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Peak Atlas DCA Pro

 User Guide

June 2019 

–

 Rev 1.7

Page 23

 Depletion Mode MOSFETs

The  fairly  rare  Depletion  Mode  MOSFET  is  very similar  to
the conventional  Junction  FET  (JFET)  except  that  the  gate
terminal is insulated from the other two terminals. The input
resistance of these devices can typically be greater than 1000M

Ω

 for negative

and positive gate-source voltages.

Depletion 

Mode 

devices 

are

characterised by the gate-source voltage
required  to  control  the  drain-source
current.

Modern  Depletion  Mode  devices  are
generally  only  available  in  N-Channel
varieties and will conduct some current
between  its  drain  and  source  terminals
even with a zero voltage applied across
the gate and the source. The device can
only be turned completely off by taking
its gate significantly more negative than
its  source  terminal,  say 

–

5V.  It  is  this

characteristic that makes them so similar
to conventional JFETs.

Содержание Atlas DCA75 Pro

Страница 1: ... with Graphics Display and PC connectivity Model DCA75 Designed and manufactured with pride in the UK User Guide Peak Electronic Design Limited 2012 2019 In the interests of development information in this guide is subject to change without notice E OE GB75 1 7 ...

Страница 2: ... Contents Page Introduction 4 Important Considerations 5 Analysing Semiconductors Standalone mode 6 Diodes 8 Zener Diodes 9 Diode Networks 10 LEDs 11 Bicolour LEDs 2 lead types 12 Bicolour LEDs 3 lead types 13 Bipolar Junction Transistors BJTs 14 Darlington Transistors 18 Digital Transistors 21 Enhancement Mode MOSFETs 22 Depletion Mode MOSFETs 23 Enhancement Mode IGBTs 24 Depletion Mode IGBTs 25 ...

Страница 3: ...acing functions 35 PC mode Exporting your data 36 PC mode Special functions 37 Audible Settings 38 Care of your Peak Atlas DCA Pro 39 Appendix A Troubleshooting 40 Appendix B General Technical Specifications 41 Appendix C Component Testing Specifications 42 Appendix D Analysis test circuits 44 Transistor test circuit 44 JFET MOSFET IGBT test circuit 45 Diode test circuit 46 Voltage regulator test ...

Страница 4: ...g Bicolour LEDs 2 and 3 leads Diodes and Diode networks Zener diodes 11V Voltage regulators 8V Automatic pinout identification just connect any way round Special feature identification such as free wheeling diodes and resistor shunts Gain measurement for bipolar transistors Leakage current measurement for bipolar transistors Silicon and Germanium detection for bipolar transistors Gate threshold an...

Страница 5: ...e to your DCA Pro and invalidation of the manufacturer s warranty The DCA Pro is designed to analyse semiconductors that are not in circuit otherwise complex circuit effects will result in erroneous measurements Large voltage differences between true earth and your PC s USB port can result in damage The device under test should therefore have no path to earth or other supplies Avoid rough treatmen...

Страница 6: ...ton is pressed For the first analysis the tests are performed while displaying the Peak logo no time is wasted while displaying the logo For subsequent testing when the unit is already powered up the unit displays the Testing screen Depending on the component type analysis may take a few seconds to complete after which the results of the analysis are displayed Information is displayed a page at a ...

Страница 7: ... being displayed Some components may be faulty due to a shorted junction between a pair of the probes If this is the case the following message or similar will be displayed If all three probes are shorted or very low resistance then the following message will be displayed It is possible that the DCA Pro may detect one or more diode junctions or other component type within an unknown or faulty part...

Страница 8: ...age of about 0 25V The current at which the diode was tested is also displayed Unlike most multimeters that don t have a defined diode test current the DCA Pro typically tests diodes PN junctions at a forward current of 5mA You can test at different currrents by performing an I V graph using the PC software Note that the DCA Pro will detect only one diode even if two diodes are connected in series...

Страница 9: ...age of nearly 5 1V has been detected Additionally the forward biased voltage characteristic is measured 0 702V at 5mA for this example The DCA Pro attempts to test the Zener diode with a current of nominally 5mA For Zener diodes with a Zener voltage of more than about 7V a lower test current of 2mA or 1mA will be used This is illustrated in the following graph The DCA Pro may not be able to identi...

Страница 10: ...twork as text and as a component schematic symbol Types of diode network supported include Series pair Common Cathode and Common Anode It will then show the pinout and the VF specs for each diode in turn It can be seen in this example that the blue test clip is connected to both the anode on Diode 1 and to the cathode of Diode 2 This means that the two diodes are effectively connected in series wi...

Страница 11: ...he Blue test clip is connected to the Anode positive The forward voltage of the LED is measured at a nominal current of 5mA You can test at different currrents by performing an I V graph with the PC software During the analysis process the LED will briefly illuminate so you can see its illumination colour The test current of 5mA and the short pulse duration means that it may not be as bright as yo...

Страница 12: ... its Anode connected to the Blue test clip The forward bias characteristic is shown for LED 1 1 823V at 5mA in this example Pressing scroll off then shows the details for the 2nd LED in the bicolour LED package As expected for 2 lead bicolour LEDs we can see in this example that LED 2 has its connections in exactly the opposite configuration to LED 1 Note that it is common for the two LEDs within ...

Страница 13: ...The type of bicolour LED is shown here in this example we have a common cathode variety The pinout and VF specs for each internal LED are then shown It can be seen here that our example has its common cathode terminal connected to the Green test clip Typical values of forward voltage for LED colours are shown here LED types manufacturers will vary significantly LED Colour Typical VF 5mA Red 1 81V ...

Страница 14: ...ported The 3 test clips can be applied to the transistor in any configuration As an example testing a common PNP transistor such as the 2N5401 will result in a display similar to this This example shows that the Red test clip is connected to the Emitter the Green is connected to the Base and the Blue test clip is connected to the Collector Pressing scroll off allows further details to be displayed...

Страница 15: ...or large devices The displayed value of gain is very useful however for comparing transistors of a similar type for the purposes of gain matching or fault finding Darlington transistors can have very high gain values and more variation of gain will be evident as a result of this The current gain of transistor particularly germanium types can vary a large amount with changes in temperature Even the...

Страница 16: ... voltages as low as 0 2V Silicon types exhibit readings of about 0 7V and Darlington transistors can exhibit readings of about 1 2V because of the multiple base emitter junctions being measured The DCA Pro uses the VBE value to help it determine if your transistor is Silicon or Germanium There can be considerable overlap in VBE readings for Silicon and Germanium transistors Don t worry if the deci...

Страница 17: ...unt for the gain measurement unlike many multimeters gain measurement that can be fooled by leakage current If your transistor is a Silicon type you should expect to see a leakage current of close to 0 000mA unless the transistor is faulty Values less than 10μA are not displayed due to resolution limits The leakage current of germanium transistors can vary a large amount with changes in temperatur...

Страница 18: ...r the DCA Pro It is important to note that if a Darlington does contain a base emitter shunt resistor network any measurements of current gain hFE will be very low at the test currents used by the DCA Pro This is due to the resistors providing an additional path for the base current The readings for gain however can still be used for comparing transistors of a similar type for the purposes of matc...

Страница 19: ...eling diode has been detected it is shown on the schematic symbol Some examples are shown here The Philips BU505DF is a typical example of a diode protected bipolar transistor Remember that the diode if present is always internally connected between the collector and the emitter so that it is normally reverse biased For NPN transistors the anode of the diode is connected to the emitter of the tran...

Страница 20: ...ion represents the base terminal This is normal for situations where the current gain is so low that it is immeasurable at the test currents used by the DCA Pro Please note that the equivalent diode pattern may not be correctly identified by the DCA Pro if your transistor is a Darlington type or has additional diode s in its package such as a collector emitter protection diode This is due to the m...

Страница 21: ...rface mount packages and are becoming more common particularly in mass produced electronic products These devices are generally intended to be used with logic level signals 3V or 5V typically as such the gain of the device is rarely of concern The DCA Pro will identify the pinout the raw current gain and the voltage thresholds for turning the transistor on or off Additionally using V I slope analy...

Страница 22: ...urrent for both positive and negative gate source voltages up to the maximum allowed values of course typically 8V to 20V The first screen to be displayed gives information on the type of MOSFET detected and the pinout Pressing scroll off will then result in the gate threshold and other parameters of the MOSFET to be displayed The on gate threshold voltage is the gate source voltage at which condu...

Страница 23: ...ate source voltages Depletion Mode devices are characterised by the gate source voltage required to control the drain source current Modern Depletion Mode devices are generally only available in N Channel varieties and will conduct some current between its drain and source terminals even with a zero voltage applied across the gate and the source The device can only be turned completely off by taki...

Страница 24: ... often better than an equivalent sized MOSFET at high currents At low currents the saturation voltage of an IGBT is often worse than an equivalent sized MOSFET In this example we have an N Channel IGBT with an integral free wheeling diode Note the names of the leads Gate Collector and Emitter Similar to the MOSFET analysis the gate threshold is the voltage between the gate and emitter that causes ...

Страница 25: ...itter when there is zero voltage across the gate emitter terminals For an N Channel depletion mode IGBT the device can only be turned off fully if the gate terminal is taken more negative with respect to the emitter lead In this example we have an N Channel depletion mode IGBT with no free wheeling diode Note the negative gate threshold voltage characteristic of a depletion mode device The DCA Pro...

Страница 26: ... than 100MΩ the gate current can rise if the semiconductor junction between the gate and source or between the gate and drain become forward biased This can happen if the gate voltage becomes about 0 6V higher than either the drain or source terminals for N Channel devices or 0 6V lower than the drain or source for P Channel devices The internal structure of JFETs is essentially symmetrical about ...

Страница 27: ...ange in gate source voltage gfs ΔIDS ΔVGS The DCA Pro measures transconductance by determining the gate voltage change necessary to obtain a drain current change from 3 0mA to 5 0mA If the JFETs saturation current IDSS is less than 5 0mA then a proportionately lower current span will be used IDSS Drain Current for VGS 0 Finally the drain current for a zero gate source voltage is measured This is m...

Страница 28: ...a triac by checking the gate trigger quadrants that the device will reliably operate in Thyristors operate in only one quadrant positive gate current positive anode current Triacs can typically operate in three or four quadrants hence their use in AC control applications The gate trigger currents used by the DCA Pro are limited to less than 10mA Some thyristors and triacs will not operate at low c...

Страница 29: ...lators such as the popular 79L05 will be shown with a negative VOUT figure Some voltage regulators are not stable when used outside of their intended circuitry decoupling capacitors proper loads etc The DCA Pro may not be able to identify the regulator correctly if it is not stable during analysis The displayed drop out voltage VDO is the voltage that is required between input and output of the re...

Страница 30: ...nally ensure your PC meets the following requirements Windows XP SP3 Vista 7 8 10 or later 1GB RAM 1GB Hard Disk free Display size 1024 x 600 minimum typical netbook resolution 16 bit colour or better USB 1 1 or better NET framework 4 automatically installed if required Internet connection required for online updates Verified on UK localisation of Windows 10 at time of this user guide going to pri...

Страница 31: ...hen you may be prompted to download the NET package You need to accept the Microsoft agreement and the process will complete in a few minutes sometimes up to 10 minutes 4 When the DCA Pro software installation is complete you can plug in your DCA Pro to a convenient USB socket It s best to choose a socket directly on your computer rather than a hub After a few seconds you should be presented with ...

Страница 32: ...ed to accept the Microsoft agreement and the process will complete in a few minutes sometimes up to 10 minutes 4 Some systems may warn you that the driver is not signed The driver is in fact a standard Microsoft WinUSB driver that is set to look for the DCA Pro identifier so it is fine to accept the warning and proceed 5 When the DCA Pro software installation is complete you can plug in your DCA P...

Страница 33: ...our DCA Pro is connected and your software is running you should see the green message DCA Pro connected in the bottom left corner of the program window For the first time you use the software if you see the message DCA Pro disconnected then try unplugging the USB cable wait a few seconds and plug back in If that doesn t work depending on your version of Windows then you may need to restart your P...

Страница 34: ...tself Pressing Test in the PC software will initiate a component analysis in just the same way as pressing Test on the instrument itself Any test results are automatically passed to the PC software and displayed in a text window Additionally the component schematic and the colour coded pinout are also displayed Note that the component schematic is displayed in colour to illustrate which colour tes...

Страница 35: ...ow test parameters are applied You may not be able to perform curve tracing in the following circumstances Transistor gain is very low and the DCA Pro is unable to generate sufficient base current to obtain a sufficient span of collector current Transistor Darlington gain is extremely high which means that the tiny base currents cannot be generated with fine enough resolution If the component requ...

Страница 36: ...y of documenting important test results Simply right click on one of the curves and select Copy all All the raw measurement data that created the curves is now in the clipboard You can then paste the data into your spreadsheet This feature has been tested with Microsoft Excel SoftMaker PlanMaker and Apache Open Office Other spreadsheet programs should work fine too Once the raw data is pasted into...

Страница 37: ...firmware upgrade process doesn t succeed first time Windows sometimes takes time to prepare the built in HID driver that is used during the firmware upgrade process If the firmware upgrade process fails don t panic just try again it should be fine once Windows gets its built in driver initialised Peak guarantee to help you if you have any problems with upgrading using our official firmware LCD Con...

Страница 38: ...e Type Power up Rising 3 notes Power down including auto off Falling 3 notes Button press Very short blip Component detected Short Low High Faulty unknown or no part detected Long High Low If you wish you can switch the audible alerts on or off To change the current setting for audible alerts while the unit is already on simply press and hold the on test button for a few seconds The new sound sett...

Страница 39: ...ve the 3 screws remove the rear cover and change the battery while the unit is still resting face down We recommend using a high quality Alkaline NiMh or Lithium Iron Disulphide AAA cell such as LR03 or MN2400 1 5V Replace the cover take care not to pinch the test cables and carefully tighten the 3 screws DO NOT OVER TIGHTEN THE SCREWS Overload Protection The DCA Pro is protected against mild over...

Страница 40: ... parameters don t agree with the component data sheet Most semiconductors have very wide tolerances and even identical transistor types can show huge gain variation between them Characteristics shown in data sheets may be specified at different test conditions compared to the test conditions used by the DCA Pro My voltage regulator is not being identified Not all voltage regulators are stable when...

Страница 41: ... 1 79 μA 1 Accuracy 1 7 1 9μA 1 Current Drive 0 to 1 2mA Resolution 0 56 1 12 2 23 μA 1 Accuracy 1 7 2 4μA 1 Current Measurement 0 to 10mA Resolution 3 7 7 4 14 7 μA 1 Accuracy 1 7 15μA 1 Current Drive 0 to 10mA Resolution 4 6 9 2 18 3 μA 1 Accuracy 1 7 19μA 1 Load Current Measurement 0 to 12mA Resolution 6 6 13 1 26 2 μA 1 2 Accuracy 1 7 27μA 1 2 Load Current Drive 0 to 12mA Resolution 8 2 16 4 3...

Страница 42: ...5 mA VCE SAT accuracy 1 2 15mV IGBTs Enhancement mode VGE ON range 0 0 8 0 V 4 Depletion mode VGE ON range 5 0 0 0 V 4 VGE ON accuracy 1 2 19mV 4 Collector current at VGE ON 4 75 5 00 5 25 mA Collector emitter voltage at VGE ON 3 5 9 0 V 4 Acceptable gate emitter resistance 18 0 kΩ Collector saturation threshold for IGBT 0 35 0 4 0 45 V 8 VCE SAT collector test current 4 75 5 00 5 25 mA VCE SAT ga...

Страница 43: ...a LED decision at 5mA 1 50 4 00 V Zener Diodes Zener voltage range at 5mA 1 8 7 0 V Zener voltage range below 5mA 6 0 11 0 V Zener voltage accuracy 1 2 19mV Zener test current range 0 50 5 00 5 25 mA Voltage Regulators Input test voltage range IQ 2 0mA 1 1 10 0 V Input test voltage range IQ 4 0mA 8 0 V Acceptable quiescent current range IQ 0 0 6 0 mA Quiescent current accuracy 1 7 13 1μA Dropout v...

Страница 44: ...st circuit The test circuits that the DCA Pro uses to analyse various components are shown below These test circuits are presented here to assist in your understanding of the test conditions that are possible when testing in standalone mode and in the PC mode for curve tracing etc Transistor Test Circuit Example shown is for an NPN transistor Polarities are reversed for PNP devices ...

Страница 45: ...he gate source voltage can be driven negative by making the source voltage drive higher than the gate voltage drive When this is done however there is less voltage available to be across the drain source nodes and the load resistor Example shown is for an N Channel JFET Polarities are reversed for P Channel devices ...

Страница 46: ...ward and reverse characteristics of diodes Reverse characteristics are particularly useful for the testing of Zener diodes For the standalone mode the voltage is automatically adjusted to obtain a target current of 5mA For Zener diodes that have a breakdown voltage of more than about 7V then a lower test current will be used ...

Страница 47: ...regulators in this example Note that the range of regulator voltages supported will depend on the quiescent current IQ A higher quiescent current will cause more voltage to be dropped across the sense resistor and yield less voltage for the regulator itself Note also that some voltage regulators particularly low dropout types LDO are not stable when tested by the DCA Pro ...

Страница 48: ...sal Information WEEE Waste of Electrical and Electronic Equipment Recycling of Electrical and Electronic Products In 2006 the European Union introduced regulations WEEE for the collection and recycling of all waste electrical and electronic equipment It is no longer permissible to simply throw away electrical and electronic equipment Instead these products must enter the recycling process Each ind...

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