ASTM_F_528_-_99.pdf

Designation:F 528 99Standard Test Method ofMeasurement of Common-Emitter D-C Current Gain ofJunction Transistors1This standard is issued under the fixed designation F 528;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the measurement of common-emitter d-c current gain(forward,hFE,or inverted,hFEI)ofbipolar transistors,for which the collector-emitter leakagecurrent,ICEO,is less than 10%of the collector current,IC,atwhich the measurement is to be made,and for which the shuntleakage current in the base circuit is less than 10%of the basecurrent required.1.2 This test method is suitable for measurement ofcommon-emitter d-c current gain at a single given value of testtransistor collector current or over a given range of collectorcurrents(for example,over the range of the transistor to betested).1.2.1 The nominal ranges of collector current over whichthe three test circuits are intended to be used are as follows:1.2.1.1 Circuit 1,less than 100 A,1.2.1.2 Circuit 2,from 100 A to 100 mA,and1.2.1.3 Circuit 3,greater than 100 mA.1.3 This test method incorporates tests to determine if thepower dissipated in the transistor is low enough that thetemperature of the junction is approximately the same as theambient temperature.1.4 The values stated in International System of Units(SI)are to be regarded as standard.No other units of measurementare included in this standard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Terminology2.1 Definitions:2.1.1 common-emitter d-c current gain,hFEthe ratio ofd-c collector current(in excess of collector-emitter leakagecurrent ICEO)to base current when the transistor is connectedin the common-emitter configuration(see Fig.1a);that is:hFE5IC2 ICEO!/IB2.1.2inverted common-emitter d-c current gain,hFEItheratio of d-c emitter current IE(in excess of emitter-collectorleakage current IECO)to base current when the transistor isconnected in the common-collector configuration(see Fig.1b);that is:hFEI5IE2 IECO!/IBNOTE1In the remainder of this test method only hFEis discussed.Measurements and calculations for hFEIare identical and the sameapparatus and procedures apply.3.Summary of Test Method3.1 Sufficient current,IB,is driven into the base of atransistor to achieve the desired collector current at therequired collector-emitter voltage.The magnitude of the basecurrent is measured and the gain calculated.Three test circuitsare available for tests at low,intermediate,and high transistorcollector currents,respectively.The measurements and calcu-lations are repeated for all collector-current values of interest.3.2 The following quantities are unspecified in the1This test method is under the jurisdiction of ASTM Committee F-1 onElectronics,and is the direct responsibility of Subcommittee F01.11 on Quality andHardness Assurance.Current edition approved Dec.10,1999.Published February 2000.Originallypublished as F 528 77 T.Last previous edition F 528M 95.NOTE1The transistor shown is an npn type;for pnp types thepolarities of the bias supplies are reversed.FIG.1 Explanatory Circuits to Illustrate the Meaning of TermsUsed in Calculation ofhFEandhFEI1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.method and are to be agreed upon by the parties to the test:3.2.1 The collector currents,IC,at which the measurementsare to be made,3.2.2 The collector-emitter voltage,VCE,to be used whenmaking the measurements,and3.2.3 The temperature at which the measurements are to bemade.4.Significance and Use4.1 The current gain of a transistor is basic to its operationand is its single most important parameter.4.2 Ionizing radiation,that is,gamma radiation due to anuclear burst,will degrade the current gain due to lifetimedamage in the bulk material.Degradation of gain will begreatest immediately following a burst of ionizing radiationand the gain will rapidly recover to a quasi steady-state value.Defect annealing may continue for weeks but usually thecurrent gain recovery is small or negligible.4.3 This method provides a procedure that does not requirespecial-purpose test equipment.4.4 This method is suitable for use for specification accep-tance,service evaluation,or manufacturing control.5.Interferences5.1 Shunt Leakage When the magnitude of the impedancebetween the base and emitter connections on the test fixture iscomparable to the base-emitter impedance of the transistorbeing tested,the measurement results are invalid.NOTE2The shunt leakage current can be affected by high humi