T h e   M u l t i p l e x e r s

 

 

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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.

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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.

mult1.jpg (112250 bytes)

A typical example is the MUX 16.300

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 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.

 

 

 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.