© 1999 Scenix Semiconductor, Inc. All rights reserved. - 13 - www.scenix.com SX18AC  / SX20AC / SX28AC 5.2 FUSEX Word (Read/Program via Programming Command) 5.3 DEVICE Word (Hard-Wired Read-Only) IRCTRI M2 PINS IRCTRI M1 IRCTRI M0 OPTIONX/ STACKX CF BOR1 BOR0 BORTRI M1 BORTRI M2 BP1 BP0 Bit 11 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. 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 foolows:
00b = 4.2V
01b = 2.6V
10b = 2.2V
11b = Brown-Out disabled BORTRIM1:
BORTRIM2 Brown-Out trim bits (parts are shipped out of factory untrimmed). BP1:BP0 Configure Memory Size:
00b = 1 page, 1 bank 01b = 1 page,    2 banks 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 Bit 0