ASTM_F_676_-_97_2003.pdf

Designation:F 676 97(Reapproved 2003)Standard Test Method forMeasuring Unsaturated TTL Sink Current1This standard is issued under the fixed designation F 676;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 the unsat-urated sink current of transistor-transistor logic(TTL)devicesunder specified conditions.1.2 UnitsThe values stated in the International System ofUnits(SI)are to be regarded as standard.No other units ofmeasurement are included in this standard.1.3 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.Referenced Documents2.1 ASTM Standards:E 178 Practice for Dealing with Outlying Observations23.Summary of Test Method3.1 Input and bias voltage levels and any required inputsignals are applied to the device under test to put the output tobe tested in the low-level state.Voltage pulses of sufficientmagnitude to pull the output transistor out of saturation areapplied to the output pin under test.The corresponding currentpulses are measured.3.2 The following test conditions are not specified by thetest method and shall be agreed upon by the parties to the test:3.2.1 The output pin(s)to be tested,3.2.2 Ambient temperature range,3.2.3 Supply voltage(s)to be used,3.2.4 Input sequence to be applied before the device outputis pulsed,3.2.5 Pulse voltage to be applied to the output pin under test,3.2.6 Duty cycle and duration of the applied pulses,and3.2.7 Accuracy and tolerances required for supply volt-age(s),input voltages,pulse voltage,current measurement,duty cycle,and pulse-width.4.Significance and Use4.1 Unsaturated sink current is a special parameter that isclosely related to the gain of the output transistor of TTLcircuits.This parameter is particularly useful in evaluatingneutron degradation in TTL devices because it changessmoothly as the device degrades,and exhibits larger changes atmoderate radiation levels than the standard electrical param-eters.5.Interferences5.1 Long pulses will cause many current probes to saturate.The current-time rating of the probe must not be exceeded.5.2 Valid measurements will not be obtained unless thevoltage applied to the output is sufficient to bring the outputtransistor out of saturation.5.3 If the voltage applied to the output exceeds 1.5 V,errorsmay result.Some devices may change state.Some deviceshave internal diode connections which will conduct if theoutput exceeds 1.5 V.5.4 High contact resistance will cause the voltage at thedevice to differ from the applied voltage.Kelvin contacts maybe required.5.5 Device temperature will affect this measurement.Pulsewidth and duty cycle must be maintained low enough that thetest does not cause heating of the device.6.Apparatus6.1 Pulse Generator,capable of supplying the currentrequired by the output pin under test at the agreed-uponvoltage.6.2 Oscilloscope,or Digital Recorder,dual-beam or dual-trace,meeting the following requirements:6.2.1 Bandwidth of 30 MHz or greater.6.2.2 Deflection factor range of 5 mV per division to 1 V perdivision.6.3 Termination RT,suitable for the current probe used.6.4 Current Probe,meeting the following requirements:6.4.1 Rise time less than 10%of the agreed-upon pulsewidth.6.4.2 Droop no more than 5%of the agreed-upon pulsewidth.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.11 on Quality andHardness Assurance.Current edition approved Dec.10,1997.Published March 1998.Originallypublished as F 676 80.Last previous edition F 676 93.21983 Annual Book of ASTM Standards,Vol 14.02.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.6.4.3 Current-time rating sufficient to avoid saturation.See4.1.6.5 Power Supplies and Pulse Generators,as required toestablish bias and input conditions for the test.6.6 Oscilloscope Probe,having an input impedance of 1MV or greater in parallel with 25 pF or less.6.7 Miscellaneous Circuit Components,to be used as re-quired to set up the test circuit.See Fig.1.All componentsshall be of a quality customarily used in electronic circuitfabrication.6.8 Temperature-Measuring Device,capable of measuringthe temperature in the vicinity of the device under test to anaccuracy of 6 1C at the temperature specified for themeasurement.7.Sampling7.1 This test method determines the properties of a singlespecimen.If sampling procedures are used to select devices fortest,the procedures shall be agreed upon by the parties to thetes