... | ... | @@ -16,20 +16,21 @@ ceilings on frequency repetition and fixed pulse width values. |
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## Aim of stress tests
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Two modes of operation are foreseen for the new version of the
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CONV-TTL-BLO board. The aim of these tests will be slightly different
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depending on the mode of operation:
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- **Continuous mode**: Pulses in this mode are a standard 1.2us long
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and can be repeated continuously, provided their rate at the input
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is below the stated maximum frequency for the continuous mode. For
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higher input rates, pulses will be missed on the output and a flag
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will be raised.
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CONV-TTL-BLO board. It will in fact be able to operate short 250ns
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pulses and long ones at 1.2us. The aim of these tests will be to
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identify the operating frequencies in these two modes, in the following
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scenarios:
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- **Continuous**: Pulses can be repeated continuously. For higher
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input rates, pulses will be missed on the output and a flag will be
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raised.
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\> Aim of tests: Identify maximum pulse frequency supported by the
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blocking output stage for continuous operation.
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- **Fast mode**: The CONV-TTL-BLO board will use shorter, 250ns pulses
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to support higher frequencies (greater than that of continuous
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mode), provided it is for a limited amount of time. This mode of
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operation is also known as burst mode.
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blocking output stage for continuous operation for both pulse
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lengths.
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- **Fast**: The CONV-TTL-BLO board will can support higher frequencies
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(greater than that of continuous mode), provided it is for a limited
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amount of time. This mode of operation is also known as burst
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mode.
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\> Aim of tests: Identify the maximum repetition frequency that can
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be achieved and how long before this frequency can cause
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irreversible damage to the board.
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... | ... | @@ -44,11 +45,13 @@ The outcome of these tests can take a number of forms: |
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## Minimal pulse definition:
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- **Pulse width**: It shall be specified as 1.2us in the continuous
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mode and 250ns for the fast mode. The short 250ns pulse is long
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enough to match exisisting CERN pulse repeaters (Fast versions), and
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short enough to cause as little temperature rise in the power MOSFET
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as manageable.
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- **Pulse width**: It shall be specified as 1.2us for the long pulse
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definition and 250ns for the short pulse definition. The short 250ns
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pulse is long enough to match exisisting CERN pulse repeaters (Fast
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versions), and short enough to cause as little temperature rise in
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the power MOSFET as manageable. The short pulse mode should
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therefore achieve the highest frequency rates, foreseen at around
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2MHz.
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- **Maximum allowable frequency**: This is equivalent to the maximum
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duty cycle allowed for 250ns pulses. An initial maximum 12.5% duty
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cycle will be assumed. This corresponds to maximum 500kHz pulses.
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... | ... | @@ -67,9 +70,10 @@ control and output data. |
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### Hardware
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- CONV-TTL-BLO V3 and RTM (Rear Transition Module) board plugged on
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VME64x ELMA crate and reachable via telnet.
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- CONV-TTL-BLO V3 (Note 1) and RTM (Rear Transition Module) board
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plugged on VME64x ELMA crate and reachable via telnet.
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- Oscilloscope to check for pulse shape one channel at a time.
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- Temperature probe To check MOSFET temperature.
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- Computer on same network as ELMA crate and running the necessary
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software (Python) scripts.
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- Lemo cables and appropriate termination to be used to connect the
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... | ... | @@ -103,9 +107,11 @@ control and output data. |
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performance. Two channels will be used, as shown in Figure 1, above:
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- **A Channel under tests (CUD)**: This channel output circuit
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will be tested for performance with incrementally increasing
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repetition frequency, until it is irreversibly damaged. The
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point at which this occurs needs to be recorded and used as a
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**time to failure** figure. If the same test is repeated on
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repetition frequency, until it is irreversibly damaged. Since
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irreversible damage is an extreme point to reach, the tests are
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stopped when temperature reaches a high value of 70Deg (Note 2).
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The point at which this occurs needs to be recorded and used as
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a **time to failure** figure. If the same test is repeated on
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multiple channels than a **mean time to failure** figure may
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also be calculated.
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- **A monitoring channel (MC)**: This can be any one of the other
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... | ... | @@ -117,12 +123,13 @@ control and output data. |
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<!-- end list -->
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- In software:
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- Set pulse width to 250ns.
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- Set pulse width.
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- Each test will run a chosen repetition frequency, from list, Eg:
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1kHz, 5kHz, 10kHz, 50kHz, 100kHz, 150kHz, 200kHz, 300kHz,
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400kHz, 500kHz.
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- The test must be stopped when the blocking output fails. This is
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detected when:
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- The test must be stopped when the blocking output is considered
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"too hot". This is detected when:
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- The temperature probe indicates 70deg or higher.
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- The blocking output pulse disappears from the Oscilloscope
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screen (Or when the damage to blocking output is seen... or
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smelt). The test must be stopped.
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... | ... | @@ -134,12 +141,19 @@ control and output data. |
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- The outcome of tests will be recorded on a log sheet, that can
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be found in the files section below.
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### Test results:
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Tests have been carried out and the results are shown in the following
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two diagrams for long and short pulses:
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-----
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Note 1: As a minor bug has been identified in V3 boards, which has been
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described in issue \#1404. The V3 prototypes used in these stress tests
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will have the missing resistor manually added, before being permanently
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added in V4 boards.
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added in V4 boards.
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Note 2: Tests are run in worst case conditions, with a crate that is not
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ventilated.
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