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Keithley 6485, User Manual

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Keithley 6485 User Manual Download Page 57

3

Measurements and 

Sourcing Voltage

•

Measurement overview

 — Explains the basic measurement and voltage source 

capabilities of Model 6485/6487. 

•

Performance considerations

 — Covers warm-up period, voltage offset correc-

tion, auto zero, zero check, and zero correct.

•

Current measurements

 — Provides a basic procedure to measure current.

•

Model 6487 ohms measurements

 — Covers methods to set up and use the ohms 

measurement function.

•

Model 6487 voltage source operation

 — Discusses configuring and using the 

voltage source.

Summary of Contents for 6485

Page 1: ...l 6487 Picoammeter Voltage Source User s Manual 6487 900 01 Rev B January 2003 A G R E A T E R M E A S U R E O F C O N F I D E N C E Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 0...

Page 2: ...TY This warranty does not apply to defects resulting from product modification without Keithley s express written consent or misuse of any product or part This warranty also does not apply to fuses so...

Page 3: ...l 6485 Picoammeter Model 6487 Picoammeter Voltage Source User s Manual 2003 Keithley Instruments Inc All rights reserved Cleveland Ohio U S A First Printing January 2003 Document Number 6487 900 01 Re...

Page 4: ...into the manual Addenda are numbered sequentially When a new Revision is created all Addenda associ ated with the previous Revision of the manual are incorporated into the new Revision of the manual E...

Page 5: ...cted to mains voltage or to voltage sources with high transient over voltages Measurement Category II connections require protection for high transient over voltages often as sociated with local AC ma...

Page 6: ...ages The symbol indicates a connection terminal to the equipment frame The WARNING heading in a manual explains dangers that might result in personal injury or death Always read the associated informa...

Page 7: ...ear panel summary 1 11 Analog output 1 12 Display 1 12 Status and error messages 1 12 Model 6487 front and rear panel familiarization 1 13 Model 6487 front panel summary 1 13 Model 6487 rear panel sum...

Page 8: ...a Model 487 and Model 6487 2 13 Analog output 2 14 Measurement considerations 2 15 3 Measurements and Sourcing Voltage Measurement overview 3 2 Current measurements 3 2 Model 6487 voltage source 3 2...

Page 9: ...ers 4 4 Median filter 4 5 Digital filter 4 5 Filter control 4 6 5 Relative mX b m X b reciprocal and log Relative 5 2 Front panel relative 5 2 SCPI programming relative 5 2 mX b m X b reciprocal and L...

Page 10: ...6 A Specifications B General MeasurementConsiderations Measurement considerations B 2 Ground loops B 2 Triboelectric effects B 3 Piezoelectric and stored charge effects B 3 Electrochemical effects B 4...

Page 11: ...purpose test fixture connections to Model 6485 2 10 Figure 2 11 General purpose test fixture connections to Model 6487 2 11 Figure 2 12 Typical connections for Model 6487 measurements using the Model...

Page 12: ...easurements 3 8 Table 3 5 SCPI commands basic Model 6487 ohms measurements 3 11 Table 3 6 Voltage source current limits 3 13 Table 3 7 SCPI commands voltage source 3 14 4 Range Units Digits Rate and F...

Page 13: ...on Summarizes the controls and connectors of the Model 6485 as well as providing information on the front panel display Model 6487 front and rear panel familiarization Summarizes the controls and conn...

Page 14: ...Measurements and Sourcing Voltage Model 6487 only Section 4 Range Units Digits Rate and Filters Section 5 Relative mX b m X b reciprocal and log Section 6 Buffer and Sweeps Section 7 Remote Operation...

Page 15: ...eath Always read the associated information very carefully before performing the indicated procedure The CAUTION heading used in this manual explains hazards that could damage the instrument Such dama...

Page 16: ...nuals Model 6487 The following items are included with every Model 6487 order Model 6487 Picoammeter with line cord Triax Protective Shield Cap CAP 31 7078 TRX 3 Triax cable Model 8607 1kV Source Bana...

Page 17: ...triax tee adapter for use with 7078 TRX triax cables Suitable for use with the Model 6487 V Source in high voltage applications Model 237 TRX TBC Connector This is a 3 lug female triax bulkhead connec...

Page 18: ...S 232 and trigger link cables and adapters Models 7007 1 and 7007 2 shielded GPIB cables Connects the Model 6485 6487 to the GPIB bus using shielded cables and connectors to reduce electromagnetic int...

Page 19: ...5 6487 Includes handles and shoulder strap Additional references While reading this document you may find it helpful to consult the following documenta tion for reference Model 6485 Instruction Manual...

Page 20: ...rnal buffer Section 6 Limits Set up to two stages of high and low reading limits to test devices see Section 8 of the Model 6485 Instruction Manual or Model 6487 Reference Manual Digital I O port Mode...

Page 21: ...LOCAL When in Remote operation REM annunciator lit cancels GPIB remote mode MENU Provides access to menu POWER Power switch In position turns 6485 on I out position turns it off O 2 Function keys MED...

Page 22: ...NTER Use to accept selection and move to next choice or back to measurement display 4 Range keys Use to select the next higher measurement range Also use to modify the upper auto range limit Use to se...

Page 23: ...32 MADE IN U S A 220V PK ANALOG OUT 1 3 8 4 5 6 7 2 1 INPUT This standard female BNC connector is used to connect the signal to be measured to the input of the Model 6485 Mates to a BNC cable 2 CHASSI...

Page 24: ...t on the rear panel The ANALOG OUT provides a scaled inverting 2V output A full scale reading corresponds to 2V output See Ana log output page 2 14 in for full details on analog output operation Displ...

Page 25: ...keys and power switch and then the key Not all keys have configurable properties 1 Special keys and power switch CONFIG When in Local operation use to configure properties of the next button pressed L...

Page 26: ...tart buffer and modify the number of readings to store RECALL Use to display stored readings including maximum minimum peak to peak average and standard deviation The and RANGE keys scroll through the...

Page 27: ...Instrument addressed to listen over GPIB MATH mX b m X b or log10 calculation enabled MED Medium 1 PLC reading rate selected REL Relative enabled for present measurement function REM Instrument in GPI...

Page 28: ...505V PK 505V PK 1 2 3 4 5 6 7 8 9 10 11 12 1 INPUT This standard three lug female triax connector is used to connect the signal to be measured to the input of the Model 6487 Mates to a three slot mal...

Page 29: ...panel operate indicator is on CAUTION Do not connect external sources to the 6487 voltage source External sources may damage the 6487 voltage source 10 V SOURCE OUTPUT HI This standard banana connecto...

Page 30: ...ts or scientific notation Annunciators indi cate various states of operation See Model 6487 front panel summary page 1 13 for a complete listing of display annunciators The normal display also include...

Page 31: ...ed AC outlet WARNING The power cord supplied with the Model 6485 6487 contains a sepa rate ground terminal for use with grounded outlets When proper con nections are made instrument chassis is connect...

Page 32: ...self tests the firmware revision levels are displayed For example 6485 A01 or 6487 A01 3 After the firmware revision levels are displayed the detected line frequency is displayed For example FREQ 60H...

Page 33: ...ctory default setup is saved into the USR0 USR1 and USR2 setups Saving user setups To save a user setup configure Model 6485 6487 for the desired measurement applica tion then press SAVE and select th...

Page 34: ...abled No effect Digital Filter AVG Count Type Off 10 Moving Display Resolution DIGITS 5 digits Format byte order Swapped Normal GPIB Address Language No effect On at factory No effect 14 at factory No...

Page 35: ...rig In Source Event Trigger Count Trigger Delay Input Trigger Link Line Source Bypass Output Trigger Link Line IMM 1 0 1 NEVER 2 Units No effect Zero Check Enabled Zero Correct Disabled Table 1 1 cont...

Page 36: ...Off 10 Moving Display Resolution DIGITS 5 digits Format byte order Swapped Normal Function Amps GPIB Address Language No effect On at factory No effect 22 at factory No effect SCPI at factory Limit T...

Page 37: ...2 Units No effect Voltage Source Operate Amplitude Range Current Limit 10V Range Interlock Sweeps Start Voltage Stop Voltage Step Voltage Center Voltage Span Voltage Delay Off 0V 10V 25mA Off 0V 10V 1...

Page 38: ...on REM annunciator is lit pressing the menu key has no effect Press the LOCAL key to place the unit in local operation then press the MENU key to access the menu items Table 1 3 Model 6485 MENU struct...

Page 39: ...xclusively to remote operation is provided after each table The SCPI tables may refer ence you to other sections of this manual NOTE SCPI tables in this manual are abridged That is they do NOT include...

Page 40: ...1 28 Getting Started Model 6485 and 6487 User s Manual...

Page 41: ...ohms measurements Using a test fixture Discusses using general test fixtures as well as the Model 8009 test fixture Model 6487 interlock Provides information on using the Model 6487 interlock which mu...

Page 42: ...se input cables page 2 3 Figure 2 1 Model 6485 BNC Input connector Shield LO or GND Input Center Conductor CAT I INPUT Maximum input levels The maximum input levels to the Model 6485 are summarized in...

Page 43: ...on measurements you should always use low noise cables As a gen eral rule always use the shortest possible cable for measurements See Model 6485 input cables connectors and adapters page 1 4 for recom...

Page 44: ...ource or ammeter common and chassis ground common mode voltage is 505V peak Exceeding this voltage can create a shock hazard Figure 2 4 Model 6487 maximum input levels Input HI Input LO 505V Peak Chas...

Page 45: ...nnection between input LO and the external voltage source be sufficiently low impedance and capable of carrying the short circuit current of the source in order that the LO not exceed 42V CAUTION Curr...

Page 46: ...cuit current of the source in order that the LO not exceed 42V CAUTION The LO to chassis breakdown voltage is 500V Exceeding this voltage may cause damage to the instrument Figure 2 6 Shielding for Mo...

Page 47: ...cuit current of the source in order that the LO not exceed 505V CAUTION Current limiting resistors are required for DUTs capable of forcing voltages 505V or greater Damage to the instrument may result...

Page 48: ...d Model 6487 chassis This type of shielding should be used whenever hazardous voltages will be present in the test circuit WARNING The maximum safe voltage between picoammeter LO and chassis ground co...

Page 49: ...s or when the 6485 6487 auto ranges up to these ranges as a response to the applied voltage if the input voltage exceeds 60V the Model 6485 6487 will change from a current limit to a 1M 3M input imped...

Page 50: ...e 2 11 This test fixture will accommodate a variety of connection requirements Figure 2 10 General purpose test fixture connections From External Power Supply To 6485 Input Metal Guard Plate Banana Ja...

Page 51: ...er to Figure 2 12 Figure 2 12 Typical connections for Model 6487 measurements using the Model 8009 test fixture METER SOURCE LID INTERLOCK METER SOURCE LID INTERLOCK TRIAX XXX MAX HI LO MAX INPUT XXXX...

Page 52: ...NTERLOCK connector as shown When the switch is open the interlock is asserted and the voltage source cannot be placed in operate on the 50V or 500V voltage source ranges and option ally for the 10V ra...

Page 53: ...hibited with Open Switch Test Fixture How is the interlock different between a Model 487 and Model 6487 The Model 487 uses a 3 pin DIN interlock connector while the Model 6487 uses a 4 pin DIN for the...

Page 54: ...output CAUTION Connecting COMMON or ANALOG OUT to earth while floating the input may damage the instrument Connections for using this output are shown in Figure 2 14 Model 6485 and Figure 2 15 Model 6...

Page 55: ...SB 220 VAC 240 VAC 505V PK 505V PK 505V PK Model 6487 Rear Panel Measuring Device i e Chart recorder LO HI Measurement considerations There are a variety of factors to consider when making low level...

Page 56: ...n between a conductor and the surrounding insulator i e bending a triax cable Piezoelectric and stored charge effects Currents generated by mechanical stress on certain insulating materials Electroche...

Page 57: ...considerations Covers warm up period voltage offset correc tion auto zero zero check and zero correct Current measurements Provides a basic procedure to measure current Model 6487 ohms measurements C...

Page 58: ...ns Appendix A Table 3 1 Basic Model 6485 and 6487 current measurement capabilities Function Reading Range Available Ranges Amps 10fA to 21mA 2nA 20nA 200nA 2 A 20 A 200 A 2mA and 20mA Model 6487 volta...

Page 59: ...del 6485 6487 periodically measures internal voltages corresponding to offsets zero and amplifier gains a process known as autozeroing With autozero disabled measurement speed increases up to three ti...

Page 60: ...iator indicates that the displayed reading is zero corrected 6 To turn off zero correct press ZCOR Model 6485 or REL Model 6487 again with zero check enabled NOTES With regard to the zero correct feat...

Page 61: ...mage to the instrument The maximum input voltage and current to Model 6485 is 220V peak and 21mA Exceeding either of these values may cause damage to the instrument that is not covered by the warranty...

Page 62: ...to select a manual measurement range or press AUTO to enable auto range With auto range enabled the instrument will automatically go to the most sensitive range to make the measurement See Section 4 f...

Page 63: ...ring is cov ered in Section 4 Figure 3 1 Connections for Model 6485 current measurements 220V Peak 4801 4802 10 or 4803 Input Metal Safety Shield Metal Noise Shield 120 FUSE LINE 630mA LINE RATING 50...

Page 64: ...232 MADE IN U S A ANALOG OUT DIGITAL I O INTERLOCK 505V MAX V SOURCE OUTPUT 505V PK TO CHASSIS LO HI FUSE LINE 630mAT SB 100 VAC 120 VAC 315mAT SB 220 VAC 240 VAC 505V PK 505V PK 505V PK SCPI programm...

Page 65: ...the measured resistance from the voltage source value and the measured current R V I When setting up the voltage source choose as high a voltage value as possible for maximum current keeping in mind...

Page 66: ...ance under test WARNING A safety shield is advisable whenever measurements are being made with voltages over 30V DC Connections for the safety shield are shown in Figure 3 3 The metal safety shield mu...

Page 67: ...5mAT SB 220 VAC 240 VAC 505V PK 505V PK 505V PK DUT DUT Device Under Test Model 6487 V SOURCE OUTPUT SCPI programming Table 3 5 SCPI commands basic Model 6487 ohms measurements Commands Description SE...

Page 68: ...WEEP mode Select DC for normal operation See Section 6 for details on sweeps After the mode is selected the display shows a full resolution value of the voltage source with the left most position high...

Page 69: ...rned off Rather it is in a state that acts just like the voltage source was programmed to 0V on the selected range It will enter this state on power up after the VOLTAGE SOURCE OPERATE light blinks In...

Page 70: ...T b SOUR VOLT INT FAIL Set the source output level 500 to 500V Set source range to one of three ranges 10 50 and 500V Set the source current limit 2 5e 5 2 5e 4 2 5e 3 or 2 5e 2 1 Enable ON or disable...

Page 71: ...I commands for remote operation Rate Provides details on reading rate selection Includes the SCPI commands for remote operation Model 6487 damping Provides details on damping rate selection Includes t...

Page 72: ...strument automatically goes to the most sensitive available range to measure the applied signal Up ranging occurs at 105 of range while down ranging occurs at the range value The AUTO key toggles the...

Page 73: ...ment ranges To set display resolution press and release the DIGITS key until the desired num ber of digits is displayed NOTE For the Model 6487 the voltage source value will not be displayed in the 6...

Page 74: ...d by high capacitance for current measurements However damping will also slow down the response of the measurement To enable or disable damping from the front panel simply press the Model 6487 DAMP ke...

Page 75: ...2 R 1 where R is the selected rank 1 to 5 Note that the median filter throws out the oldest of the ranked values It is especially use ful for noise characterized by unwanted spikes Digital filter Digi...

Page 76: ...u can choose ON or OFF and set the RANK 1 5 For the AVERAGE filter you can choose ON or OFF COUNT 2 100 MOVING or REPEAT Once the filter is configured you can toggle the filter state on or off by pres...

Page 77: ...tive Explains how to null an offset or establish a baseline value Includes the SCPI commands for remote operation mX b m X b reciprocal and Logarithmic Covers these three basic math operations and inc...

Page 78: ...he present reading disable zero check display the reading then press REL The REL annunciator will turn on and subsequent readings will be the difference between the actual input and the Rel value To d...

Page 79: ...ically according to the following calculations Y mX b Y m X b where X is the normal display reading m and b are user entered constants for scale factor and offset Y is the displayed result NOTE Changi...

Page 80: ...the math function is enabled SCPI programming mX b m X b and log Table 5 2 SCPI commands mX b m X b and log Commands Description CALC FORM name CALC KMAT MMF n CALC KMAT MBF n CALC KMAT MUN name CALC...

Page 81: ...6 BufferandSweeps Buffer operations Explains how to store and recall readings including buffer statistics Model 6487 voltage sweeps Discusses how to generate sweeps using the volt age source...

Page 82: ...based on the readings of the different measurement functions Store To store readings set up the instrument for the desired configuration then press CONFIG followed by STORE Set the number of readings...

Page 83: ...quickly Press ENTER with a reading count of 0 displayed to finish clearing the buffer Buffer statistics MIN and MAX provides the minimum and maximum readings stored in the buffer It also indicates the...

Page 84: ...ings actually stored in buffer Select source of readings for buffer SENS CALC1 or CALC2 Select buffer control mode NEV or NEXT Select timestamp format ABS or DELT Read all readings in buffer Specify d...

Page 85: ...ings will be stored in the buffer for later recall see Recall page 6 2 To abort a sweep in progress press the EXIT key SCPI programming sweeps NOTE When programming sweeps via remote the arm count may...

Page 86: ...defaults SOUR VOLT SWE STAR 1 Start voltage 1V SOUR VOLT SWE STOP 10 Stop voltage 10V SOUR VOLT SWE STEP 1 Step voltage 1V SOUR VOLT SWE DEL 0 1 0 1s delay ARM COUN INF Reset arm count FORM ELEM READ...

Page 87: ...nd configuring an interface Explains how to select and configure an interface GPIB or RS 232 Remote commands Lists the following types of bus commands general bus commands common commands signal orien...

Page 88: ...address con flicts Use the SCPI language setting for most applications See the Model 6485 Instruc tion Manual or Model 6487 Reference Manual for information on the DCC and 488 1 programming languages...

Page 89: ...NU IEEE 488 CAT I TRIGGER LINK RS 232 MADE IN U S A 220V PK ANALOG OUT IEEE 488 RS 232 s Figure 7 2 Model 6487 IEEE 488 and RS 232 connector location 120 LINE RATING 50 60Hz 50 VA MAX INPUT CHANGE IEE...

Page 90: ...cator and returns the display to nor mal if a user defined message was displayed If the unit is in LOCAL not in remote the LOCAL key acts as a configure key see Model 6485 front panel summary page 1 8...

Page 91: ...l number of any installed options RCL NRf Recall command Returns Model 6485 6487 to the user saved setup RST Reset command Returns Model 6485 6487 to the RST default conditions SAV NRf Save command Sa...

Page 92: ...check correct line frequency error messages Buffer operation and data Instrument triggering Programming syntax The following paragraphs cover syntax for both common commands and SCPI com mands For mor...

Page 93: ...Select a parameter name from a listed group NRf Numeric representation format A number that can be expressed as an integer e g 8 a real number e g 23 6 or an exponent 2 3E6 NDN Non decimal numeric A n...

Page 94: ...7 8 Remote Operation and Commands Model 6485 and 6487 User s Manual...

Page 95: ...A Specifications...

Page 96: ...SH1 AH1 T5 TE0 L4 LE0 SR1 RL1 PP0 DC1 DT1 C0 E1 PROGRAMMABLE PARAMETERS Range Zero Check Zero Correct EOI DDC mode only Trigger Terminator DDC mode only Calibration SCPI mode only Display Format SRQ R...

Page 97: ...zero off 2 Binary transfer mode IEEE 488 1 3 Measured from trigger in to meter complete TEMPERATURE COEFFICIENT 0 18 C 28 50 C For each C add 0 1 rdg offset to accuracy spec INPUT VOLTAGE BURDEN 200...

Page 98: ...A 4 Specifications Model 6485 and 6487 User s Manual...

Page 99: ...B GeneralMeasurement Considerations Measurement considerations lists and defines nine types of measurement considerations...

Page 100: ...atic or erroneous measurements The configuration shown in Figure B 1 intro duces errors in two ways Large ground currents flowing in one of the wires will encounter small resistances either in the wir...

Page 101: ...nductor HI and its surrounding insulator resulting in triboelectric currents Triboelectric currents can be minimized as follows Use low noise cables These cables are specially designed to minimize cha...

Page 102: ...ht Some components such as semiconductor junctions and MOS capacitors on semiconductor wafers are excellent light detectors Consequently these components must be tested in a light free environment Whi...

Page 103: ...uces the amount of electrostatic interference seen in the measurement Magnetic fields A magnetic field passing through a loop in a test circuit will generate a magnetic EMF voltage that is proportiona...

Page 104: ...st leads will often reduce EMI to an acceptable level In extreme cases a specially constructed screen room may be required to sufficiently attenuate the troublesome signal External filtering of the in...

Page 105: ...C ExamplePrograms Programming examples lists and defines three types of programming exam ples...

Page 106: ...count to 2000 NPLC 01 Set integration rate to 01 PLC RANG 002 Use 2mA range SYST ZCH OFF Turn zero check off SYST AZER STAT OFF Turn auto zero off DISP ENAB OFF Turn display off CLS Clear status model...

Page 107: ...ANG 488 1 then press ENTER See instruction or reference manual for details RST Return 6485 6487 to RST defaults FORM ELEM READ Return readings only FORM BORD SWAP Set for swapped byte order FORM DATA...

Page 108: ...TRIG COUN 1500 Set trigger count to 1500 NPLC 01 Set integration rate to 01 PLC RANG 002 Use 2mA range SYST ZCH OFF Turn zero check off CLS Clear status model TRAC POIN 3000 Set buffer size to 3000 TR...

Page 109: ...nectors 1 4 1 5 Contact information 1 3 CS 565 barrel adapter 1 5 Current 3 2 D DAMP 1 14 damping 4 4 DC and alternating voltage ohms 3 9 Default settings 1 21 detected line frequency 1 20 DIGITAL 1 1...

Page 110: ...noise input cables 2 3 2 4 LSTN 1 10 1 15 M M X B 1 9 Magnetic fields B 5 Manual ranging 4 2 MATH 1 10 1 15 Maximum input levels 2 2 2 4 measurement 2 16 Measurement considerations 2 14 B 2 Measuremen...

Page 111: ...4 6 Restoring 1 21 RS 232 1 12 1 17 connections 7 2 RS 232 7 2 RS 232 interface 7 2 S Safety interlock 2 13 safety shield 3 6 3 10 Safety symbols and terms 1 3 SAVE 1 10 1 14 Saving 1 21 scientific SC...

Page 112: ...V V 1 17 Voltage 1 17 2 4 3 3 3 13 voltage 3 12 W Warm up period 3 3 Warranty 1 2 Warranty information 1 2 Z ZCHK 1 9 1 13 ZCOR 1 9 Zero 3 3...

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Page 115: ...the property of Keithley Instruments Inc All other trademarks and trade names are the property of their respective companies A G R E A T E R M E A S U R E O F C O N F I D E N C E 12 04 uments Inc R E...

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