Keithley 238 Service Manual
Model 238 High Current
Source Measure Unit
Service Manual
Contains Servicing Information
WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year
from date of shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable
batteries, diskettes, and documentation.
During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio.
You will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service
facility. Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for
the balance of the original warranty period, or at least 90 days.
LIMITATION OF WARRANTY
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, software, non-rechargeable batteries, damage from
battery leakage, or problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY
IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT,
INDIRECT, SPECIAL, INCIDENT’ OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS
INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE
OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY
PERSON. OR DAMAGE To PROPERTY.
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10199
Model 238 High Current Source Measure Unit
Service Manual
01990, Keithley instruments, Inc.
Test Instrument Group
All rights reserved.
Cleveland, Ohio, U.S.A.
Third Printing, May 2000
Document Number: 238-902-01 Rev. C
Manual Print History
The print history shown below lists the printing dates of all Revisions and Addenda created for this manual. The
Revision Level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are
released between Revisions, contain important change information that the user should incorporate immediately into
the manual. Addenda are numbered sequentially. When a new Revision is created, all Addenda associated with the
previous Revision of the manual are incorporated into the new Revision of the manual. Each new Revision includes
a revised copy of this print history page.
Revision B (Document Number 238-902-01)
Revision C (Document Number 238-902-01)
..................................................
......................................................
August 1992
May 2000
All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand and product names are trademarks or registered trade.marks of their respective holders.
Safety Precautions
The following safety precautions should be observed before using
this product and any associated instrumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions
may be present.
This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury. Read the operating information
carefully before using the product.
The types of product users are:
Responsible body is the individual or group responsible for the use
and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for ensuring that operators are adequately trained.
Operators use the product for its intended function. They must be
trained in electrical safety procedures and proper use of the instrument. They must be protect&J from electric shock and contact with
hazardous live circuits.
Maintenance personnel perform routine procedures on the product
to keep it operating, for example, setting the line voltage or replacing consumable materials. Maintenance procedures are described in
the manual. The procedures explicitly state if the operator may perform them. Otherwise, they should be performed only by service
personnel.
Service personnel are trained to work on live circuits, and perform
safe installations and repairs of products. Only properly trained service personnel may perform installation and service procedures.
Users of this product must be protected from electric shock at all
times. The responsible body must ensure that users are prevented
access and/or insulated from every connection point. In some cases,
connections must be exposed to potential human contact. Product
users in these circumstances must be trained to protect themselves
from the risk of electric shock. If the circuit is capable of operating
at or above 1000 volts, no conductive part of the circuit may be
exposed.
As described in the International Electrotechnical Commission
@EC) Standard IEC 664, digital multimeter measuring circuits
(e.g., Keithley Models 175A. 199,2000,2001,2002. and 2010) are
Installation Category II. All other instruments’ signal terminals are
Installation Category I and must not be connected to mains.
Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When connecting sources to switching cards, install protective devices to limit fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.
For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables orjump-
ers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.
Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connectorjacks or test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present. A good safety practice is to expect
that hazardous voltage is present in any unknown circuit before
measuring.
Do not touch any object that could provide a current path to the
common side of the circuit under test or power line (earth) ground.
Always make measurements with dry hands while standing on a
dry, insulated surface capable of withstanding the voltage being
measured.
The instrument and accessories must be used in accordance with its
specifications and operating instructions or the safety of the equip
ment may be impaired.
The WARNING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure.
Do not exceed the maximum signal levels of the instruments and accessories, as defined in the specifications and operating information, and as shown on the instrument or test fixture panels, or
switching card.
When fuses are used in a product, replace with same type and rating
for continued protection against fire hazard.
Chassis connections must only be used as shield connections for
measuring circuits, NOT as safety earth ground connections.
If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation requires the use of a
lid interlock.
Ifa@ screw is present, connect it to safety earth ground using the
wire recommended in the user documentation.
The ! A symbol on an instrument indicates that the user should refer to the operating instructions located in the manual.
The
symbol on an instrument shows that it can source or mea-
m
sure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.
The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and
all test cables.
To maintain protection from electric shock and lire. replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that selected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.
To clean an instrument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill
on the instrument. Products that consist of a circuit board with no
case or chassis (e.g., data acquisition board for installation into a
computer) should never require cleaning if handled according to in-
structions. If the board becomes contaminated and operation is af-
fected, the board should be returned to the factory for proper
cleaning/servicing.
Rev. 10199
Model 238 Source Measure Unit Specifications
SOURCE-MEASURE UNIT: Sources voltage while measuring current, or
sources current while measuring voltage.
FUNCTION: Can be used as DC source or meter, sweep source, or full
source-measure unit.
SOURCE-DELAY-MEASURE CYCLE:
Source
- Source-Delay-Measure Cycle - -
Default
I I
Delay
Default Delay: Fixed delay for instrument settling.
User Delay: Additional delay for device under test or system capaci-
tance.
MEASURE:
Integration Time:
Fast 416 psec.
Medium
Line Cycle
Elapsed Time: Measures and stores time from sweep trigger to mea-
surement complete for each step of sweep.
RANGING:
Source: Auto-ranging through keypad entry; fixed range selectionusing
rotary dial and SELECT keys (DC function). Fully programmable in
SWEEP function.
Measure: Auto or fixed range. Fixed range selection made by choice of
COMPLIANCE value.
FILTER: Takes n measurements, calculates and outputs average (n = 2,4,
8,16, or 32, selectable).
SUPPRESS: Subtracts displayed measurement from subsequent readings.
MENU: DC Measurement Delay, Default Delay On/Off, Local/Remote
Sense, 50/6OHz, IEEE Address, Self Tests.
DATA ENTRY: Numeric keypad or detented rotary dial.
TRIGGER:
Input and Output: Set for any phrise of SOURCE-DELAY-MEASURE
sequence or trigger output at end of sweep.
Origin: Internal, External (including front panel MANUAL TRIGGER
button), IEEE-488 bus (TALK, GET, “X9.
MEMORY: Stores one full sweep (up to 1000 points) of source, delay, and
measure values, elapsed times, and sweep parameters. Lithium battery
backup.
INTERLOCK: Use with test fixture or external switch. Normally closed;
open puts instrument in standby.
267 ts::: (60 Hz)
20.00 msec. (50 Hz)
Delay
Measure
Integration Tie
4-digit resolution
Sdigit resolution
Sdigit resolution
VOLTAGE
SOURCE V
RANGE ACCURACY
(Max.
Value) SIZE 18=-WC)
f1.5000V 100 FV *(0X133% + 8OOpV 100 PV 10 PV f(O.OZS% + 4501’.
f15.000V 1mV *(0.033%+ 2.7mV)
f110.00V 1OmV f(0.033%+ 24mV)
I, = Oulput current
I, = Full scale on selected current range
I Spe&cations apply for 5digit resolution. For 4-d@ resolution add 1OOppm of
range. Assumes remote sense for I > lOOpA.
2 On the 1A range use [1,&l x 25OpV.
COMPLIANCE: Bipolar current limit set with single value.
Maximum: flA WOOmA on the 1lOV range).
STEP (1 Year,
+ [1,/I,] x 600~V)z
Minimum: fl% of selected voltage range.
Accuracy, Step Size: Same as current source.
NOISE (p-p typical):
Range
110 v < 3ppm of range
15 v
1.5v
WIDEBAND NOISE: 0.1 to 2OMHz,8mV p-p typical.
OVERSHOOT: ~0.01% (IlOV step, 1OmA range).
SETTLING TIME: <5OOpsec. to 0.01% (1lOV step, 1OmA range).
NMRR: >60dB at 50 or 6OHz (LINE CYCLE integration time selected).
CMRRz>120dBatDC,50or60Hz (LINECYCLE integration timeselected).
INPUT IMPEDANCE (as a voltmeter): >lOW paralleled by <20pF.
< 3ppm of range
<lOppm of range
MEASURE V
ACCURACY’
RESOLUTION
4-Diait S-Diait
1mV 100 PV f(0.025%+ 13mV)
1OmV
O.l-1oHz
1mV f(0.025%+ 1OmV)
(1 Year,
w-28°C)
+ ~I,/I,l x 6cQw
CURRENT
SOURCE I
RANGE ACCURACY ACCURACW
(Max.
Value) SIZE
f1.0000 nA 100 fA k(O.3 %+ 450 fA) 100 f.4 10 IA f(0.3 %+ 100 fAy
*10.000 nA 1 pA f(03 %+ 2 pAI 1 pA 100 fA &CO3 %+ 1 pA)
fllM.00 nA 10 pA f(O.Zl%+ 20 pA) 1OpA
f1.0000 fl 100 pA f(0.05%+ 200 PA) 100 pA 10 pA f(0.04 %+ 60 pAI
*10.000 /lA 1 nA xk(0.05%+ 2 nA) 1 nA 100 pA f(0.035%+700 pA)
floO.OO pA 10 IL4 +(0.05%+ 2OnA) 1onA
fl.OOOOmA 100 XL4 +(o.a5%+ 200 nA) 100 nA 10 nA f(0.035%+ 60 nA)
+1o.OOomA 1 @ *(0.05%+ 2 @, 1 fl loOnA f(0.038%+600 nA)
*1oO.oomA 10 fl *co.1 %+ 20 @A) lOti 1 @ HO.1 %+ 6 +A)
f1.0900 A 100 pA f(0.12%+ 700 @A) lOO@ 1OM f(0.12 %+3CKJ @A)
‘Speciilcations apply for 5-d@ resolution. For 4-digit resolution, alI offset terms
are 2OOppm of range.
20ffset spedfication applies for 23°C i 1°C with suppression. Temperature
coefficient SOfA/“C.
STEP
(1 Year,
W-2800
4-D&$ S-Digit
MEASURE I
RESOLUTION
1 pA f(0.21 %+ 6pA)
1 nA f(0.035%+ 6nAf
(1 Year,
18”-28°C)
Specifications subject to change without notice.
COMPLIANCE: Bipolar voltage limit set with single value.
Maximum: fllOV (*15V on the 1A range).
Minimum: fl% of selected current range.
Accuracy, Step Size: Same as voltage source.
NOISE (p-p of range): O.l-1OHz <3pim (<20ppm on InA, 10~4 and IA
ranges).
OVERSHOOT: ~0.01% typical (lOmA step, R, = 1OkQ).
SETTLING TIME: <500psec. to 0.01% (lOmA step, R, = 1OkQ).
OUTPUT R, C: >lOW paralleled by <20pF (on 1nA range).
IEEE-488 BUS IMPLEMENTATION
MUCTILINE COMMANDS: DCL, LLO, SDC, GET, GTL, UNT, UNL, SI’E,
SPD.
UNILINE COMMANDS: IFC, REN, EOI, SRQ, ATN.
INTERFACE FUNCTIONS: SHI, AI-II, T6, TEO, L4, LEO, SRI, RLI, PPO,
DCI, DTI, CO, El.
All front panel functions and setups are available over the IEEE-488 bus, in
addition to Status, Service Request, Output Format, EOI, Trigger, and
Terminator.
IEEE-488 address is set from front panel menu.
EXECUTION SPEED
MINIMUM SOURCE-DELAY-MEASURE CYCLE TIME: lmsec.
RESPONSE TO IEEE-488 COMMAND (as a source): 25msec.
MEASUREMENT RATE: lmsec. per point into internal buffer.
CONTINUOUS MEASUREMENT SPEED (source DC value over IEEE-
488 bus): 110 readings per second.
TRIGGER LATENCY TIME: c2msec.
GENERAL
LOAD CAPACITANCE: Stable into 20,OOOpF typical.
REMOTE SENSE: Corrects for up to 2V drop in each output lead. Maxi-
mum lw2 per sense lead for rated accuracy. Residual output resistance
(as a voltage source) is 0.5R.
GUARD: Output Resistance: 512kQ.
Maximum Output Current: f2mA.
Open Circuit Offset Relative to Output HI: XZ.mV max.
ISOLATION (Output LO to chassis): Typically >lOk’R in parallel with
650pF.
MAXIMUM COMMON MODE VOLTAGE: 200V peak.
CONNECTORS: Outputs: 3-lug triax.
Trigger Input/Output: BNC.
Interloclo 3-pin miniature DIN.
TEMPERATURE COEFFICIENT to’-lS’=C & 28=5O“Cl:
f(O.l x applicable accuracy specification)/“C.
ENVIRONMENT:
Operating: O”-5O”C, 70% relative humidity up to 35°C. Linearly derate
3% RH/T, 35=50°c.
Storage: -25’ to 65°C.
WARM-W: One hour to rated accuracy.
COOLING: Internal fan forced air cooling.
POWER: 105-125 or 210-250V AC (external switch selectable), 90- 1lOV
and 180-220V version available. 120VA max.
DIMENSIONS, WEIGHT: 89mm high x435mm wide x 448mm deep (3!4
in. x 17% in. x 1% in.). Net weight 9kg (19.75 lbs.).
ACCESSORIES SUPPLIED:
Model 7078-m-10: Triax to Triax Cable, 3m (10 ft.1 (2 supplied)
Model 236ILC-3: Interlock Cable
ACCESSORIES AVAILABLE:
Model 8000-10: Equipment Rack for 3 SMUs (10 in.1
Model 8000-14: Equipment Rack for 4 SMUs (14 in.1
Table of Contents
SECTION 1
1.1
1.2
1.3
1.4
1.5
1.5.1
1.5.2
1.5.3
1.5.4
1.5.5
1.5.6
1.5.7
1.5.8
1.5.9
- Performance Verification
INTRODUCTION
ENVIRONMENTAL CONDITIONS
INITIALCONDITIONS .........................................................
REQUIREDTESTEQUIPMENT ...................................................
VERIFICATION PROCEDURES
Equipment Characterization
CommonModeVerification
Voltage Source Verification
VoltageMeasureVerification
RemoteSenseVerification ......................................................
Low Current (1nA to lOmA) Measure Ranges Verification
Low Current (1nA to lOmA) Source Ranges Verification
lOOmA and 1A Measure Ranges Verification
lOOmA and 1A Source Ranges Verification
..............................................................
SECTION 2 - Calibration
2.1
2.2
2.3
2.4
2.5
2.6
2.6.1
2.6.2
2.6.3
2.6.4
2.7
2.8
LNTRODUCTION
RECOMMENDED CALIBRATION EQUIPMENT
ENVIRONMENTAL CONDITIONS
WARM-UPPERIOD
CALLOCK
CALIBRATION PROCEDURES
Equipment Characterization
Voltagecalibration
lOOmA and 1A Ranges Calibration
Low Current Ranges Calibration (1nA - lOmA)
CALIBRATION ERRORS
CALIBRATION PROGRAM
..............................................................
....................................................................
................................................
...................................................
....................................................
..................................................... l-6
.....................................................
.................................................... l-8
..............................
................................
........................................
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...................................................
....................................................
........................................................... 2-5
................................................
......................................
........................................................
......................................................
l-l
1-l
l-l
l-l
l-l
l-3
l-7
l-10
l-11
1-13
1-16
1-16
2-l
2-l
2-1
2-l
2-2
2-2
2-2
2-8
2-11
2-13
2-14
SECTION 3 - Maintenance
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.8.1
INTRODUCTION..
LINEFUSEREPLACEMENT .....................................................
FANFlLTERCLEANING
BAl-I’ERY REPLACEMENT
HANDLING AND CLEANING PRECAUTIONS
DISASSEMBLY INSTRUCTIONS
SPECIAL HANDLING OF STATIC SENSITIVE DEVICES
TROUBLESHOOTING
Recommended Test Equipment
............................................................ 3-l
3-l
........................................................
......................................................
......................................
..................................................
................................
.......................................................... 3-8
..................................................
3-l
3-2
3-2
3-4
3-8
3-8
3.8.2
3.8.3 Power Supply Checks
3.8.4 Analog Control Lines
3.8.5 AnalogSwitching
3.8.6 Digital and Display Checks
Diagnostics
.................................................................
.........................................................
..........................................................
............................................................
.....................................................
3-8
3-10
3-10
3-11
3-12
SECTION 4
4.1
4.2
4.2.1
4.2.2
4.2.3
4.3
4.4
4.4.1
4.4.2
4.4.3
4.4.4
4.5
- Principles of Operation
INTRODUCTION
ANALOGCIRCUrrRY
V/IControlandReadback
OutputModule
V/IFeedback
A/DCONVERTER
DIGITALCIRCUITRY
I/OController
Souce/MeasureController
Communications
DisplayCircuitry
POWERSUI?PLY ..............................................................
..............................................................
..........................................................
......................................................
..............................................................
...............................................................
............................................................. 4-8
..........................................................
...............................................................
.............................................................
.............................................................
SECTION 5 - Replaceable Parts
5.1 INTRODUCTION
5.2
5.3 ORDERING INFORMATION
5.4 FACTORYSERVICE
5.5
PARTSLISTS .................................................................
SCHEMATIC DIAGRAMS AND COMPONENT LOCATION DRAWINGS ...................
..............................................................
............................................................
.....................................................
.....................................................
4-l
4-2
4-2
44
4-5
4-8
4-8
49
49
4-9
4-10
5-l
5-l
5-l
5-l
5-l
List of Illustrations
SECTION 1
Figure l-l Setup for Equipment Characterization
Figure l-2 Setup for Common Mode Verification
Figure l-3 Setup for Voltage Source Ranges Verification
Figure l-4 Setup for Voltage Measure Ranges Verification
Figure l-5
Figure l-6
Figure l-7
Figure l-8 Setup for lOOmA and 1A Measure Ranges Verification
Figure l-9 Setup for lOOmA and 1A Source Ranges Verification
- Performance Verification
....................................
....................................
..............................
.............................
Setup for Remote Sense Verification
Setup for Low Current Measure Ranges Verification (1nA to lOmA)
Setup for Low Current Source Ranges Verification (1nA to lOmA)
.....................................
SECTION 2 - Calibration
Figure 2-1 Calibration Switch (Cal Lock)
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5
Figure 2-6
Figure 2-7
Setup for Equipment Characterization
Setup for VoltsCalibration
Setup for lOOmA and 1A Ranges Calibration
Current Ranges Calibration (1nA to lOmA)
Ul Error Status Word
U7 Calibration Status Word
...................................................... 2-14
................................................ 2-2
.......................................... 2-3
.................................................. 2-6
..................................... 2-9
..................................... 2-11
................................................. 2-14
.......................
.........................
.............
...............
. . . l-5
. . .
l-6
. . . l-7
. . . l-9
. . . l-10
. . .
1-12
. . . 1-15
. . . 1-17
. . .
1-18
SECTION 3 - Maintenance
Figure 3-l
Figure 3-2.
Figure 3-3.
Figure 3-4.
Figure 3-5
Line Voltage Switch and Line Fuse
DigitalBoard
OutputBoard..
Analog Board (Shields Removed)
Model 238 Exploded View
............................................................
..........................................................
..................................................
SECTION 4 - Principles of Operation
Figure 4-l.
Figure 4-2.
Figure 4-3.
Figure 4-4.
Figure 4-5. Damping Relay Contact Bounce
OveraIIBlockDiagram
Simplified Schematic of V/I Control and Readback
Output Module (Simplified Schematic Diagram)
V/I Feedback (Simplified Schematic)
...............................................
............................................ 3-l
.............................................
. . . 4-l
..........................
............................
....................................
........................................
. . . 4-2
. . . 4-5
. . . 4-6
. . . 4-7
3-3
3-5
3-6
3-7
List of Tables
SECTION 1
Table l-l
Table l-2
Table l-3
Table l-4
Table l-5
Table l-6
Table l-7
Table 1-8
Table l-9
- Performance Verification
Required Test Equipment
Specifications for Alternate Equipment
Model 263 I-Source Characterization ................................................
VoltageSourceVerification
VoltageMeasureVerification
Allowable Reading Calculations for Low Current Measure Verification (1vA to lOmA).
Low Current Measure Verification (1nA to lOmA) .....................................
Allowable Reading Calculations for Low Current Source Verification (lnA to lOmA)
Low Current Source Verification (1nA to lOmA) .......................................
SECTION 2 - Calibration
Table 2-l
Table 2-2
Table 2-3
Table 2-4
RequiredTestEquipment
Specifications for Alternate Equipment ..............................................
Model 263 I-Source Characterization ................................................
Calibration Error Messages ........................................................
SECTION 3 - Maintenance
Table 3-l
Table 3-2
Table 3-3
Table 3-4
Table 3-5
Table 3-6
Table 3-7
Table 3-8
Table 3-9
Table 3-10
LineFuseSelection
Recommended Troubleshooting Equipment
FowerSupplyChecks
Analog Switching; Current Ranging
Analog Switching; Current Ranging
Analog Switching; Feedback
Analog Switching; Sensing
Analog Switching; A/D Multiplexing
DigitalCircuitryChecks
DisplayCircuitryChecks
..........................................................
..............................................
.........................................................
.......................................................
.....
.......
..........................................................
...............................................................
..........................................
............................................................. 3-10
................................................
................................................
.......................................................
.........................................................
...............................................
...........................................................
..........................................................
l-2
l-3
14
l-8
l-9
l-11
1-12
1-13
1-14
2-l
2-2
2-5
2-13
3-1
3-8
3-11
3-11
3-12
3-12
3-12
3-13
3-14
SECTION 4 - Principles of Operation
Table 4-l
VoltsRangeRelays
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-8
+
SECTION 1
Performance Verification
1.1 INTRODUCTION
The procedures outlined in this section may be used to
verify that the instrument is operating within the limits
stated in the specifications at the front of this manual.
Performance verification may be performed when the instrument is first received to ensure that no damage or
n&adjustment has occurred during shipment. Verification may also be performed whenever there is question of
instrument accuracy, or following calibration, if desired.
NOTE
If the instrument is still under warranty (less
than 1 year from the date of shipment), and its
performance falls outside the specified range,
contact your Keithley representative or the
factory to determine the correct course of action.
Before attempting any of the following procedures, make
sure you are familiar with the controls and operation of
the Model 238. Refer to the Model 238 Operator’s Manual
for complete information.
1.3 INITIAL CONDITIONS
WARNING
The Source Measure Unit is equipped with a
3-wire power cord that contains a separate
ground wire and is designed to be used with
grounded outlets. When proper connections
are made, instrument chassis is connected to
power line ground. Failure to use a grounded
outlet may result in injury or death due to
electric shock.
The Model 238 must be turned on and allowed to warm
up for at least one hour before beginning the verification
procedures. If the instrument has been subject to extremes of temperature (outside the range specified in
paragraph 1.2), additional time should be allowed for internal temperatures to reach normal operating temperature. Typically, it takes one additional hour to stabilize a
unit that is 10°C (18°F) outside the specified temperature
range.
1.4 REQUIRED TEST EQUIPMENT
Table l-l lists all the test equipment required for verification. The procedures for performance verification are
based on using this exact equipment.
WARNING
The procedures in this section are for use
only by qualified service personnel. Do not
perform these procedures unless qualified
to do so. Many of these steps in this section
may expose you to potentially lethal voltages that could result in personal injury or
death if normal safety precautions are not
observed.
1.2 ENVIRONMENTAL CONDITIONS
All measurements should be made at 18-2B°C (65432°F)
and at less than 70% humidity.
Alternate equipment may be used as long as the substitute equipment has specifications at least as good as
those listed in Table 1-2. Note that equipment characterization (paragraph 1.5.1) is not required if using equipment that meets the specifications in Table 1-2.
1.5 VERIFICATION PROCEDURES
The following paragraphs contain the detailed procedures for verifying the one year accuracy specifications of
the Model 238 using the equipment listed in Table l-l.
NOTE
The allowable reading limits in these procedures only reflect the specifications of the
Model 238. They do not include error contributed by test equipment.
+
l-l
SECTION 1
Performance Verification
+
These procedures are intended for use only by qualified
personnel using accurate and reliable test equipment. If
the instrument is out of specifications and not under warranty, refer to the calibration section of this manual.
WARNING
Lethal voltages (up to 1OOV) will be connetted to the Model 8006 test fixture. To
avoid a possible shock hazard, the safety in- nals of the Model 238.
terlock circuit must be connected to the
Model 238.
Connect the test fixture screw to safety earth
ground using #18 AWG wire minimum before use. Turn off all power before connecting or disconnecting wires or cables.
Also, keep in mind that GUARD is always
enabled. Thus, a lethal voltage on OUTPUT
HI is also present on the two GUARD termi-
Table l-l Required Test Equipment
Manufacturer
Keithley
Keithley 193A 5-l /2 digit DMM
Keithley
Model
263
617
Description
5-l/2 digit Calibrator/
Source
41/2 digit
Electrometer
Specifications
2nA,2OnA ranges; +(0.0625% + 10 counts)
2OOnA range; &(0.035% + 10 counts)
2OOmV, 2V ranges; +(0.005% + 2 counts)
2OV-1OOOV ranges; +(0.007% + 1 count)
2OOR-200WZ ranges; +(0.007% + 2 counts)
200@-2mA ranges; &(0.09% + 10 counts)
2pA range; +(1.6% + 66 counts)
20 A range; ~-0.6% + 7 counts)
2 obl pA range; k&6% + 1 count)
2nA range; +(0.25% + 5 counts)
2OnA range; +(0.25% + 1 count)
2001~4 range; &(0.25% + 1 count)
2fi range; +(0.15% + 4 counts)
2OpA range; &(0.15% + 1 count)
Keithley
Keithley
Fluke
Valhalla
Keithley
Keithley
Keithley
Pomona
1-2
8006
236-TLC-3
343A
2500E
R-249-100
R-263-l k
R-263-100K
7078-TRX
6172 2-slot male to 3-lug
B-24
Test Fixture
Interlock Cable
DC Voltage Calibrator
Current Calibrator
1OOQ Resistor
1161 Resistor
1OOkQ Resistor
3-slot triax cable
(3 required)
female triax adapter
(2 required)
Banana plug cable
(6 required)
-
-
lOV-1OOV ranges; +0.002%
lOOmA-1A ranges; +0.025%
+O.l%, &20ppm/“C
+O.l%, +lOppm/“C
+O.l%, +lOppm/“C
-
-
-
+
+
Performance Verification
SECTION 1
Table 1-2 Specifications for Alternate
Equipment
Instrument Type
DMM
Source DC Current
Measure DC Current 250ppm rdg +5OOnA
1 s.1
In order to verify the I@, lo@, lOOl.tA, 1mA and 1Om.A
source and measure ranges of the Model 238, the 0.9p.A,
9p.A, 9Ol.& 0.9mA and 9mA outputs of the Model 263 are
characterized.
1. Connect the Model 263 source, Model 193A DMM
2. Configure the source and DMM as follows:
3. Zero the Model 193A as follows:
A. At the SENSE 1 (HI) terminal of the test socket,
C. On the Model 193A, enable ZERO to cancel test
D. Relocate the jumper back to the SENSE 1 termi-
4. In the space provided below, use a pencil to record
the actual value of the 100&J resistor from the display of the Model 193A.
Equipment Characterization
and Model 8006 test fixture as shown in Figure l-l.
Install the 1OOwZ resistor (in Table l-1) in the AXIAL
KELVIN CLIPS test socket of the test fixture.
Model 263 - Amps function, +0.9OOOOfl on 2lrA
range, GUARD enabled and output in standby.
Model 193A - Ohms function on the 2OOkQ range,
disconnect the jumper whose other end is connected to BINDING POST 2 on the Signal Panel.
B. Connect that jumper to the SENSE 2 (LO) termi-
nal of the test socket. This shorts the Ohms Sense
input of the Model 193A at the test socket.
lead resistance.
nal of the test socket. Make sure the connections
at the Component Test Module are correct as
shown in Figure l-l.
R
look0 =
Required Specifications
Same as Keithley 193A
(see Table l-l)
0.9nA, 9nA, 9OnA, Same as
Keithley 263 (see Table l-l)
0.9@; +lBOppm
9pA, 90/.&A, 9oopA, 9mA;
fl70ppm
9OmA; k230ppm
0.9A; f625ppm
lcQ
5. Set the Model 193A to the DCV function and the
200mV range, and disable zero.
6. To cancel any offset, zero the Model 193A by shorting its input (VOLTS HI to LO) and enabling zero.
7. Remove the short from the input of the Model 193A
and place the Model 263 in operate to source
+0.9OOOOl.tA to the 1OOkQ resistor
8. In the space below, use a pencil to record the voltage
drop across the resistor from the display of the
Model 193A.
V100m =
9. Calculate (to 5-l/2 digits) the current through the
100162 resistor as follows:
Io.sfl = - = @
Io.9~ is the characterized current for the 2@ range of
the Model 263. It is used to check the $A measurement range of the Model 238. Using a pencil, record
the calculated value of Io.s,,A in Entry 1 of Table l-3.
10. Place the Model 263 in standby.
11. Set the Model 193A to the 2V range.
12. Set the Model 263 to source 9.OOOOfl on the 2OpA
range and enable operate.
13. As performed in steps 8 and 9, measure the voltage
across the 1OOm resistor and calculate the current.
V
lWk0 =
Iqi~=-= PA
I9@ is the characterized current for the 2Olt.A range of
the Model 263. It is used to check the IO@ measurement range of the Model 238. Using a pencil, record
the calculated value of IgM in Entry 2 of Table l-3.
14. Place the Model 263 in standby.
15. In the test fixture, remove the 1OOkQ resistor and in-
stall the lkrcz resistor (R-263-lk).
16. On the Model 193A, select the Ohms function, 2kQ
range and disable zero.
17. Repeat step 3 to zero the Model 193A.
18. Measure and record the value of the 1wZ resistor.
RW =
19. Set the Model 193A to DCV and the 200mV range,
and disable zero.
20. To cancel any offset, zero the Model 193A by shorting its input (VOLTS HI to LO) and enabling zero.
21. Remove the short from the input of the Model 193A
and set the Model 263 to source 90.000pA on the
2OOlrA range and enable operate.
v100kn
RlC0kn
V100m
RlOOkn
mV
V
kR
+
1-3
SECTION 2
Performance Verification
+
22. Record the voltage measurement from the Model
193A and calculate the current.
vMl=
go@=-=
I
Vlkn
mV
cw-\
Rlkn
190,~ is the characterized current for the 2OO@ range
of the Model 263. It is used to check the lOOpA measurement range of the Model 238. Using a pencil, record the calculated value of 190~ in Entry 3 of
Table l-3.
23. Place the Model 263 in standby.
24. Set the Model 193A to the 2V range.
25. Set the Model 263 to source 0.9OOOOmA on the 2mA
range, and enable operate.
26. Record the voltage measurement from the Model
193A and calculate the current.
v1ko=
V
VlCWl
IO.WA = - =
RIO09
10.~ is the characterized current for the 2rruA range
of the Model 263. It is used to check the 1mA measurement range of the Model 238. Using a pencil, record the calculated value of Io.hn~ in Entry 4 of
Table l-3.
27. Place the Model 263 in standby.
28. In the test fixture, remove the 1kQ resistor and install
the 1OOQ resistor (R-249-100).
29. On the Model 193A, select the Ohms function, 200R
range and disable zero.
30. Repeat step 3 to zero the Model 193A.
31. Measure and record the value of the 1OOR resistor.
Rloon =
sz
32. Set the Model 193A to DCV and the 2V range, and
disable zero.
33. To cancel any offset, zero the Model 193A by shorting its input (VOLTS HI to LO) and enabling zero.
34. Remove the short from the input of the Model 193A
and set the Model 263 to source 9.OOOOmA on the
20mA range and enable operate.
35. Record the voltage measurement from the Model
193A and calculate the current.
V
loon =
rz
VW09
1-c-z
R1KX-J
IB,,A is the characterized current for the 2OmA range
of the Model 263. It is used to check the 1OmA measurement range of the Model 238. Using a pencil, record the calculated value of IsmA in Entry 5 of
Table l-3.
36. Place the Model 263 in standby.
Table 1-3 Model 263 I-Source Characterization
263 I-Source
Programmed
Entry
1
2
3
Range
2P4
2oP4
2ooJ.A
4
5
Ihe~aracterizedI-sourcevvaluesshouldbewithinthelistedlimik.Theselimikarebssedon90-&yspedficationsof theMcdelsZ63
and 193kAcharacterizedvaluethatdoesnot fallwithintheselimikindicatesacalculationerror,orthat theModel263and/orModel
193A is out of specification.
2omA
Value
0.9OOOOltA
9.oooopA
9o.ooopA
0.90000mA
9.oooomA
Characterized
I-Source Value Value Limits*
10.9pA =
Isp~ =
19qlA =
10.9mA =
Igm.4 = 9rfd +5.4pA
I-Source
0.9p.A +450pA
9pA k4.3n.A
9OpA +45nA
0.9mA *43onA
l-4
+
+
SECTION 2
Performance Verification
Banana Plug Cables (5)
z
8
Warning: Connect
to Safety Earth
Ground
A. Connections
Signal
PalMI
Component
Test
Module
Source
(Source I)
_-- -.. -m--a.
-. -* -.
Model 8006 Test Fixture
263
COMMON
707&TRX--
Cable
_.“.
-I
Model 193A DMM
i-l volts
193A DMM
(Measure Q and V)
8. Schematic Equivalent
Figure l-1 Setup for Equipment Characterization
1-5
SECTION 1
Performance Verification
+
1.5.2 Common Mode Verification
Set up the equipment as shown in Figure l-2 and perform
the following steps for common mode verification.
1. While in standby, program the Model 238 as follows;
j TIME at LINECYCLE PERIOD, source at
+l.OOOOuA, and compliance at 1V on the 1.5V range.
Interlock Cable (236~ILC-3)
2. Place the Model 238 in OPERATE and, using a pencil, record the voltage measurement in the space provided below.
V
+1pA =
V
3. From the keypad, change the source value to
-1.OOOOl.tA and record that measurement.
V-l&A =
V
4. Subtract the two voltage measurements from each
other Verify that the absolute value of the result is
_ --* __
<l.ZUmV
I v+1fl- V-IU I <1.20mV
Warning: Connect
to Safety Earth
Ground
Figure 1-2
8006 Test Fixture
A. Connections
238
(Source I, Measure V)
B. Schematic Equivalent
Setup for Common Mode Verification
J
Shorted Output
1-6
+
+
SECTION 1
Performance Verification
1.5.3
Voltage Source Verification
Set up the equipment as shown in Figure l-3 and perform
the following steps to verify the voltage source.
WARNING
The following procedure uses hazardous
voltages (1OOV) that could cause injury or
death. Exercise extreme caution when encountering these lethal voltage levels.
1. Set the Model 193A to measure DCV on the 200mV
range.
2. While in standby, set the Model 238 to source OV on
the 1.5V range and set compliance to lOmA.
3. Temporarily disconnect the banana cable from
BINDING POST 2 at the rear panel of the test fixture
and connect it to VOLTS LO of the Model 193A. This
will short the input of the Model 193A DMM.
Interlock Cable (236~ILC-3)
I
]
4. On the Model 193A, press ZERO to cancel any measurement offsets.
5. Reconnect the banana cable to BINDING POST 2 of
the test fixture.
6. Place the Model 238 in operate and verify that the
reading on the DMM is within the limits shown in
the first entry of Table 1-4. Use the filter if the reading is noisy.
7. Press the SELECT 4 button to select the 15V range
and verify that the DMM reading is within the allowable limits in Table l-4.
8. Using Table l-4 as a guide, repeat step 7 to check the
OV output on the 11OV range.
9. From the keypad, program the Model 238 to source
+lV on the 1.5V range and verify that reading on the
193A DMM is within the allowable limits.
10. Repeat step 9 for a source value of -lV.
11. Using Table 1-4 as a guide, check source values of
+lOV and +lOOV.
12. Program the Model 238 to OV and place it in standby.
I
238
Figure 1-3
8006 Test Fixture
A. Connections
OUTPUTHI @
238
(Source v) OUTPUT LO
B. Schematic Equivalent
Setup for Voltage Source Ranges Verification
I
193A DMM
Banana Plug
Cables (2)
l HI
a Lo (Measure V)
+
193A DMM
1-7
343A Range
+
Table l-5 Voltage Measure Verification
238
Compliance Limit
343A Output & Measuring Range*
SECTION 1
Performance Verification
Allowable Reading
mYT to 2PC)
1ov
1ov
1ov
1ov
ov 1.5v -0.00045v to +0.00045v
ov
ov
+lV
1ov -lv
1ov +lOV
1ov
-lov 15v -9.9962V to -10.0038V
1oov +lOOV
1oov -loov
15v
1lOV
-00.0013v to +00.0013v
-000.010v to +ooo.o1ov
1.5v +0.99927V to +l.O0073V
1.5v -0.99927V to -1.00073V
15v +9.9962V to +lO.O038V
1lOV +99.965V to +lOO.O35V
11ov -99.965V to -100.035v
Interlock Cable (236~ILC-3)
238
I
Figure Z-4
800
16 Test Fixture
A. Connections
343A
DC Calibrator
+@
oUTPUT _ l
(Source V)
B. Schematic Equivalent
Setup for Voltage Measure Ranges Verification
I I
+
- .-..
DC Calibrator
@ OUTPUTHI
OUTPUT Lo
J VJ
238
(Measure V)
l-9
SECTION 1
Performance Verification
+
1.5.5 Remote Sense Verification
Set up the equipment as shown in Figure 1-5. The 1kQ resistor (R-263-l k) is installed in the Kelvin test socket. Per-
form the following steps to verify remote sense accuracy:
WARNING
When a Model 238 is programmed for re-
mote sensing, hazardous voltage may be pre-
sent on the SENSE and OUTPUT terminals
when the unit is in operate regardless of the
programmed voltage or current. To avoid a
possible shock hazard, always turn off all
power before connecting or disconnecting
cables to the Source Measure Unit or the associated test fixture.
interlock Cable (236-ILC-3)
1. While in standby, place the Model 238 in remote
sense and set it to source 1OV with a compliance limit
of 1OmA on the 1OmA measurement range. Place the
Model 238 in standby.
2. Set the Model 193A DMM to DCV and select the 20V
range.
3. TeGporarily disconnect the banana cable from
VOLTS HI of the DMM at the rear panel of the test
fixture (BINDING POST 11, and connect it to VOLTS
LO of the DMM. This shorts the input of the Model
193A DMM.
4. On the Model 193A DMM, enable zero to cancel any
offsets.
5. Re-connect the banana cable to BINDING POST 1 of
the test fixture.
6. Place the Model 238 in operate and verify that the
reading on the DMM is within the following allowable l 9.994OV to 10.006OV.
7. Place the Model 238 in standby and local sense.
Figure 1-5
l-10
o?
01
.a 81 IQ
B
o?
ci?“?
Q, ,8
gs 8
6
8006 Test Fixture
A. Connections
8. Schematic Equivalent
Setup for Remote Sense Verification
\
7076-TRX
Cables (3)
+
+
Performance Verification
SECTION 1
1.5.6
Low Current (1 nA to 1 OmA)
Measure Ranges Verification
Set up the equipment as shown in Figure l-6 and perform
the following steps to verify the 1nA to 1OmA measure
ranges:
1. Use Table 1-6 to calculate the allowable readings for
the 1rnA through 1OmA ranges. The values for Io.~,
IPM, Igofi, Io.gmA and IhA were previously calculated
and recorded in Table l-3. After calculating these
readings, transfer them to Table l-7.
2. While in standby, configure the Model 238 to measure current by setting it to source OV on the 1.5V
source range.
3. While in standby, set the Model 263 to the 2nA range
and enable guard.
4. Set the compliance limit of the Model 238 to 1nA on
the InA measurement range and enable operate.
Verify that the current measurement on the Model
238 is within the allowable limits listed in the first entry of Table l-7.
5. On the Model 238, change the compliance limit to
1OnA on the 101~4 measurement range. Verify that
the reading on this measurement range is within the
limits specified in the table.
6. Using Table l-7, check the rest of the Model 238 current ranges with the output of the Model 263 in
standby.
7. Set the Model 263 to output +0.9OOOOnA on the 2nA
range, and set the Model 238 compliance limit to 1nA
on the 11~4 measurement range.
8. Verify that the reading is within the limits specified
in the table.
9. On the Model 263, change the output to negative polarity and verify that the reading is within the limits
specified in the table.
10. Using Table l-7 as a guide, check the 1OnA through
1OmA measurement ranges of the Model 238.
11. Place the Model 263 in standby.
Table 1-6 Allowable Reading Calculations for Low Current Measure Verification (1pA to 10mA)
238
Measure
Range Reading Calculations*
w
101.t.A
100/.~A
In-IA +Io.g,,,~ + [ (0.00035) Io.g,,,~ + 60nA ] =
lOIlL +Igti + [ (0.00038) &A + 6001~4 I=
T.- T- T*. T.. --AK
*
l”.Ypl, rw, ‘rym, Lwlr,,4, QI,U lgmA cue ““lii”llxl Ir”In I aole I-J
**
Allowable reading limits are to be transferred to Table 1-7.
***
The calculated allowable readings should be within listed typical limits. These limits are based on the 90day specifications of the
Model 263 and 193A. A calculated allowable reading that does not fall within these limits indicates a calculation error, or that the
Model 263 and/or Model 193A is out of specification.
+Io.glrA~[(0.0004)Io.g1rA+60pAl=
-Io.g,ue+~O.00O4)Io.gru\+6OpAl= -m.------ M --.----- PA
+1~~+[(0.00035)1~~+700pA1= + _._____ I.IA
-I~CIA+[(0.00035)Ig~+700pAl=
+Igo@ f. [ (0.00035s> Igo@ + 6nA 1 =
-IgoltA + I: (0.00035> IN,,A + 6nA I=
-Io.sm~+ [ (0.00035) IO.- + 6OnA ] =
-1gmA + [ (0.00038) LA + 6OOnA I=
^-^ -I-r-:--2 L--- ‘F-L-- - -
+ _._____ PA
- _._____ PA
+::I_:: @
+- . _ _ _ _ _ mA
--. _ _____ mA
+- . _ _ _ - mA
-- . ___I mA
Allowable Reading**
Lower Limit
ti +
Typical
Upper Limit Limits***
+ _._____ PA
+-.-s-m- CIA
- _.____ PA
PA
--:::::: /.LA
+- . _ _ _ _ _ mA
--. _ ____ mA
:::::I: 2
+0.9OOOOpA +870pA
-0.90000~ +870pA
+9.OOOOp.A +8nA
-9.OOOOpA &8nA
+9O.OOOpA ~831.~4
-9O.OOOp4 +83nA
+0.9OOOOmA +8OOnA
-0.90000mA~800nA
+9.0000d +9.4pA
-9.OOOOmA &9.4pA
l-11
SECTION 1
Performance Verijcation
Figure l-6.
Grdund Link
Note : 263 GUARD enabled
Banana Plug C&la
263 Source
(Source I)
6172 2-Slot to 3-Lug
Female Tr&x adapter
7076-TRX
Cable
238 (Measure I)
Setup for Low Current Measure Ranges Vkrijication (InA to ZOmA)
Table 1-7 Low Current Measure Verification (InA to 10mA)
238
263
Range
263 Output & Measure Range*
2nA Standby
Compliance Limit
1lIA
Allowable Readings**
(18OC to 28OC)
-0.00010nA to +0.00010nA
Standby lOIL4 -00.0010nA to +00.0010nA
2nA Standby 1OOllA -000.006nA to +OOO.O06nA
2nA Standby
2nA
Standby 10pA
Standby
2nA
Standby ImA
2nA Standby
UA
lOOpA
1OmA
-0.00006pA to +O.O0006pA
-00.0007pA to +OO.O007pA
-000.006pA to +ooo.O06~A
-0.00006mA to +O.O0006mA
-00.0006mA to +OO.O006mA
2nA +0.9000onA II-IA -0.8972OnA to -0.9028OnA
2nA -0.90000nA
2onA
+9.oooonA
h-IA
l&IA
+0.8972OnA to +0.9028OnA
-8.972OnA to -9.028OnA
2onA -9.oooonA lOIL4 +8.972OnA to +9.028OnA
2oOnA +9o.ooonA
2oOnA
&A
&A
-9o.ooonA lOonA
+0.90000pA
-0.90000pA
20vA +9.OOOOpA
20pA -9.OOOOpA
200pA
200pA
+90.000pA
-9O.OOOpA lOOpA
2mA +0.90000mA
2mA
20mA
-0.90000mA 1mA
+9.0000mA 1OmA
20mA -9.oooomA lOmA
*238 set to source OV on the 1.5V source range.
**Allowable readings for the 1pA through 1OmA ranges are calculated in Table l-6.
lOonA
UA
&A
10pA
10pA
lOOpA
1mA
-89.805nA to -90.195nA
+89.805nA to +90.195nA
to -
+
to +
to -
+
to +
to -
+
to +
to -
+
to +
to -
+
to +
1-12
+
Performance Verification
SECTION 2
1.5.7
Low Current (1 nA to IOmA)
Source Ranges Verification
Set up the equipment as shown in Figure 1-7 and perform
the following steps to verify the 1nA to 1OmA source
ranges:
1. Use Table l-8 to calculate the allowable readings for
the 1mA through 1OmA ranges. The values for Io.gM,
19@, Igo@, IO.CQ,A and 19n~ were previously calculated
and recorded in Table l-3. After calculating the allowable readings, transfer them to Table l-9.
2. While in standby, configure the Model 238 to source
OnA on the InA source range with a compliance limit
of 1.5V on the 1.5V measurement range.
3. While in standby, configure the Model 263 to source
On4 on the 2nA range.
4. With Zero Check enabled, zero correct the Mode1617
on the 2pA range.
5. On the Model 617, disable Zero Check and place the
Model 238 in operate. Verify that the reading on the
Model 617 is within the limits specified in the first
entry of Table l-9.
6. Set the Model 617 to the 20pA range, and set the
Model 238 to source OnA on the 1OnA range. Verify
that the reading on the Model 617 is within the limits
specified in the second entry of Table l-9.
7. Using Table l-9 as a guide, set the Model 238 to
source zero on the lOOnA through 1OmA ranges and
check that the subsequent readings are within the
listed limits.
8. Place the Model 617 in zero check and select the
20pA range.
9. Place the Model 238 in standby and program it
source -0.9nA on the 1nA source range.
10. While sti.U in standby, set the Model 263 to source
+0.9nA on the 2nA range.
11. Place both the Models 238 and 263 in operate, and
disable Zero Check on the Model 617. Verify that the
reading on the Model 617 is within the limits speci-
fied in the table.
12. Place the Model 617 in zero check, and the Models
263 and 238 in standby.
13. On both the Models 263 and 238, reverse the polarity
of the sources. That is, set the Model 238 to +0.9nA
and the Model 263 to 4.9nA.
14. Place the Models 238 and 263 in operate, and disable
zero check on the Model 617. Verify that the reading
on the Model 617 is stiU within the limits specified in
the table.
15. Using Table l-9 as a guide, repeat the basic procedure in steps 8 through 14 to check the 1OnA through
1OmA source ranges. Note that for the $A through
1OmA ranges, the source values for the Model 238 are
taken from Table l-3.
16. Place the Model 617 in zero check, and the Models
263 and 238 in standby.
Table l-8 Allowable,Reading Calculations for Low Current Source Verification (1n.A to lOmA)
238
Source
Range Reading Calculations* Lower Limit Upper Limit
WA
lOj.tA ~[(0.00050)19pA+2.00nA]= --.--- nA
lOOpA +[(0.00050)190~+20*00nA1=
1mA +[(0.00050)1o.sm~+200.0nA1=
1omA
+[(0.0005)Io.9,++2OOpAl=
~[(0.0005>19mA+2*00pA1=
- _.____ nA + _.____ nA
- __.__ nA
- _.____ /LA + _.____ /LA
- _.___ fl
Allowable Reading**
+
-----
+
__.__ nA
+
_*___ fl
nA
Typical
Limits***
+ 0.6500nA
+6.5001-A
+65.OOnA
+ 0.6500pA
+6.5OOpA
* v IV v IT ~1 * * , .- ~~~~ m-t.,. . *
+
l-13
SECTION 2
Performance Verification
+
Table 1-9 Low Current Source Verification (InA to lOmA)
263 I-Source
617
Output Source Source 617 Allowable Ratings**
Range Range Setting
2PA
2PA
20pA
22 Standby
200pA
22
2onA 2nA
Standby 1nA OnA -0.45OOpA to +0.45OOpA
Standby 1OnA OnA
Standby ~JJ.A
Standby
Standby
2oonA 2nA Standby 1mA
w4 2nA
20pA 2nA
Standby 1OmA -2.oooj.lA to +2.000)&4
+o.gllA
-0.9nA
200pA 2onA
+9nA 1onA -9nA -29.00pA to +29.OOpA
-9IL4
238 I-Source*
Range Value*** (18T to 28°C)
-2.OOOpA to +2.OOOpA
lOmA OnA -2O.OOpA to +20.OOpA
-2OO.OpA to +200.0pA
1OclA
$2
low-4 OCLA
-2.ooonA to +2.ooOnA
-2o.oonA to +2o.OOnA
-2oo.onA to +2OO.onA
iE
InA
49n4 -3.150pA to +3.15OpA
+0.9nA
+9nA
200pA 2oonA +9onA lOOIL -90nA -209.0pA to +209.0pA
-90nA i-9onA
2onA
2cLA
+0.9pA
-0.9p.A
W
2oP4 +%A lo@
-9clA
-109pA
+Io.a)lA
-19pA
fI9pl
IL4 to +
nA to +
nA
IL4
2oonA +9opA
-9opA
+o.gmA 1mA
2P4
2ooJ.L4
2mA
1OWA
-0.9m4
2lJ-A
2omA
+9mA lomA
-9mA
* 238 compliance limit set to 1.W on the 1.1V measurement range.
** Allowable readings for the 1M thru 1OmA source ranges are calculated in Table 1-8.
‘** For the 1p-l thru 1OmA ranges, program the Model 238 to source the characterized I-source values from Table 1-3.
-19@LA
S&OlrA
-1osmA
fI0.9mA
-I%4
fISmA
-
II‘4 to + IL4
I-IA to + IL4
I-IA to + nA
l-14
+
+
Interlock Cable (236~ILC-3)
Performance Verification
SECTION 1
warning: (
to Safety Ei
Ground
A. Connections
8006 Test Fixture
1
1 /ol+-gy”
238
I
Note : 617 GUARD dualled
263 source
617 Electrometer
Figure 1-7
238
(Source 1)
OUTPUTHI @
OUTPUT LO
INPUT
617
Electrometer
(Measure I)
B. Schematic Equivalent
Setup for Low Current Sou,rce Ranges Verification (InA to ZOmA)
@ OUTPUT
. COMMON Source
263
(Source I)
+
l-15
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