At 07:17 AM 5/13/2005 -0400, you wrote:

>Of course none of this should be a rule.  There are always unique tradeoffs
>for every product.  A good case for a wall wart with a switcher is when you
>need enough power so that a transformer directly from the AC line would be
>too large, or universal input power is important.

If the product is going to be shipped long distances by air, the weight
saving from using a SMPS adapter should be taken into account. The cost
savings can be in the dollars per kg range. Even if that's not important,
the packing and overall size (cost of sea shipments of electronic goods are
usually determined by the volume, not weight) can be much less if there isn't
a heavy battering ram packed in each box.

Presumably the combination of factors (including international approvals
and universal input) led Microchip to standardize on a 9VDC-out switching
adapter with separate cord and secondary regulation on the products.

I was a bit surprised that Nintendo supplies only a 120V SMPS adapter to
recharge their Gameboy Advance SP. I guess they thought the few pennies
they saved by optimizing the SMPS for a single input voltage was worth
it (it's quite small, and the US/Canada version has a folding AC plug).
I picked up a replacement universal supply for the kid's Gameboy
at the Blockbuster for US8.00 retail. (marked "100-240VAC
5V/1.2A set at 0.32A", whatever that means**!). If you need a tiny wall-plug
5V supply in a hurry at 10pm, there's a possibility (we were heading off
to China*** the next morning and the Gameboy is a vital accessory..
a bit like a sedative). It has a strange rectangular connector, a bit
like USB and Firewire connectors, not sure if mating connectors are
easily available (but it could be cut off).

5.36V no load
5.26V at 100mA

** the original adapter has a 320mA rating, so perhaps the 3rd party
adapter is approved for 1.2A but they've set the current limit at
320mA for this application to match the original.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
 >>>Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff




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