CURRENT REGULATOR DIODES

781-J500-E3, 781-J501-E3, 781-J502-E3, 781-J503-E3, 781-J504-E3,
781-J505-E3, 781-J506-E3, 781-J507-E3, 781-J508-E3, 781-J510-E3,
781-J511-E3, 781-SST502-E3,781-SST502-T1-E3,781-SST503-E3,
781-SST503-T1-E3, 781-SST504-E3, 781-SST504-T1-E3,
781-SST505-E3, 781-SST505-T1-E3, 781-SST506-E3,
781-SST506-T1-E3, 781-SST507-E3, 781-SST507-T1-E3,
781-SST508-E3, 781-SST508-T1-E3, 781-SST509-E3,
781-SST509-T1-E3, 781-SST510-E3, 781-SST510-T1-E3,
and 781-SST511-T1-E3

In late 1999, Siliconix closed the wafer fabrication plant in
Santa Clara, which had been their source for JFET wafers for
many years.  They then contracted with a foundry for continued
supply.  In 2005, their foundry source announced the closure of
the line supporting JFET demand, and they placed and completed a
lifetime buy for these devices.

They are currently in the process of finding a new source, and
expect that to be completed and on line in the second half of
2007. In the meantime, Vishay-Siliconix can support JFET demand
only from their existing inventory of wafers. They cannot add to
that inventory.

Typically, a given JFET die type yields to a number of JFET
part-types. Depending on the parts needed, the wafer lot must be
targeted so that the yield is optimized to support the
parameters needed. If wafers in stock are not targeted
correctly, yield for a given part may be very low, meaning you
can have the right die type, but not be able to yield to the
specific part.

Since they cannot target new wafer lots to support specific
parts, they are now finding that they cannot yield any good
parts to specific parts in the JFET product line. And
specifically for the J5xx and SST5xx N Channel Current
Regulators, they find that they cannot reliably yield parts
given their existing wafer inventory.

For this reason, they have put this series on order hold,
preventing any new orders from booking.  This hold will stay in
place until they have qualified a new source for wafers, and can
begin targeting to yield specific parts in the range, as they
have in the past.

If a particular new customer need is urgent, they can evaluate
their existing inventory and see if they can support it. In
general, they will not be able to do so. They recommend that for
the time being, customers seek alternate sourcing for this
series.



5-1206-28