[time-nuts] Silicon Labs series of oscillators...

Michael Baker mpb45 at clanbaker.org
Sat Jan 22 09:04:21 EST 2011


   Hello, TimeNutters-
   Silicon Labs
   [1]http://www.silabs.com/products/clocksoscillators/pages/default.aspx
   offers a large assortment of various types of oscillator
   chips: XO, VCXO, programmable XO, clock generators,
   clock distribution chips, Jitter Attenuators, Clock cleaners,
   etc, etc....
   I have a need for a 110 MHz VCXO in a 1.8GHz to 7.5GHz
   tracking generator I am building for my Tek 494 spectrum
   analyzer.  I bought a pair of Silicon Labs 110 MHz VCXO
   chips for less than $25 for the pair from Cramer
   Distributors. The Si595 VCXO chips are in an
   "industry standard" 5mm X 7mm surface-mount package.
   Yikes!  I knew I was going to have trouble (for lack
   of thru-hole leads) breadboarding this chip.  However,
   I managed (using a magnifier-loupe and a v-e-r-r-r-y
   tiny soldering iron tip) to get some "legs" soldered
   onto the surface-mount pads. Great...  I inserted the
   critter into the socket-strips of my breadboard, hooked
   up the required 3.3vdc Vdd and ground and checked to
   see what it's output looks like.
   No joy.  Drat.  It has a set of complementary output
   pins. One sits at around 50% of Vdd and the other is low.
   When I pull the Output Enable pin high, the 50% output
   pin goes low.  The other (complementary) pin just stays
   low.  If I pull the Output Enable pin low, neither
   output pin changes.
   Drat.  I must have destroyed the little critter during
   the leg soldering process.  These chips are supposed
   to be pretty static from normal handling and-- here in
   humid Flori-DUH, handling problems from static build-up
   is almost a non-existent problem.  Even so, I do all my
   breadboarding on a 3-foot X 2-foot static-drain pad.
   Sooooo.... I used the utmost care in soldering legs to
   the second chip.  The surface-mount pads are gold-plated
   and it is super easy to just momentarily tap them with the
   soldering iron tip and leave a very teensy blob of
   solder on each one.  Using pre-tinned gold-plated
   legs stripped from some surplus 1/8 Watt resistors, I
   fastened the legs on the chip with only the briefest
   time of soldering-iron tip contact; less than one second,
   I am guessing.
   Same result with the second chip; the outputs appear to
   be dead.
   I guess this sad saga boils down to my question for the
   Time-Nutters List: How do you deal with breadboarding
   when it comes to parts that are ONLY available in
   surface-mount configuration (and are just at the size
   limit for hand soldering?
   Thanks for any input on this!
   Mike Baker
   Micanopy, FL
   ------------------------

References

   1. http://www.silabs.com/products/clocksoscillators/pages/default.aspx



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