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Peak Atlas DCA55, User Manual

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DCA55 User Guide 

November 2021 – Rev 14 

Page 8 

 

Diode Networks 

 
The 

DCA55

  will  intelligently identify popular  types  of  three 

terminal  diode  networks.  For  three  terminal  devices  such  as 
SOT-23  diode  networks,  the  three  test  clips  must  all  be 
connected,  any  way  round.  The  instrument  will  identify  the  type  of  diode 
network  and  then  display  information  regarding  each  detected  diode  in 
sequence. The following types of diode networks are automatically recognised 
by the 

DCA55

: 

Both cathodes connected 
together, such as the BAV70 
device. 
 

Anodes of each diode are 
connected together, the 
BAW56W is an example. 
 

Here, each diode is connected 
in series. An example is the 
BAV99. 
 

Following the component identification, 
the details of each diode in the network 
will be displayed. 
 
Firstly,  the  pinout  for  the  diode  is 
displayed,  followed  by  the  electrical 
information,  forward  voltage  drop  and 
the  current  at  which  the  diode  was 
tested.  The  value  of  the  test  current 
depends  on  the  measured  forward 
voltage drop of the diode. 
 
Following  the  display  of  all  the  details  for  the  first  diode,  the  details  of  the 
second diode will then be displayed. 
 

Common cathode 

diode network

 

Common anode 

diode network

 

Series 

diode network

 

Pinout for D1...

 

RED GREEN BLUE 

Cath Anod

 

Forward voltage 

D1 Vf=0.642V

 

Summary of Contents for Atlas DCA55

Page 1: ...nalyser Model DCA55 Firmware 4 1 Designed and manufactured with pride in the UK User Guide Peak Electronic Design Limited 2000 2021 In the interests of development information in this guide is subject to change without notice E OE EN55 14 ...

Page 2: ...es 7 Diode Networks 8 LEDs 9 Bicolour LEDs 10 Bipolar Junction Transistors BJTs 11 Digital Transistors 18 Enhancement Mode MOSFETs 19 Depletion Mode MOSFETs 20 Junction FETs JFETs 21 Thyristors SCRs and Triacs 22 Taking care of your DCA55 23 Battery replacement 23 Self Tests 24 Appendix A Technical Specifications 25 Appendix B Statutory Information 28 This user guide has been written to accompany ...

Page 3: ...ower sensitive Triacs Low power sensitive Thyristors Light Emitting Diodes Bicolour LEDs Diodes Diode networks Automatic pinout identification just connect any way round only the gate is identified on JFETs Special feature identification such as diode protection and resistor shunts Gain measurement for bipolar transistors Leakage current measurement for bipolar transistors Silicon and Germanium de...

Page 4: ...d capacitors Failure to comply with this warning may result in personal injury damage to the equipment under test damage to the DCA55 and invalidation of the manufacturer s warranty The DCA55 is designed to analyse semiconductors that are not in circuit otherwise complex circuit effects will result in erroneous measurements Avoid rough treatment or hard knocks This unit is not waterproof Only use ...

Page 5: ...CA55 will start component analysis when the on test button is pressed 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 time each page can be displayed by briefly pressing the scroll off button The arrow symbol on the display indicates that more pages are available to be viewed Alth...

Page 6: ... 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 DCA55 may detect one or more diode junctions or other component type within an unknown or faulty part This is because many semiconductors comprise of PN diode junctio...

Page 7: ... of the diode technology In this example it is likely that the diode is a silicon diode A germanium or Schottky diode may yield a forward voltage of about 0 25V The current at which the diode was tested is also displayed Note that the DCA55 will detect only one diode even if two diodes are connected in series when the third test clip is not connected to the junction between the diodes The forward ...

Page 8: ...des of each diode are connected together the BAW56W is an example Here each diode is connected in series An example is the BAV99 Following the component identification the details of each diode in the network will be displayed Firstly the pinout for the diode is displayed followed by the electrical information forward voltage drop and the current at which the diode was tested The value of the test...

Page 9: ... voltage drop and the associated test current is displayed Here the Cathode ve LED terminal is connected to the Green test clip and the Anode ve LED terminal is connected to the Blue test clip In this example a simple green LED yields a forward voltage drop of 1 936V The test current is dependant on the forward voltage drop of the LED here the test current is measured as 3 047mA Some blue LEDs and...

Page 10: ...tails of each LED in the package will then be displayed in a similar way to the diode networks detailed earlier The pinout for the 1st LED is displayed Remember that this is the pinout for just one of the two LEDs in the package Interestingly the voltage drop for each LED loosely relates to the different colours within the bicolour LED It may therefore be possible to determine which lead is connec...

Page 11: ...onnected together the unit will display a similar message to this Note that the DCA55 will determine that the transistor under test is a Darlington type if the base emitter voltage drop is greater than 1 00V for devices with a base emitter shunt resistance of greater than 60k or if the base emitter voltage drop is greater than 0 80V for devices with a base emitter shunt resistance of less than 60k...

Page 12: ...s particularly CRT deflection transistors and many large Darlingtons have a protection diode inside their package connected between the collector and emitter The Philips BU505DF is a typical example of a diode protected bipolar transistor Remember that protection diodes are always internally connected between the collector and the emitter so that they are normally reverse biased For NPN transistor...

Page 13: ...e display will show Additionally the DCA55 will warn you that the accuracy of gain measurement hFE has been affected by the shunt resistor It is important to note that if a transistor 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 DCA55 This is due to the resistors providing an additional path for the base c...

Page 14: ...is is normal for situations where the current gain is so low that it is immeasurable at the test currents used by the DCA55 Please note that the equivalent diode pattern may not be correctly identified by the DCA55 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 multiple pn junctions that cannot be uniquel...

Page 15: ...in therefore may not represent the gain experienced at other collector currents and voltages This is particularly true for large devices Darlington transistors can have very high gain values and more variation of gain will be evident as a result of this Additionally it is quite normal for transistors of the same type to have a wide range of gain values For this reason transistor circuits are often...

Page 16: ...rmanium devices Germanium devices can have base emitter 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 Base Emitter voltage drop measurements can be useful when matching transistors Note that the DCA55 does not perform the base emitter tests at the same ...

Page 17: ... is typically 10μA 0 010mA For leakage currents higher than 10μA the measurement resolution is typically 2μA 0 002mA The maximum allowed leakage current for the DCA55 is 0 2mA for silicon devices and 1 75mA for germanium devices If the leakage current is more than that allowed value then the DCA55 may not detect your device correctly During the leakage current measurement the base emitter is autom...

Page 18: ...ithout the need for base current limiting resistors These parts are most often found in surface mount packages and are becoming more common particularly in mass produced electronic products The presence of the base resistor and the base emitter shunt resistor means that it isn t possible for the DCA55 to measure the gain of the device so only the device polarity NPN PNP and pinout is shown B C E N...

Page 19: ... these devices an insulated gate region that results in negligible gate current for both positive and negative gate source voltages up to the maximum allowed values of course typically 20V The first screen to be displayed gives information on the type of MOSFET detected Pressing scroll off will then result in the pinout of the MOSFET being displayed The gate source and drain are each identified An...

Page 20: ...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 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 ...

Page 21: ...input resistance between the gate and source is normally very high greater than 100M 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 ...

Page 22: ... 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 2 The test currents used by the DCA55 are kept low 5mA to eliminate the possibility of damage to a vast range of component types Some thyr...

Page 23: ...ding on your variant replace the battery with a good quality type that is identified on the rear label Rear Label AAA 1 5V Rear Label 23A MN21 12V AAA cell Alkaline NiMh or Lithium Iron Disulphide L1028 23A V23A GP23A MN21 Alkaline The battery can be replaced by placing your DCA55 face down on a smooth surface and removing the three screws from the rear of the unit After fitting of the new battery...

Page 24: ...ly If the problem was caused by a temporary condition on the test clips such as applying power to the test clips then simply re starting the DCA55 may clear the problem If a persistent problem does arise it is likely that damage has been caused by an external event such as excessive power being applied to the test clips or a large static discharge taking place If the problem persists please contac...

Page 25: ...rlington VBE range shunted 0 75V 0 80V 1 80V 4 Ge VBE range ICLEAK 10μA 0V 0 50V Ge VBE range ICLEAK 10μA 0V 0 55V Base emitter shunt threshold 50k 60k 70k Collector leakage test voltage 3 0V 4 0V 5 1V Collector leakage range 0 010mA 1 750mA Collector leakage resolution 1μA 2μA Collector leakage accuracy 2 4μA Si Acceptable leakage 0mA 0 2mA 6 Ge Acceptable leakage 0mA 1 75mA 6 MOSFETs Gate thresh...

Page 26: ...Secs Operating temperature range 15 C 35 C 10 60 F 95 F 10 Battery warning threshold 1 1V AAA Ver 9 0V GP23 Ver Battery life Typically 1300 operations 11 Dimensions body 103 x 70 x 20 mm 4 1 x 2 8 x 0 8 Notes 1 Between any pair of test clips 2 Collector current of 2 50mA and hFE 2000 3 Resistance across reverse biased base emitter 60k 4 Resistance across reverse biased base emitter 60k 5 Drain sou...

Page 27: ...DCA55 User Guide November 2021 Rev 14 Page 27 This page is intentionally blank Appendix B is on the rear cover of this user guide ...

Page 28: ... damage or abuse d Normal wear and tear The customer s statutory rights are not affected by any of the above All claims must be accompanied by a proof of purchase WEEE Waste of Electrical and Electronic Equipment Recycling of Electrical and Electronic Products It is not permissible to simply throw away electrical and electronic equipment Instead these products must enter the recycling process Each...

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