' 1999 Scenix Semiconductor, Inc. All rights reserved. 1 www.scenix.com Summary of Changes SX18/20/28AC Devices with
Datecode yywwxx (old rev) SX18/20/28AC devices with
Datecode Axyywwxx (new rev) FUSE Word Register DIV2:DIV0 - Internal RC Oscillator
Divider: Bits DIV0, DIV1, and
DIV2 are located in bit locations 4,
5, and 6 respectively and provides a
selection of 8 frequencies OPTIONX - OPTION Register
Extension: Ability to disable pro-
grammability of bits 6 and 7 (RTW,
RTE_IE bits). STACKX - Stack Extension: Limits
the stack size to two levels or
extends the size to 8 levels. DIV1:DIV0 - Internal RC Oscillator
Divider: Bits DIV0, and DIV1 are
located in bit locations 5, and 6 respec-
tively and provides a selection of 4 fre-
quencies. Bit 4 is reserved.Bit DIV0 and
DIV1 also dual functions. DIV0
(FOSC2) extends the external oscillator
configuration. DIV1 (IFBD) is the inter-
nal feedback resistor disable bit for the
external resonator/crystal oscillator. Moved  to  bit  7  of  the  FUSEX  register.
The bit position is reserved. Moved  to  bit  7  of  the  FUSEX  register.
The bit position is reserved. FUSEX Word Register MEM1:MEM0 - Configure Program
Memory Size: Configures the pro-
gram memory size if desired to be
different than the factory setting. RAM1:RAM0 - Configure Number
of RAM Banks: Configures the
number of RAM banks if desired to
be different than the factory setting. BOR1:BOR0 - Brown-Out Reset:
Can disable the Brown-Out feature
or enable and set the trip point to
4.2V. BP1:BP0 - These bits configure both the
program memory size and the number
of RAM banks. See the register map for
details. The bit locations are used for trimming
the Brown-Out trip point (factory
untrimmed). The number of RAM
banks is selected through the BP1 and
BP0 bits. BOR1:BOR0 - Brown-Out Reset: Can
disable Brown -Out feature or enable
and select 3 different trip points. External Crystal/Resonator (LP,
XT, or HS Mode) The FOSC1:FOSC0 bits provide 3
settings. The FOSC2:FOSC0 bits provide 7 set-
tings. External Crystal/Resonator Oscil-
lator Component Values Specified in the datasheet (latest
version is dated 2/11/99) The component values (Rf, C1, C2) val-
ues are different. Target values are
available for reference. Supply Voltage 4.5V to 6.25V 2.5V to 5.5V Parallel/Serial Prog. Times 100 ms/word < 50 ms/word Tools Support SX Key Rev E, Soft Rev 1.05 SX Key Rev E, Soft Rev 1.06