regardless of the setting of Lock bits and JTAGEN Fuse.
A programmed OCDEN Fuse enables some parts of the clock system to be running in all sleep modes. This may
increase the power consumption.
5. If the JTAG interface is left unconnected, the JTAGEN fuse should if possible be disabled. This to avoid static cur-
rent at the TDO pin in the JTAG interface.
Note:
1. The default value of SUT1:0 results in maximum start-up time for the default clock source. See
Table 28-13 on2. The default setting of CKSEL3:0 results in internal RC Oscillator @ 8MHz. See
Table 9-10 on page 32 for details.
details.
The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if Lock bit1 (LB1) is
programmed. Program the Fuse bits before programming the Lock bits.
27.2.1
Latching of Fuses
The fuse values are latched when the device enters programming mode and changes of the fuse values will have
no effect until the part leaves Programming mode. This does not apply to the EESAVE Fuse which will take effect
once it is programmed. The fuses are also latched on Power-up in Normal mode.
Table 27-4.
Fuse High byte.
Fuse High byte
Bit no.
Description
Default value
7
Enable OCD
1 (unprogrammed, OCD disabled)
6
Enable JTAG
0 (programmed, JTAG enabled)
5
Enable Serial Program and Data
Downloading
0 (programmed, SPI prog.
enabled)
4
Watchdog Timer always on
1 (unprogrammed)
EESAVE
3
EEPROM memory is preserved
through the Chip Erase
1 (unprogrammed, EEPROM not
preserved)
BOOTSZ1
2
BOOTSZ0
1
BOOTRST
0
Select Reset Vector
1 (unprogrammed)
Table 27-5.
Fuse Low byte.
Fuse Low byte
Bit no.
Description
Default value
7
Divide clock by 8
0 (programmed)
6
Clock output
1 (unprogrammed)
SUT1
5
Select start-up time
SUT0
4
Select start-up time
CKSEL3
3
Select Clock source
CKSEL2
2
Select Clock source
CKSEL1
1
Select Clock source
CKSEL0
0
Select Clock source