Lakeshore 121 Programmable DC Current Source User manual

Brand: Lakeshore

Model: 121 Programmable DC Current Source

Type: User manual

User’s Manual

Model 121

Programmable DC

Current Source

Methods and apparatus disclosed and described herein have been developed solely on

company funds of Lake Shore Cryotronics, Inc. No government or other contractual support

or relationship whatsoever has existed which in any way affects or mitigates proprietary

rights of Lake Shore Cryotronics, Inc. in these developments. Methods and apparatus dis-

closed herein may be subject to U.S. Patents existing or applied for. Lake Shore Cryotronics,

Inc. reserves the right to add, improve, modify, or withdraw functions, design modifica-

tions, or products at any time without notice. Lake Shore shall not be liable for errors con-

tained herein or for incidental or consequential damages in connection with furnishing,

performance, or use of this material.

Rev. 1.5 P/N 119-061 10 May 2018

Lake Shore Cryotronics, Inc.

575 McCorkle Blvd.

Westerville, Ohio 43082-8888 USA

[email protected]

service@lakeshore.com

www.lakeshore.com

Fax: (614) 891-1392 B Telephone: (614) 891-2243

LIMITED WARRANTY STATEMENT

WARRANTY PERIOD: THREE (3) YEARS

1.Lake Shore warrants that products manufactured by Lake Shore (the "Product") will be

free from defects in materials and workmanship for three years from the date of Pur-

chaser's physical receipt of the Product (the "Warranty Period"). If Lake Shore receives

notice of any such defects during the Warranty Period and the defective Product is shipped

freight prepaid back to Lake Shore, Lake Shore will, at its option, either repair or replace the

Product (if it is so defective) without charge for parts, service labor or associated customary

return shipping cost to the Purchaser. Replacement for the Product may be by either new

or equivalent in performance to new. Replacement or repaired parts, or a replaced Product,

will be warranted for only the unexpired portion of the original warranty or 90 days

(whichever is greater)..

2.Lake Shore warrants the Product only if the Product has been sold by an authorized Lake

Shore employee, sales representative, dealer or an authorized Lake Shore original equip-

ment manufacturer (OEM).

3.The Product may contain remanufactured parts equivalent to new in performance or

may have been subject to incidental use when it is originally sold to the Purchaser.

4.The Warranty Period begins on the date the Product ships from Lake Shore’s plant.

5.This limited warranty does not apply to defects in the Product resulting from (a) improper

or inadequate installation (unless OT&V services are performed by Lake Shore), mainte-

nance, repair or calibration, (b) fuses, software, power surges, lightning and non-recharge-

able batteries, (c) software, interfacing, parts or other supplies not furnished by Lake Shore,

(d) unauthorized modification or misuse, (e) operation outside of the published specifica-

tions, (f) improper site preparation or site maintenance (g) natural disasters such as flood,

fire, wind, or earthquake, or (h) damage during shipment other than original shipment to

you if shipped through a Lake Shore carrier.

6.This limited warranty does not cover: (a) regularly scheduled or ordinary and expected

recalibrations of the Product; (b) accessories to the Product (such as probe tips and cables,

holders, wire, grease, varnish, feed throughs, etc.); (c) consumables used in conjunction

with the Product (such as probe tips and cables, probe holders, sample tails, rods and hold-

ers, ceramic putty for mounting samples, Hall sample cards, Hall sample enclosures, etc.);

or, (d) non-Lake Shore branded Products that are integrated with the Product.

7. To the extent allowed by applicable law,, this limited warranty is the only warranty

applicable to the Product and replaces all other warranties or conditions, express or

implied, including, but not limited to, the implied warranties or conditions of merchantabi-

lity and fitness for a particular purpose. Specifically, except as provided herein,

LakeShore undertakes no responsibility that the products will be fit for any particular pur-

pose for which you may be buying the Products. Any implied warranty is limited in duration

to the warranty period. No oral or written information, or advice given by the Company, its

Agents or Employees, shall create a warranty or in any way increase the scope of this lim-

ited warranty. Some countries, states or provinces do not allow limitations on an implied

warranty, so the above limitation or exclusion might not apply to you. This warranty gives

you specific legal rights and you might also have other rights that vary from country to

country, state to state or province to province.

8.Further, with regard to the United Nations Convention for International Sale of Goods

(CISC,) if CISG is found to apply in relation to this agreement, which is specifically dis-

claimed by Lake Shore, then this limited warranty excludes warranties that: (a) the Product

is fit for the purpose for which goods of the same description would ordinarily be used, (b)

the Product is fit for any particular purpose expressly or impliedly made known to Lake

Shore at the time of the conclusion of the contract. (c) the Product is contained or packaged

in a manner usual for such goods or in a manner adequate to preserve and protect such

goods where it is shipped by someone other than a carrier hired by Lake Shore.

9. Lake Shore disclaims any warranties of technological value or of non-infringement with

respect to the Product and Lake Shore shall have no duty to defend, indemnify, or hold

harmless you from and against any or all damages or costs incurred by you arising from the

infringement of patents or trademarks or violation or copyrights by the Product.

10.THIS WARRANTY IS NOT TRANSFERRABLE. This warranty is not transferrable.

11.Except to the extent prohibited by applicable law, neither Lake Shore nor any of its sub-

sidiaries, affiliates or suppliers will be held liable for direct, special, incidental, consequen-

tial or other damages (including lost profit, lost data, or downtime costs) arising out of the

use, inability to use or result of use of the product, whether based in warranty, contract,

tort or other legal theory, regardless whether or not Lake Shore has been advised of the

possibility of such damages. Purchaser's use of the Product is entirely at Purchaser's risk.

Some countries, states and provinces do not allow the exclusion of liability for incidental or

consequential damages, so the above limitation may not apply to you.

12.This limited warranty gives you specific legal rights, and you may also have other rights

that vary within or between jurisdictions where the product is purchased and/or used.

Some jurisdictions do not allow limitation in certain warranties, and so the above limita-

tions or exclusions of some warranties stated above may not apply to you.

13.Except to the extent allowed by applicable law, the terms of this limited warranty state-

ment do not exclude, restrict or modify the mandatory statutory rights applicable to the

sale of the product to you.

CERTIFICATION

Lake Shore certifies that this product has been inspected and tested in accordance with its

published specifications and that this product met its published specifications at the time

of shipment. The accuracy and calibration of this product at the time of shipment are

traceable to the United States National Institute of Standards and Technology (NIST); for-

merly known as the National Bureau of Standards (NBS).

FIRMWARE LIMITATIONS

Lake Shore has worked to ensure that the Model 121 firmware is as free of errors as possi-

ble, and that the results you obtain from the instrument are accurate and reliable. How-

ever, as with any computer-based software, the possibility of errors exists.

In any important research, as when using any laboratory equipment, results should be

carefully examined and rechecked before final conclusions are drawn. Neither Lake Shore

nor anyone else involved in the creation or production of this firmware can pay for loss of

time, inconvenience, loss of use of the product, or property damage caused by this product

or its failure to work, or any other incidental or consequential damages. Use of our product

implies that you understand the Lake Shore license agreement and statement of limited

warranty.

FIRMWARE LICENSE AGREEMENT

The firmware in this instrument is protected by United States copyright law and interna-

tional treaty provisions. To maintain the warranty, the code contained in the firmware

must not be modified. Any changes made to the code is at the user's risk. Lake Shore will

assume no responsibility for damage or errors incurred as result of any changes made to

the firmware.

Under the terms of this agreement you may only use the Model 121 firmware as physically

installed in the instrument. Archival copies are strictly forbidden. You may not decompile,

disassemble, or reverse engineer the firmware. If you suspect there are problems with the

firmware, return the instrument to Lake Shore for repair under the terms of the Limited

Warranty specified above. Any unauthorized duplication or use of the Model 121 firmware

in whole or in part, in print, or in any other storage and retrieval system is forbidden.

TRADEMARK ACKNOWLEDGMENT

Many manufacturers and sellers claim designations used to distinguish their products as

trademarks. Where those designations appear in this manual and Lake Shore was aware of

a trademark claim, they appear with initial capital letters and the ™ or ® symbol.

Cernox® is a trademarks of Lake Shore Cryotronics, Inc.

Microsoft Windows®, Excel®, Windows XP®, and Windows Vista® are registered trademarks

of Microsoft Corporation in the United States and other countries.

manual may be reproduced, stored in a retrieval system, or transmitted, in any form or by

any means, electronic, mechanical, photocopying, recording, or otherwise, without the

express written permission of Lake Shore.

Electromagnetic Compatibility (EMC) for the Model 121

Current Source

Electromagnetic Compatibility (EMC) of electronic equipment is a growing concern world-

wide. Emissions of and immunity to electromagnetic interference is now part of the design

and manufacture of most electronics. To qualify for the CE Mark, the Model 121 meets or

exceeds the requirements of the European EMC Directive 89/336/EEC as a CLASS A prod-

uct. A Class A product is allowed to radiate more RF than a Class B product and must

include the following warning:

WARNING:This is a Class A product. In a domestic environment, this product may cause

radio interference in which case the user may be required to take adequate measures.

The instrument was tested under normal operating conditions with sensor and interface

cables attached. If the installation and operating instructions in the User's Manual are fol-

lowed, there should be no degradation in EMC performance.

This instrument is not intended for use in close proximity to RF Transmitters such as two-

way radios and cell phones. Exposure to RF interference greater than that found in a typical

laboratory environment may disturb the sensitive measurement circuitry of the instru-

ment.

Pay special attention to instrument cabling. Improperly installed cabling may defeat even

the best EMC protection. For the best performance from any precision instrument, follow

the grounding and shielding instructions in the User's Manual. In addition, the installer of

the Model 121 should consider the following:

DShield measurement and computer interface cables.

DLeave no unused or unterminated cables attached to the instrument.

DMake cable runs as short and direct as possible. Higher radiated emissions are

possible with long cables.

DDo not tightly bundle cables that carry different types of signals.

Table of Contents

Chapter 1: Introduction

1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

1.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

1.3 Model 121 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

1.3.1 Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

1.3.2 User setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

1.3.2.1 Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

1.3.2.2 Front panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

1.3.2.3 Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

1.3.3 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

1.4 Safety Summary and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Chapter 2: Installation

2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

2.2 Inspecting and Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

2.3 Rear Panel Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2.4 Power Input Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

2.5 External Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

2.6 Cable Clamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.7 Current Source Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.7.1 Current Source Output Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.7.2 Sensor Lead Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.7.3 Grounding and Shielding Sensor Leads . . . . . . . . . . . . . . . . . . . . . . 11

2.7.4 Sensor Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.7.4.1 Resistive Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.7.4.2 Diode Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.7.4.3 Hall Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.7.5 Lowering Measurement Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.8 Rack Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Chapter 3: Operation

3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2 Instrument Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.3 Front Panel Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3.1 Keypad Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3.2 Display Annunciators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.4 Display Brightness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.5 Output Current Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.5.1 Enable/Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

3.5.2 Range Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

3.5.3 Polarity Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

3.5.4 User Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

3.5.5 Power Up Enable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

3.6 Power Up State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

3.7 Locking and Unlocking the Keypad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Chapter 4: Computer Interface Operation

4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

4.2 USB Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

4.2.1 Physical Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

4.2.2 Hardware Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4.2.3 Installing the USB Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

4.2.3.1 Installing the Driver From Windows® Update in

Windows® 7 and Vista® . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

4.2.3.2 Installing the Driver From Windows® Update

in Windows® XP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

4.2.3.3 Installing the Driver from the Web . . . . . . . . . . . . . . . . . .23

4.2.3.3.1 Download the driver . . . . . . . . . . . . . . . . . . . . . . . .23

4.2.3.3.2 Extract the driver . . . . . . . . . . . . . . . . . . . . . . . . . . .23

4.2.3.3.3 Manually install the driver . . . . . . . . . . . . . . . . .24

4.2.4 Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

4.2.4.1 Character Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

4.2.4.2 Message Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

4.2.5 Message Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

4.3 Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

4.3.1 Interface Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Chapter 5: Options and Accessories

5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

5.2 Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

5.3 Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Chapter 6: Service

6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

6.2 USB Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

6.2.1 New Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

6.2.2 Existing Installation No Longer Working . . . . . . . . . . . . . . . . . . . . 38

6.2.3 Intermittent Lockups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

6.3 Factory Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

iii

6.4 Product Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

6.5 Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

6.6 Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

6.7 Rear Panel Connector Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

6.8 Firmware Updates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

6.8.1 Updating the Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

6.8.2 Record of Updates Made to the Firmware . . . . . . . . . . . . . . . . . . . 41

6.9 Technical Inquiries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6.9.1 Contacting Lake Shore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6.9.2 Return of Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6.9.3 RMA Valid Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

6.9.4 Shipping Charges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

6.9.5 Restocking Fee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Appendix A: Handling Liquid Helium and Nitrogen

A.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

A.2 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

A.3 Handling Cryogenic Storage Dewars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

A.4 Liquid Helium and Nitrogen Safety Precautions . . . . . . . . . . . . . . . . . . . 46

A.5 Recommended First Aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Appendix B: Regulatory Declarations

B.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

B.1.1 CE Declaration for Model 121 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

B.1.2 CE Declaration for the Power Supply,

Part Number 109-132 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Chapter 1: Introduction

1.1 Overview

The Model 121 programmable DC current source is a precision instru-

ment suitable for bench-top use or panel-mounted operation in labs,

test facilities, and manufacturing environments. It provides a low noise,

highly-stable source of current up to 100 mA, with convenient manual

selection through 13 pre-set output levels, each representing a ten-fold

change in power when attached to a resistive load. A “user” setting

allows the current output to be defined anywhere within the operating

range of the unit, from 100 nA to 100 mA.

Programmable operation is also possible via the instrument’s USB com-

puter interface, through which the Model 121 can be commanded to

output any desired current at any time. Thus, application-specific test

currents can be driven from an external PC.

The instrument operates at 5 VDC, and power is supplied by the external

AC wall-mount supply provided with the standard Model 121. The sup-

ply will automatically conform to any AC line voltage ranging from

100 VAC to 240 VAC, 50 or 60 Hz.

D7 decades of output current, selectable in 13 steps

DProgrammable current output, 100 nA to 100 mA

DLow-noise output

DLarge 3 digit LED display

DSimple user interface

DCurrent reversal feature

DUSB interface enables integration with automated test systems

DDIN panel-mountable package

DDetachable output terminal block

DCE mark certification

2 CHAPTER 1: Introduction

1.2 Applications

The Model 121 current source is ideally suited for testing, measuring,

and operating resistive and semiconductor devices, such as:

DLake Shore Cernox™ temperature sensors

DOther resistance temperature detectors (RTDs) such as platinum

sensors

DDiode temperature sensors, including Lake Shore DT-670’s

DLED devices

DHall sensors used for magnetic field measurement

An accurate, stable source of current is key to ensuring consistent opera-

tion of these devices, where the voltage drop across the device can be

dependent upon temperature, magnetic field, and other parameters.

The instrument's wide output range is of great value when used with

RTD-type sensors whose resistance can vary with temperature by as

much as 6 orders of magnitude. The current reversal feature enables

compensation for thermal EMF, important for accurately measuring

resistors at very low excitation levels.

Example applications include:

DBasic device QC ("good/bad" verification)

DLED brightness testing (constant device current)

DTemperature sensor calibration (determine resistance at fixed cali-

bration points)

DTemperature measurement (using a voltmeter readout)

DMagnetic sensor calibration and measurement

DSemiconductor device measurements (IV curves for diodes, transis-

tors, etc.)

DCircuit prototyping (fixed current source)

DSmall scale electro-chemical applications

Whether operating over a wide range of environmental conditions,

establishing precise sensor calibrations or simply testing devices for

conformance, the Model 121 provides a convenient and reliable alterna-

tive to simple voltage-based circuits, and a very affordable alternative to

more expensive multi-function current sources. It can be readily inte-

grated into automated test systems using its built-in USB computer

interface and offers a highly readable, simple-to-use operator display.

1.3 Model 121 Specifications

1.3.1 Output

Type: Bipolar, DC current source

Current ranges: 13 fixed ranges of 100 nA, 300 nA, 1 µA, 3 µA, 10 µA, 30

µA, 100 µA, 300 µA, 1 mA, 3 mA, 10 mA, 30 mA, 100 mA, and a user-pro-

grammable range

Accuracy: 0.05% on 10 µA range, 0.5% on 100 nA and 300 nA ranges,

0.1% on all other ranges

Compliance voltage: ±11 V up to 30 mA, ±10 V up to 100 mA

AC current ripple: < 0.1% on 100 nA and 300 nA ranges; < 0.01% on all

other ranges in a properly shielded system

Current ripple frequency: Dominated by line frequency and its

harmonics

Temperature coefficient: 0.03% of range/°C for the 100 nA range,

0.01% of range/°C for all other ranges

Line regulation: < 0.01% change in output for 5% change in the DC input

voltage

Load regulation: < 0.01% change in output current over the full-scale

range

Stability (24 h): 0.05% on 100 nA range, 0.01% per day on all other fixed

ranges

Settling time: <300 ms for full-scale change in current; <100 ms for 10%

change in current

Connector: Detachable terminal block

Maximum load: 300 k

1.3.2 User setting

1.3.2.1 Programming

Operation: Output current settable via computer interface

Resolution: 3 significant digits

Accuracy: 0.5% for currents <300 nA, 0.25% for all other currents

Maximum current: 100 mA

Minimum current: 100 nA

4 CHAPTER 1: Introduction

1.3.2.2 Front panel

Display: 6-digit LED display

Display units: mA, µA, and nA

Display update rate: 2 rdg/s

Display anunciators: mA, µA, nA, and compliance

Keypad: 4 full-travel keys

Keypad functions: Range Up, Range Down, Current Polarity,

Enable/Disable

1.3.2.3 Interface

USB Function: Emulates an RS-232 serial port

Baud rate: 57,600

Connector: B-type USB connector

Reading rate: Up to 10 rdg/s

Software support: LabVIEW™ driver (consult Lake Shore for availability)

1.3.3 General

Ambient temperature: 15 °C to 35 °C at rated accuracy; 5 °C to 40 °C at

reduced accuracy

Power requirement: +5 VDC ±5% at 250 mA, barrel plug 5.5 mm OD ×

2.1 mm ID × 9.9 mm L

Size: 96 mm W × 48 mm H × 166 mm D (3.8 in × 1.9 in × 6.5 in)

Mounting: Panel mount into 91 mm W × 44 mm H (3.6 in × 1.7 in) cutout

Weight: 0.45 kg (1 lb)

Approval: CE Mark

1.4 Safety Summary and Symbols

Observe these general safety precautions during all phases of instru-

ment operation, service, and repair. Failure to comply with these precau-

tions or with specific warnings elsewhere in this manual violates safety

standards of design, manufacture, and intended instrument use. Lake

Shore Cryotronics, Inc. assumes no liability for Customer failure to com-

ply with these requirements.

The Model 121 protects the operator and surrounding area from electric

shock or burn, mechanical hazards, excessive temperature, and spread

of fire from the instrument. Environmental conditions outside of the

conditions below may pose a hazard to the operator and surrounding

area.

DIndoor use

DAltitude to 2000 m

DTemperature for safe operation: 5 °C to 40 °C

DMaximum relative humidity: 80% for temperature up to 31 °C

decreasing linearly to 50% at 40 °C

DPower supply voltage fluctuations not to exceed ±10% of the nomi-

nal voltage*

DOvervoltage category II

DPollution degree 2

*The power supply included with the Model 121 meets or exceeds the European

Union Standard, EN-60950.

Do Not Operate in an Explosive Atmosphere

Do not operate the instrument in the presence of flammable gases or

fumes. Operation of any electrical instrument in such an environment

constitutes a definite safety hazard.

Keep Away from Live Circuits

Operating personnel must not remove instrument covers. Refer compo-

nent replacement and internal adjustments to qualified maintenance

personnel. Do not replace components with power cable connected. To

avoid injuries, always disconnect power and discharge circuits before

touching them.

Do Not Substitute Parts or Modify Instrument

Do not install substitute parts or perform any unauthorized modification

to the instrument. Return the instrument to an authorized Lake Shore

Cryotronics, Inc. representative for service and repair to ensure that

safety features are maintained.

Cleaning

Do not submerge instrument. Clean only the exterior of the instrument

with a damp cloth and mild detergent.

6 CHAPTER 1: Introduction

FIGURE 1-1 Safety symbols

Direct current (power line) Equipment protected throughout

by double insulation or reinforces

insulation (equivalent to Class II of

IEC 536—see Annex H)

CAUTION: High voltages; danger of

electric shock; background color:

yellow; symbol and outline: black

CAUTION or WARNING: See

instrument documentation;

background color: yellow;

symbol and outline: black

Off (supply)

On (supply)

Frame or chassis terminal

Protective conductor terminal

Earth (ground) terminal

3Three-phase alternating current (power line)

Alternating or direct current (power line)

Alternating current (power line)

Chapter 2: Installation

2.1 General

This chapter provides general installation instructions for the Model 121

current source. Please read this entire chapter before installing the

instrument and powering it on to ensure the best possible performance

and maintain operator safety. For instrument operating instructions

refer to Chapter 3. For computer interface installation and operation

refer to Chapter 4.

2.2 Inspecting and Unpacking

Inspect shipping containers for external damage before opening them.

Photograph any container that has significant damage before opening

it. Inspect all items for both visible and hidden damage that may have

occurred during shipment. If there is visible damage to the contents of

the container, contact the shipping company and Lake Shore immedi-

ately, preferably within five days of receipt of goods, for instructions on

how to file a proper insurance claim. Lake Shore products are insured

against damage during shipment, but a timely claim must be filed before

Lake Shore will take further action. Procedures vary slightly with ship-

ping companies. Keep all damaged shipping materials and contents until

instructed to either return or discard them.

Open the shipping container and keep the container and shipping mate-

rials until all contents have been accounted for. Check off each item on

the packing list as it is unpacked. Instruments themselves may be

shipped as several parts. The items included with the Model 121 are

listed below. Contact Lake Shore immediately if there is a shortage of

parts or accessories. Lake Shore is not responsible for any missing items

if not notified within 60 days of shipment.

If the instrument must be returned for recalibration, replacement or

repair, a Return Authorization (RMA) number must be obtained from a

factory representative before it is returned. Refer to section 6.9.3 for the

Lake Shore RMA procedure.

Items Included with Model 121 current source:

D1 Model 121 instrument

D1 Model 121 user’s manual

8 CHAPTER 2: Installation

D1 terminal block mating connector, 2-pin terminal block, for current

source output (G-106-735)

D4 adhesive square rubber feet

D1 cable clamp, for power supply cord

D1 universal input power supply (interchangeable plug style)*

(109-132)

* Not included with the 121N option

2.3 Rear Panel Definition

This section provides a description of the Model 121 rear panel connec-

tions, as shown in FIGURE 2-1. The rear panel consists of the current

source output connector, USB B-type connector, and power jack. Instal-

lation information for each feature is outlined throughout the next few

sections. A summary of the connector pin-outs is provided in section 6.7.

Always remove power from the instrument before

making any rear panel connections. This is especially

critical when making sensor to instrument connec-

tions.

FIGURE 2-1 Model 121 rear panel

2.4 Power Input Connector

Power is supplied to the Model 121 through a coaxial connector located

on the rear panel of the instrument. There is no power switch on the

instrument, so it is off when not plugged in, and on when plugged in.

Make sensor connections before applying power to the instrument.

The instrument requires +5 VDC at 250 mA. The coaxial connector

accepts a barrel plug 5.5 mm OD x 2.1 mm x 9.9 mm L. Refer to

FIGURE 2-2 for polarity.

To prevent electrical fire or shock hazards, do not

expose this instrument, or its power supply, to rain or

excess moisture.

2.5 External Power Supply

The Model 121 comes with the universal input power supply, Lake Shore

P/N 109-132. It can accept input voltages from 100 to 240 VAC (±10%),

50 or 60 Hz. For input power, it has interchangeable plugs to accommo-

date power receptacles in different countries. It has a barrel plug for the

output. It can output +5 VDC at 1.2 A. The power supply is CE certified

and meets or exceeds the following safety standards: UL 60950-1 and

EN 60950. To change plugs, press the pad on the side of the plug, pull off

the old plug, and snap in the new plug.

FIGURE 2-2 Power connector

Pin Description

Inner conductor +5 V

Outer conductor2 Ground

TABLE 2-1 Power input connector details

10 CHAPTER 2: Installation

2.6 Cable Clamp

To avoid inadvertent disconnection from the power supply, Lake Shore

supplies a cable clamp that the user may attach to the cord and the

instrument chassis. It is a part of the accessories kit supplied with the

unit. To install the clamp, remove the screw at the top left rear of the

unit, position the cord and clamp as shown in the photo and reinstall the

screw.

2.7 Current Source Output

This section details how to connect various sensors to the Model 121

output. Refer to section 3.5 to configure the outputs.

2.7.1 Current Source Output Connector

The output connector is a 2-pin terminal block. The output connector

pins are defined in FIGURE 2-4 and TABLE 2-2. One mating connector

(terminal block mate) is included in the connector kit shipped with the

instrument. These are common connectors, so additional mating con-

nectors can be purchased from local electronics suppliers. They can also

be ordered from Lake Shore as G-106-735.

I- cannot be connected to chassis ground.

FIGURE 2-3 Cable clamp for the Model 121

+5V

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Lakeshore 121 Programmable DC Current Source User manual

Brand: Lakeshore

Model: 121 Programmable DC Current Source

Type: User manual

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Lakeshore 121 Programmable DC Current Source User manual

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