.DF

  To: John Wheeler                                      Date: July 13, 1984

From: Rob Horning                                    Subject: +3 V Supply

  cc: Craig Robinson
.DE

This is a summary of the risks and cost involved with setting the tolerance
on the +3 supply for the Firefox MC at 5% as opposed to 10%.  If 5% tolerance
is needed then a voltage regulator will be required.

.DL
.LI
Board Space - The Firefox memory board is very crowded and adding the voltage
regulator would use a significant amount of the spare area.  The less spare
space that we have the more likely it is that some small problem in the future
will become a a big problem. (Causing the board to be completely relaid out
late in the program)
.LI
Cost - The cost will be effected in two ways.  First there is the cost of the
regulator. Second there is the cost of hand loading and soldering it because
we may not be able to find an acceptable surface mount regulator.
.LI
Resource - It will take a couple of weeks of my time to select and test
voltage regulators in an effort to make it surface mountable.  There is
a good chance that this effort will fail.  If it does not fail if will
take more time.
.LI
Reliability - The voltage regulator will increase the failure rate of the
board.
.LE

I have not spent a lot of time quantifying the cost and risk of having
the regulator and I hope I do not have to.  It appears to me that it would be easier, cost less,
and be less risk to make the tolerance 10%. (7% would be ok for the memory
board, but maybe not the CA chip.)

I need to get this issue settled in the next week or two (before I go into
PC lay out).

