Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
test-and-measurement:analog-discovery-pro-5250:transistor-tester [2022/01/13 09:32] – [Writing the Script] Álmos Veres-Vitályostest-and-measurement:analog-discovery-pro-5250:transistor-tester [2022/10/04 11:38] (current) – external edit 127.0.0.1
Line 15: Line 15:
   * [[test-and-measurement:analog-discovery-pro-5250:start|]]   * [[test-and-measurement:analog-discovery-pro-5250:start|]]
   * [[https://www.diodes.com/assets/Datasheets/ZVN3310A.pdf|ZVN3310A]], or other transistor   * [[https://www.diodes.com/assets/Datasheets/ZVN3310A.pdf|ZVN3310A]], or other transistor
-  * 2x 10W 100Ω ceramic resistors+  * 2x 10W 51Ω ceramic resistors
  
 === Software === === Software ===
Line 29: Line 29:
 In this test, the drain current versus the drain-source voltage of the selected MOSFET will be plotted for varying gate-source voltages. Connect the gate of the transistor to the waveform generator and the source to the ground. In this test, the drain current versus the drain-source voltage of the selected MOSFET will be plotted for varying gate-source voltages. Connect the gate of the transistor to the waveform generator and the source to the ground.
  
-To limit the maximum drain current, a 50Ω resistor is needed in series with the transistor. The maximum output current of the ADP5250 on the +25V supply is 500mA, so the maximum power dissipated by the resistor, in the case of an ideal switch instead of the MOSFET (with 0Ω resistance), would be $P_{R}={I_{R}}^{2}*R={(0.5A)}^{2}*50Ω=(0.25*50)W=12.5W$ which is higher then the rated power of the 10W ceramic resistors so two pieces of 100Ω resistors will be used in parallel (the current is divided equally between them, so the dissipated power will be only half, which is 6.25W, below 10W).+To limit the maximum drain current to the maximum output current of the supplies, a $R=\frac{V}{I}=\frac{V_{+}-V_{-}}{I}=\frac{25V+25V}{0.5A}=100Ω$ resistor is needed in series with the transistor. 
 + 
 +The maximum output current of the ADP5250 on the +25V and -25V supplies is 500mA, so the maximum power dissipated by the resistor, in the case of an ideal switch instead of the MOSFET (with 0Ω resistance), would be $P_{R}=I_{Rmax}*V_{Rmax}=0.5A*50V=25W$ which is higher then the rated power of the 10W ceramic resistors. To protect the circuit, two pieces of 51Ω resistors will be used in series, so the voltage is divided equally between them, the dissipated power being only half, which is 12.5W. This is still above 10W so the maximum voltage should also be reduced. If the maximum voltage drop is only 40V, the dissipated power by the resistors will be $P_{51R}=\frac{I_{Rmax}*V_{Rmax}}{2}=\frac{0.5*40V}{2}=10W$
 </WRAP><WRAP half column> </WRAP><WRAP half column>
-{{ :test-and-measurement:analog-discovery-pro-5250:transistor_tester_sc.png?600 |}}+{{ :test-and-measurement:analog-discovery-pro-5250:transistor_tester_sch.png?600 |}}
 </WRAP></WRAP> </WRAP></WRAP>
  
Line 41: Line 43:
 </WRAP> </WRAP>
 </WRAP><WRAP half column> </WRAP><WRAP half column>
-{{ :test-and-measurement:analog-discovery-pro-5250:transistor_tester_bb.png?600 |}}+{{ :test-and-measurement:analog-discovery-pro-5250:transistor_tester_bbd.png?600 |}}
 </WRAP></WRAP> </WRAP></WRAP>
 ---- ----
Line 47: Line 49:
 ===== Writing the Script ===== ===== Writing the Script =====
 <WRAP group> <WRAP group>
-The full script can be downloaded {{|here}}.+The full script can be downloaded {{ :test-and-measurement:analog-discovery-pro-5250:transistor.zip |here}}.
 </WRAP> </WRAP>
  
Line 61: Line 63:
 # parameters # parameters
 Vd_resolution = 500 # drain voltage resolution in mV Vd_resolution = 500 # drain voltage resolution in mV
-Vd_limit = 25       # maximum drain voltage in V+Vd_limit = 40       # maximum drain voltage in V
 Vg_resolution = 2   # gate voltage resolution in V Vg_resolution = 2   # gate voltage resolution in V
 Vg_limit = 12       # maximum gate voltage in V Vg_limit = 12       # maximum gate voltage in V
Line 109: Line 111:
             print("\tDrain voltage: " + str(drain_voltage) + "V")             print("\tDrain voltage: " + str(drain_voltage) + "V")
             # set the drain voltage             # set the drain voltage
-            supplies.switch_25V(device_handle, True, False, drain_voltage, 0)+            if drain_voltage > 25: 
 +                supplies.switch_25V(device_handle, True, True, drain_voltage - 25, -25) 
 +            else: 
 +                supplies.switch_25V(device_handle, True, True, 0, drain_voltage * (-1))
  
             # delay             # delay
Line 162: Line 167:
 ===== Testing ===== ===== Testing =====
 <WRAP group><WRAP half column> <WRAP group><WRAP half column>
 +Turn on the ADP5250 and start the script. Wait for it to finish. You can save the plotted results by clicking on the respective button. Compare your results to the one presented in the datasheet of the transistor.
  
-</WRAP><WRAP half column>+<WRAP center round important 80%> 
 +The resistors and the MOSFET might get hot! Don't let the setup unsupervised!!! 
 +</WRAP>
  
 +</WRAP><WRAP half column>
 +{{ :test-and-measurement:analog-discovery-pro-5250:output_zvn3310a.png?600 |}}
 </WRAP></WRAP> </WRAP></WRAP>
 ---- ----