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An Introduction
The term “multiplexer” is used by Challenge Innovations to denote a multiple
way “switch” which routes a DUT (Device Under Test) connector on the front
of an ATS-2 or similar Static Parameter Tester to a number of DUTs. These
can be individual devices or multiple devices inside a module.
A typical example is
shown below. This routes the DUT socket on an ATS-2 Static Tester to 16 DUT outlets mounted on the multiplexer’s
(MUX.16.100)
front panel.
Each “switch” consists of 6 poles,
two for Collector/Drain, two
for the gate and two for the emitter/source leads on the DUT. Four of these switches use reed
relays capable of 2kV and 1A max.
for the sense and gates.
The other two are power switches and are made to suit the maximum
current that will be carried and how that current is distributed from the
Tester. Relay contacts are used with capabilities of 16A DC to 30A DC
depending on the application. Lifetimes of > 50 million operations can
be expected from each contact as all are switched
with no current flowing. The reed relys have a much longer
lifetime.
The 16A relays are used to carry up to 100A
max. for 400usec. generated by
the 100A version of the ATS-2. Three are used to carry the separate 100A
max. currents generated by the 300A version of the ATS-2.
The 30A DC relays are used to
carry the DC generated by the PDA-4
and TRA-2 Tjc Testers and the SBA-3
FBSOA Testers.
Control of all relays is via the Testers
MUX output socket and the operating software. It is completely transparent
to the user.
The
16 groups of relays in the MUX.16.100 example above are switched together.
Another design
is the “Scanner” where each relay
contact is activated separately under software control. The above example
would be a 6 input - 96 output scanner.
Challenge Innovations make both types of
design but recommend the “multiplexer” type. The scanner would save some
external wiring to the DUT but the software definitions and the relay
driving requirements are far more complex and prone to errors.
All
the multiplexers include internal power supplies,
decoding circuitry and, when
Igbt or Power-fets are to be tested, the gate resistors with their own relays. Normally all the
gates are kept referenced to their emitters via 200R resistors until a test
is applied which requires an open gate-emitter.
The Standart
"Relay Type" Multiplexers include:
Type No. of outlets
Capability Tester
MUX.30.100
30
2kV / 100A
ATS-2 / 100A
MUX.16.100
16
2kV / 100A
ATS-2 / 100A
MUX.16.300
16
2kV/
300A
ATS-2 / 300A (Picture shown below)
MUX..8.300
8
2kV/
300A
ATS-2 / 300A
MUX.8.600
8
2kV /
600A
ATS-2 / 300A + 300A Booster
MUX.4.1200
4
2kV/ 1200A ATS-2
/ 300A + 900A Booster
MUX.2.2400
2
2kV /
2400A
ATS-2 / 30A + 1200A Booster
+900A Booster
Special "Relay
Type" Multiplexers give the choice of:
- DUT Outlet connector type,
- Number of DUT outlets and their position,
- Parallel multiplexer relays for Tjc/FBSOA test types
Please contact Challenge Innovations or their Agents for prices and details of
the best multiplexer design for an application.
A typical example is the MUX 16.300
In general;
-
The front panel shows the status of the two internal power supplies.
-
The front panel includes the drive link to the Safety Test Head.
- The
rear panel carries the IEC type mains input socket, the link to the DUT outlet and the link to the
MUX control socket both on the front panel of any ATS-2 Static Parameter Tester.
- All
the multiplexer cards have a card mounted led to show the active
position and a push-button to bring on that
multiplexer position for testing.
- There is a
manual test box provided which activates the required position for test purposes.
There is also a simple QBASIC programme provided which brings on one
position at a time.
The DUT outlets can be used as required. For example, multiple devices
inside a module can be wired to th separate MUX outlets, a group of
individual devices can be tested in sequence etc.
If hand insertion of
the DUT devices is necessary, then a Safety Test Head needs to be used.
This can be mounted on the front of the Multiplexer box to form one unit or
kept as a separate unit. with plugs to the DUT outlets.
All the Challenge Innovations Safety Test Heads can be considered
depending on the size and shape of the DUT. Please refer to the appropriate "Information"
sheet for details.
Please Note.-For Dynamic Parameter testing,
special multiplexers are designed and made part of the Dynamic Test Head.
This MUX x y standard range is not suitable for high speed switching.
Please refer to the STA-3 Dynamic Parameter Tester"Introduction"
data for further information.
The “Pneumatic” High Current Multiplexers;
The concept of keeping all the currents down to a max. of 100A pulsed
per switch for the ATS-2 and 30A DC per switch for the Energy Dissipation testers gives at least
two advantages;
1.
it keeps the inductance problems, associated with trying to switch high
currents on
and off at relatively
high speeds, low and
2.
allows the use of readily available relays rather than special high cuurent
types
The problem is that many such switches are needed as the
current requirement increases..
As an example, a 1500A ATS-2 will have 15 x 100A max.
generators It will need 15 power
relay contacts for the collector power and 15 for the emitter power
for each of the multiplexer outputs. If a quad DUT is to be tested, then
the total number of power relays reaches 120, presenting a problem in
housing them and keeping the wiring lengths short. The MUX.2.2400, the
MUX.4.1200, the MUX 8.600 and the MUX 16.300 all need 96 relays and this is
a practical limit to the "Relay Type" design.
Challenge Innovations use a pneumatically
activated multiple -
Bed-of-Nails design to overcome such problems.
Each multiplexer position is a separate Bed-of-Nails with
multiple high current probes each carrying the separated max. currents.
This gives great flexibility and a better switches-per-volume than the
relays.
Another grat advantage is that the separation of the
switches when open can be made very large giving a high voltage isolation
when off. The voltage available to the DUT can then be made very high.
Normally this is up to 10kV but the design can be used for much greater
values.
The following “Pneumatic” High
Current multiplexers are available;
- 2 or 4 positions each capable of 1500A / 2kV
pulsed,
- 2 or 4 positions each capable of 1500A plus each position capable of
>2kV up to 10kV using the external EHT power supply option on the
ATS-2
Tester.
(1500A = one 1200A Booster plus a 300A ATS-2)
- 2 or 4 positions each capable of 2700A / 2kV
pulsed,
-
2 or 4 positions each capable of 2700A plus each position capable of
>2kV up to 10kV using the external EHT power supply option on the
ATS-2 Tester.
(2700A = two 1200A Booster plus a 300A ATS-2)
- 12 positions each capable of
1200A/2kV pulsed (coming from a 300A ATS-2 Tester
and it’s 900A
booster plus 360 Amps DC
coming from a PDA-4 Tjc Tester).
The housings of the above can be
integrated into the required
Safety Test Head box to keep the wiring as short as possible or kept as
separate items.
A
typical example is an integrated Safety TEst Head Type MCP-3HV together
with a 2 x 1500A positicon pneumatic multiplexer, one relay multiplexer
position and an 8kV/75mA high voltage programmable power supply. All are
fitted on to a floor standing trolley and all are controlled by an ATS-2
Static Parameter Tester. This example is used to test the 6.5kV range of
Igbt modules used in power traction power supplies together with the 3.3kV
and lower ranges of Igbt modules.
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The
insert shows a 6.5kV Igbt Module loaded onto the open trolley of the
MCP-3HV Safety Test Head.
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Special Designs;
Challenge Innovations has a long and broad experience in the
design and construction of “special” multiplexers and scanners. If the
range outlined above is not suitable, then a special design or variation of
an existing design will can be made.
Please use the “Information
Exchange” page on this web site to tell us of your requirements.
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