Kantronics KPC-3 Plus - Appendix C: Options for the KPC-3 Plus; Low Power Operation; Expanding the RAM in the KPC-3 Plus; Installing the Optional Real-Time Clock Module

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Appendix C: Options for the KPC-3 Plus
Low Power Operation
Your KPC-3 Plus is capable of very low power operation. In order to achieve the lowest
power consumption possible, you must turn the front panel LEDs off with the command
LEDS OFF. Also, the modem must be set for INTERNAL carrier detection with the
command CD INTERNAL. In this configuration, the KPC-3 Plus will draw less than 15
mA when no signal is being received. Note, however, that the actual current drain may
vary slightly depending on the RS232 connections to the unit. Some computers will
cause the current drain to be slightly higher than other computers.
If you use software carrier detection (CD SOFTWARE) the current drain will be higher in
the ―idle‖ mode since the processor is actively looking for data even when no signal is
present.
Very Low Power Operation
KPC-3 Plus circuitry is powered from a linear low dropout regulator at 5.0 V nominal. At
this voltage, current requirements vary from approximately 16 mA (unit idle and LEDs
OFF) to 23 mA (unit transmitting and LEDs ON). By placing a jumper on J16, the output
of the voltage regulator is reduced from 5.0 V to 3.3 V nominal, thus reducing power
requirements nearly in half. The current requirements in this case vary from
approximately 8.5 mA (unit idle and LEDs OFF) to 12 mA (unit transmitting and LEDs
ON).
The 3.3 V mode of operation has not been thoroughly tested in the field and is not
guaranteed. The unit may not function properly over extreme temperature ranges when
operating at 3.3 V.
Expanding the RAM in the KPC-3 Plus
The KPC-3 Plus is supplied with 128 KiB of RAM. It is possible to expand the RAM in
the KPC-3 Plus from 128 KiB to 512 KiB.
Expanding the RAM to 512 KiB requires that you: (1) remove the existing 128 KiB RAM
in socket XU14, (2) change jumper J14 to the center pin and pin 2 (to left of the RAM
chip), then (3) install a 512 KiB low-power static RAM in XU14, with the pin 1 end of the
IC toward J14.
NOTE: in the latest circuit board revision, components are SMT type, and the maximum
size 512K static RAM is standard.
Installing the Optional Real-time Clock Module
The Real-time clock option for the KPC-3 Plus consists of a FOX 72421 self-contained
clock chip.