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- 14 -
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SX20AC/SX28AC
5.2 FUSEX Word (Read/Program via Programming Command)
5.3 DEVICE Word (Hard-Wired Read-Only)
IRC
TRIM2
PINS
IRC
TRIM1
IRC
TRIM0
OPTIONX/
STACKX
CF
BOR1
BOR0
BOR
TRIM1
BOR
TRIM0
BP1
BP0
Bit 11
Bit 7
Bit 3
Bit 0
IRCTRIM2:
IRCTRIM0
Internal RC oscillator trim bits. This 3-bit field adjusts the operation of the internal RC oscillator to make
it operate within the target frequency range 4 MHz plus or minus 8%. Parts are shipped from the factory
untrimmed. The device relies on the programming toll to provide the trimming function.
000b = minimum frequency
111b = maximum frequency
each step about 3%
PINS
Selects the number of pins.
0 = 18/20 pins
1 = 28 pins
OPTIONX/
STACKX
OPTION Register Extension and Stack Extension. Set to 1 to disable the programmability of bit 6 and
bit 7 in the OPTION register, the RTW and RTE_IE bits (in other words, to force these two bits to 1) and
to limit the program stack size to two locations. Clear to 0 to enable programming of the RTW and
RTE_IE bits in the OPTION register, and to extend the stack size to eight locations.
CF
Active low makes carry bit input to ADD and SUB instructions.
BOR1: BOR0 Brown-Out Reset;These bits enable or disable the brown-out reset function and set the brown-out
threshold voltage as follows:
00b = 4.2V ± 10%
01b = 2.6V ± 10%
10b = 2.2V ± 10%
11b = Brown-Out disabled
BORTRIM1:
BORTRIM0
Brown-Out trim bits (parts are shipped out of factory untrimmed).
BP1:BP0
Configure Program and Data Memory Size:
00b =
1 page, 1 bank
01b =
2 pages, 1 bank
10b =
4 pages, 4 banks
11b =
4 pages, 8 banks (default configuration)
1
1
1
1
1
1
0
0
1
1
1
0
Bit 11
Bit7
Bit 3
Bit 0