PD1550A Parameter Fields

Many DUT test parameters can be obtained from the DUT data sheet.

Gate Resistance

Keysight Interface Test Modules have High- and Low-Side Gate Resistor (RG) Modules. The Control Software reads the value of the Gate resistors from the modules and displays the value. Both the Low-Side and High-Side RG,ON and RG,OFF resistances are shown.

Remember, both the High-Side and Low-Side Gate Resistor modules should have gate resistors of the same resistance value.

 

Click the refresh button next to the Gate Resistance to force the software to read the current gate resistor value. Do this when you first start the Control Software and anytime you change the Gate Resistor Modules.

DUT Parameters

  • Device Type (Drop-down menu item): Select either FET, IGBT, or GaN for the Device Under Test (DUT).

 

IMPORTANT: Testing GaN devices require a special DUT Test Interface Board and a license for the control software. Contact your local Keysight Application Engineer for availability and information.

  • Gate Threshold: Enter the Gate Threshold voltage from the device data sheet. If it is not available, enter “NaN” (not a Number).

  • Material (Drop-down menu item): Select either Si for Silicon or SiC for Silicon Carbide. This is generally available from the device data sheet. If unknown, select Not Specified.

  • Device Mode: (not available for IGBT device type) Select either Enhancement Mode (normally off device) or Depletion Mode (normally on device) for GaN or regular FETs. Refer to device data sheet. Default is Enhancement Mode.

  • MAX Voltage: Specify the maximum voltage (VDSS or VCES) that may be applied across the device (Drain to Source or Collector to Emitter). Obtain value from the device data sheet.

  • MAX Current: Specify the maximum current (ID or IC) that may be used to test the DUT (Drain to Source or Collector to Emitter). Obtain value from the device data sheet.

  • MAX Power: Specify the maximum power in Watts) that may be applied to the DUT. This value is sometimes not specified on the device data sheet.

As a general guideline, the typical operating voltage for a FET or IGBT is much lower than the Maximum Rated voltage (VDSS or VCES). The following examples are typical and not hard rules:

VDSS Rating:           Typical Operating Voltage:
          600 V                       400 V
       1200 V                       600 V
        1700 V                      900 V

 

  • Model ID: A text field to enter the model or device type of the DUT, or any other text information you want to record. Characters not legal for file paths (e.g., \, /, ?, <, >, ...) are replaced by the character “_”. If nothing is entered, the word “Unknown” is used.

  • Comments: Allows you to enter comments such as test details or DUT details. Comments are saved as part of the Measurement History and in the Parameters Results page.

GaN devices have different system limits than FET or IGBT devices. GaN devices are limited to:
     Maximum System Voltage ³ 500 V
     Minimum System Current: ³ 1 A
     Maximum System Current ³ 100 A

 

Standard or Reverse Tabs

  • Loop Count: Specify number of times to repeat the DPT test with the current parameter settings. See Note, “Looping or Sweeping Multiple DPT Tests” below.

  • Activate Low-Side Heater: Turns the heater circuit on or off. Remember to set the Temperature Control Settings in the Hardware Configuration > Fixture menu (see “Temperature Control Settings”).

    • Temperatures: Enter a single value or a semicolon (;) delimited list of temperatures to heat the device to when running the DPT tests. 175 °C Maximum. This box is grayed-out unless Activate Low Side Heater is checked. See Note, “Looping or Sweeping Multiple DPT Tests below.

 

The Low-Side and High-Side heaters are not used in the PD1550A. These settings have no effect on DPT measurements.

 

  • Loop delay: Specify the delay time (in seconds) for the DPT test to idle before running each DPT test in a loop. This time allows the device to cool if you use the heater. See Note, “Looping or Sweeping Multiple DPT Tests” below.

 

Looping or Sweeping Multiple DPT Tests. When running multiple tests on a device, loops are nested:

     Loop Count {
          Temperature {
               Multiple List or Sweep Voltage Values (VDS) {
                    Multiple List or Sweep Current Values (IDS)
                    }
               }
           }
That is, all “Current Values” are tested before incrementing the “Voltage Value”. All “Voltage Values” are tested before incrementing “Temperature”. All “Temperatures” are tested before incrementing “Loop Count”. When looping DPT tests, all measurement data is saved in the directory specified in the “Settings > Global Settings” menu.

 

  • Use Test Pulse (checkbox): When checked, click Start to run a low voltage/low current Double-Pulse Test (50 VDS) before the actual measurement begins. This verifies that the DUT is functional and has not been destroyed. Note, because of the low voltage/low current, the IG and IDS measurements will appear noisy on the oscilloscope. If the Test Pulse measurement succeeds, the complete test runs at full voltage and current. The Test Pulse is available only in Standard Test mode.

  • Extract Switching Characteristics: (checkbox) If not checked, only the Extract Gate Charge, Enable Screenshots, and Export Raw Data check boxes are available. When it is checked, an Extraction Standard drop-down menu, the Extract Switching Locus and Extract IV Curve check-boxes become available.

    • Extraction Standard: Select Legacy Mode, IEC 60747-8 for FETs, or IEC 60747-9 for IGBTs.

      • In Legacy mode, 0 V is defined as 0% for both enhancement mode and depletion mode FETs; The measured VDS is used as 100%.

      • In the IEC modes, 0 V is 0% for enhancement mode FETs but the negative VGS start voltage is used for depletion mode FETs; the set VDS value is used as 100%.

    • Extraction Levels: This allows you to specify exact voltage levels for data extraction.

      • Use Gate Pulse Low for 0% of Vgs: For Enhancement Mode (normally off devices), use either 0 V or the specified negative Gate Pulse low voltage is used. For Depletion Mode devices, the specified negative Gate Pulse Low voltage is always used.

  • Extract Switching Locus: This allows you to specify the percentage used for ID/IC Turn Off level. Switching locus represents the voltage and current combination (ID / VDS) along turn-on and turn-off. It is generally used to make sure the locus is within the Safe Operating Area (SOA) of a device. Switching locus does not follow a standard. It shows output current over output voltage during the switching periods. The switching locus can be generated for any power transistor and the algorithm is independent from semiconductor material or device topology.

    For turn-off:

         -- Starts when the output voltage starts changing

         -- Stops when output current stops changing

    For turn-on:

         -- Starts when the output current starts changing

         -- Stops when output voltage stops changing

    The switching locus for turn-on and turn-off starts and stops at 0, unless there are no measured values close to 0. In this case, warnings are written to the log file.

    For more information, see Parameter Extraction Techniques.

  • Extract Gate Charge: (available only in Standard DPT Test) Gate charge characteristics measure the input charge of gate-controlled power transistors. The algorithm is generally defined by JEDEC, there is also an IEC standard. Allows you to specify either the Legacy mode or the JESD 24-2 definitions for Gate Charge. Accurate Gate Charge measurements require a high gate resistor (RG) value; typically 100 W or greater. Refer to How Gate Charge is Calculated.

    • Legacy Mode: Refer to the PD1000A help file for details.

    • JESD 24-2: This characterization is used primarily for Enhancement Mode FETs but can also be used for IGBTs. Refer to the PD1000A help file for details.

– Extract IV Curve (checkbox, available only in Standard DPT Test): This checkbox is grayed-out (not available) unless the Extract Characteristics box is checked. If checked, the complete I/V derivation is extracted and saved. If a Gate Drive Module with a gate resistor (RG) 10 or greater was used in the DPT test, then the Gate Charge data is displayed. Note: 100 Gate Resistor (RG) or larger is recommended for IV derivation.

  • Control Voltage Resolution: This field is grayed-out (not available) unless the Extract IV Curve box is checked. Enter a single voltage value to be is used for the extraction of the IV curves.

  • Enable Auto Smoothing: Enable Control Voltage auto smoothing during IV Derivation Extraction.

  • Voltage Smoothing Number: Set the number of points used for Control Voltage smoothing signal during IV Derivation extraction.

  • Enable Screenshots: Allows user to enable/disable the system automatically taking oscilloscope screen captures during a DPT test. Screen captures are saved in the test subfolder.

    • When disabled (default setting), the only screen captures taken are the Summary.png and the PulseAdjustment.png.

    • Disabling shortens the Standard DPT test time.

    • Enabling screen captures allows for easier test debugging.

  • Export Raw Data: When checked, it enables the export of raw curve data from the oscilloscope. When unchecked, decreases the Double-Pulse Test time but the “Oscilloscope Capture” is not displayed or saved.

  • Extraction Settings: When selected, allows extraction of Reverse Recovery information.

    • Current Smoothing Number: (available only in Reverse DPT Test). The output current signal is smoothed before extraction. IRRM is extracted with this smoothed signal. For each other extraction (tRR, charge, energy, di/dt, ti) an additional user smoothing (default of 10 smoothing points) is applied.

    • Integration End Time Threshold: (available only in Reverse DPT Test) The software searches for first crossings of 0.0 A, and first crossing of 0.25 IRM after current peak, etc. Default is 0.25 (25%); range is 0% to 99%. If you select Enable Screenshots for the extraction, you can see the measured time of Irrm x 25% in the RevRec_trr.png and RevRec_trr_zoomed.png images.

    • Expected Irrm: (available only in Reverse DPT Test). Maximum Reverse Recovery Current of a fast or ultrafast diode; such as often used in switch-mode power supplies). Enter the maximum current the body diode is rated for.

  • Low-Side DUT °C: Indicates the temperature of the DUT if the Heater/Thermocouple assembly is connected to the Test Fixture. If the Heater/Thermocouple assembly is not connected to the test fixture or if Activate Heater is not selected, NaN (Not a Number) is shown.

  • High-Side DUT °C: Not used in this version of software. Reserved for future use.

  • Ambient °C: Indicates the ambient temperature inside the Safety Hood enclosure. Sources for the temperature readings are three internal fixture sensors.

    Click the Refresh button to read the current temperatures.

In PD1000A Control Software version 2023-324, the temperatures are not displayed.

Measurement Parameters for Standard and Reverse Tests

Control Signal (Gate Voltage (VGS,L or VGE,L)):

  • Gate Pulse High: A single voltage level for the turn-on Gate Pulse. For the Standard tests, this is for the Low-Side device (DUT). For the Reverse Recovery test, this is for the High-Side device. Minimum value for the Gate Pulse High = +13 V. Maximum value = +29 V. The difference between Gate Pulse High and Gate Pulse Low must be less than 30 V.

  • Gate Pulse Low: The voltage level of the Gate Pulse; used to ensure the DUT is fully turned off. Minimum value = -10 V. Maximum value = 0 V.

The maximum difference between Gate Pulse High and Gate Pulse Low must not exceed 30 V.

  • Unused Transistor Gate Voltage: This sets the Gate Voltage for the device not being tested. For the Standard tests, this is the High-Side device (DUT).

  • 2nd On Time: Enter the time, in microseconds, when the DUT is turned on a second time (and VDS is minimum). For example, 2 microseconds is expressed as “2E-6”. Minimum 200 nS, Maximum 10 S.

  • Off Time: Enter the time, in microseconds, between when the DUT is turned off (and VDS is maximum) and when the DUT is turned on a second time. For example, 2 microseconds is expressed as “2E-6”. Minimum 200 nS, Maximum 25 S.

 

Keep 2nd On Time and Off Time as short as possible. IGBT and some other slow devices may require longer times. The pulse width must be long enough that the transistor turns fully on (e.g., > 1 mS). However, the pulse width must not be too long, otherwise, the measurement will be influenced by self-heating of the transistor. 200 nS is the minimum time.

 

Output Voltage (VDS,L or VCE,L):

The Double-Pulse Test can either test at a single VDS,L/VCE ,L Output Voltage, a list of semicolon-separated Output Voltages, Output Voltages or sweep a series with multiple VDS,L/VCE,L Output Voltages.

  • Single/List or Sweep tabs:

    • If Single/List tab is selected, then run test with a single voltage or a semicolon (;) delimited list of voltages (e.g., 50; 100; 200; ...).

    • If Sweep is selected, then enter the starting voltage, the ending voltage, and the number of points (voltages) to test. See note below: Sweeping Voltage Example.

      • Output Voltage(s): Minimum Voltage = 300 V, Maximum Voltage = 13600 VDC. This is the minimum voltage; at this voltage the system can reach 1000 A.

      • # of Points: Sets the number of voltage steps between Start and Stop for sweeping.

 

Sweeping Voltage Example: As a sweep example, suppose you want to run tests at the following VDS,L/VCE,L voltages: 100, 150, 200, 250, 300, 350, 400 Volts.
     - Check the Sweep tab.
     - Set Start to: 100.
     - Set Stop to: 400,
     - Set the # of Points to: 7. This sets the Step Size to 50 V.
     - Then click Start to run the test.

 

Also, see the Looping or Sweeping Multiple DPT Tests note above.

Output Current (ID,L or IC,L):

The Double-Pulse Test can either test at a single IDS,L or ICE,L Output Current, a semi-colon-separated list of currents or sweep with multiple IDS,L or ICE,L Output Currents.

  • Single/List or Sweep tabs:

    • If Single/List tab is selected, then run test with a single current or a semicolon (;) delimited list of currents (e.g., 20; 35; 50; ...).

    • If Sweep is selected, then enter the starting current, the ending current, and the number of points (currents) to test. See note below: Sweeping Current Example.

      • Output Current(s): Minimum current = 50 A, Maximum current = 1000 A.

      • # of Points: Sets the number of current steps between Start and Stop for sweeping.

 

Sweeping Current Example: As a sweep example, suppose you want to run Double-Pulse Tests at the following IDS or ICE currents: 10, 15, 20, 25, 30, 35, 40 Amps.
     -  Check the Sweep Current box.
     - Set Single/Start current at 10.
     - Set the Stop current at 40,
     - Set the # of Points at 7. This sets the Step Current to 5.00 A.
     - Then click Start to run the test.

 

Also, see the Looping or Sweeping Multiple DPT Tests Note above.

  • Current Tolerance%: Specify a Tolerance value used is setting the pulse width to obtain current values. For example, if you specify a current of 100 A and a tolerance of 5% then the actual current used in the test will be between 95 and 105 A. Value must be greater than zero (0).

  • Inductor Selection: With software version 2023.324 (and later), inductance selection is moved under the Output Current heading. You have the option to have the PD1550A automatically select (Auto) the correct inductor for the voltage and current settings, manually select (Manual) the inductor from the three inductors in the PD1550A system (25 H, 100 H or 600 H), or use an external inductor (External) connected to the front panel terminals of the PD1550A-010 Test Fixture. If you are using an external inductor, enter the value of the inductor, in H, in the field next to the selection.

    • Lower current results in less accuracy.

    • First pulse only. Current after 2nd pulse must not exceed 1100 A.

    • If IDS > 1.2 X VDS then Inductor selected = 25 H. If IDS < 0.1267 X VDS then Inductor selected = 600 H. Otherwise, Inductor selected = 100 H.

Run the Characterization Test

After selecting the type of test (Standard or Reverse Recovery) and setting the test parameters:

  1. Click the Start button () to start a measurement or a loop of measurements.

  • Stop an active measurement by clicking the Stop () button.

  1. The DPT Control Software calculates the amount of energy that it needs to store in the inductor for the complete test and sets the width of the first pulse accordingly.

  2. Watch the Progress details just above the button.

  3. After the test runs, and if Enable Screenshots is checked, the Oscilloscope Capture plot and other test data appear in the software display (right side of the display) on the host PC.

 

Test result data is automatically stored in the file specified in the Global Settings > Output Directory (see “Settings > Global Settings”).

 

If a Gate Drive Module with a gate resistor (RG) equal to or greater than 10 W was used in the DPT test, then the Gate Charge data is calculated and available. If RG is 0 Ohms. then the gate current cannot be measured.

 

Waveforms from the PD1550A Double-Pulse Tests system are different from waveforms shown in various test standards. This is because of issues such as gate plateau, ringing due to parasitic inductances and capacitances, voltage drop due to stray inductances, overshoot, etc

 

After a successfully completed test (or loop or sweep of tests). The right side of the screen displays the test results. The Results Tab shows the results of the most recent DPT test or the results of a test selected from the Measurement History.

 

See Also:

Measurement Results Screens