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Lake Shore Cryotronics 121 User Manual

Programmable dc current source
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User's Manual
Model 121
Programmable DC
Current Source
Lake Shore Cryotronics, Inc.
sales@lakeshore.com
575 McCorkle Blvd.
service@lakeshore.com
Westerville, Ohio 43082-8888 USA
www.lakeshore.com
Fax: (614) 891-1392 B Telephone: (614) 891-2243
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

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Summary of Contents for Lake Shore Cryotronics 121

  • Page 1 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.
  • Page 2 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...
  • Page 3 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.
  • Page 4 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.
  • Page 5 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.

  • Page 7: Table Of Contents

    1.3 Model 121 Specifications ........
  • Page 8 3.5.1 Enable/Disable ..........17 3.5.2 Range Change .
  • Page 9 B.1 General ............. 49 B.1.1 CE Declaration for Model 121 ....... 50 B.1.2 CE Declaration for the Power Supply,...

  • Page 11: Chapter 1: Introduction

    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.

  • Page 12: Applications

    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: Lake Shore Cernox™ temperature sensors Other resistance temperature detectors (RTDs) such as platinum sensors Diode temperature sensors, including Lake Shore DT-670’s...

  • Page 13: Model 121 Specifications

    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,...

  • Page 14: Front Panel

    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.
  • Page 15 Overvoltage category II Pollution 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.
  • Page 16 6 CHAPTER 1: Introduction Equipment protected throughout Direct current (power line) by double insulation or reinforces insulation (equivalent to Class II of Alternating current (power line) IEC 536—see Annex H) Alternating or direct current (power line) CAUTION: High voltages; danger of electric shock;...

  • Page 17: Chapter 2: Installation

    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.

  • Page 18: Rear Panel Definition

    * 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.

  • Page 19: Power Input Connector

    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.

  • Page 20: Cable Clamp

    FIGURE 2-3 Cable clamp for the Model 121 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.

  • Page 21: Sensor Lead Cable

    (109-132) does not carry earth ground through to chassis. To meet the accuracy specifications at lower current levels the Model 121 must be in a properly shielded system. Since the Model 121 is not connected to earth ground it is important to tie it to measurement...

  • Page 22: Sensor Polarity

    12 CHAPTER 2: Installation ground connection on the rear panel. It is also advised to use sensor leads that are shielded and floating. The shield should be tied to mea- surement common. When making any such connections, it is important to avoid ground loops by connecting measurement commons at one point.

  • Page 23: Hall Generators

    2.7.4.3 Hall Generators With Hall generators the direction of the current and magnetic field are important to determining the sign of the Hall voltage. As shown in FIG- URE 2-6, the current enters the red lead (with +I connected to the posi- tive terminal of the current supply), and the magnetic field direction B is into the page.

  • Page 24: Lowering Measurement Noise

    The Model 121 can be easily mounted using the panel mount brackets included. The Model 121 fits in a 91 × 44 mm (3.6 × 1.7 in) cutout. To panel-mount the instrument, unplug the unit and use a 1/bg -inch hex wrench to remove the two set screws holding the brackets in place.

  • Page 25: Chapter 3: Operation

    FIGURE 3-1 Model 121 front panel 3.2 Instrument Power The Model 121 is powered on by plugging in the power supply. There is no power switch on the instrument. When the Model 121 is powered on, with no errors present, “121” will illuminate for a few seconds to indi- cate instrument initialization.

  • Page 26: Front Panel Description

    There are also four keys that allow for manually changing the range, polarity, or disabling the current source output. 3.3.1 Keypad Definitions The keypad for the Model 121 consists of four keys as described in TABLE 3-1. Function Refer to section Allows the user to change the polarity of the output section 3.5.3...

  • Page 27: Display Brightness

    (such as Cernox and Platinum Sensors), diode sensors, and Hall genera- tors. 3.5.1 Enable/Disable The Model 121 allows the user to turn on or turn off the output current by pressing . When this key is pressed, the display will either read “off”...

  • Page 28: Polarity Change

    Interface Command: RANGE 3.5.3 Polarity Change The Model 121 allows for the user to switch the polarity of the current by pressing +/-. This key will switch the polarity of the output current for any of the fixed ranges and user current. The +/- key works inde- pendently for the fixed ranges and user current range.

  • Page 29: User Current

    Interface Command: PWUPENBL 3.6 Power Up State The Model 121 can be programmed to power up in a user defined state called the power up state. The power up state consists of three setup parameters: range, polarity, and user current value. To save the power up state, configure the instrument with the desired settings, then press and hold +/- for 3 s.

  • Page 30: Locking And Unlocking The Keypad

    20 CHAPTER 3: Operation 3.7 Locking and Unlocking the Keypad The keypad lock feature prevents accidental changes to parameters. When the keypad is locked, the front panel is completely disabled. To lock the instrument, hold down for 3 s, until the display reads “LOC”.

  • Page 31: Chapter 4: Computer Interface Operation

    USB implementation. 4.2.1 Physical Connection The Model 121 has a B-type USB connector on the rear panel. This is the standard connector used on USB peripheral devices, and it allows the common USB A-type to B-type cable to be used to connect the Model 121 to a host PC.

  • Page 32: Installing The Usb Driver

    4.2.3.1 Installing the Driver From Windows® Update in Windows® 7 and Vista® 1. Connect the USB cable from the Model 121 to the computer. 2. Turn on the Model 121. 3. When the Found New Hardware wizard appears, select Locate and install driver software (recommended).

  • Page 33: Installing The Driver From Windows® Update

    Windows® 7, Vista®, and XP. 4.2.3.3.1 Download the driver 1. Locate the Model 121 USB driver on the downloads page on the Lake Shore website. 2. Right-click on the USB driver download link, and select save target/ link as.

  • Page 34: Manually Install The Driver

    For Windows® 7 and Vista®: 1. Connect the USB cable from the Model 121 to the computer. 2. Turn on the Model 121. 3. If the Found New Hardware wizard appears, click “ask me again later.”...
  • Page 35 Lake Shore Model 121, it might be displayed as USB Device. If nei- ther are displayed, click Action and then Scan for hardware changes, which may open the Found New Hardware wizard automatically. If the Found New Hardware wizard opens, click Cancel.

  • Page 36: Communication

    7. Click Next. 8. When the driver finishes installing a confirmation message stating “The wizard has finished installing the software for Lake Shore Model 121 Current Source” should appear. Click Finish to complete the installation. 4.2.4 Communication Communicating via the USB interface is done using message strings. The...

  • Page 37: Message Flow Control

    A command string is issued by the computer and instructs the instru- ment to perform a function or change a parameter setting. The format is: <command mnemonic><space><parameter data><terminators>. Command mnemonics and parameter data necessary for each one is described in section 4.3. Terminators must be sent with every message string.
  • Page 38 28 CHAPTER 4: Computer Interface Operation Properly format and transmit the query including the terminator as one string Prepare to receive a response immediately Receive the entire response from the instrument including the ter- minator Guarantee that no other communication is started during the response or for 50 ms after it completes Not initiate communication more than 20 times per second Failure to follow these simple rules will result in inability to establish...

  • Page 39: Command Summary

    4.3 Command Summary This section provides a listing of the interface commands. A summary of all the commands is provided in TABLE 4-2. All the commands are detailed in section 4.3.1, and are presented in alphabetical order. Command name Brief description of command RANGE Form of the command input Current Range Command...

  • Page 40: Interface Commands

    30 CHAPTER 4: Computer Interface Operation Command Function Page IDN? Identification Query page 31 RST Reset Instrument Command page 31 BRIGT Display Contrast Command page 31 BRIGT? Display Contrast Query page 31 COMP? Compliance Limit Query page 31 DFLT Factory Defaults Command page 32 IENBL Current Enable Command...
  • Page 41 IDN? Identification Query IDN?[term] Input Format s[4],s[8],s[7],n.n <manufacturer> Manufacturer ID <model> Instrument model number <instrument serial> Instrument serial number <firmware version> Instrument firmware version Example LSCI,MODEL121,1234567,1.0 RST Reset Instrument Command RST[term] Input Remarks Sets instrument parameters to power-up settings. BRIGT Display Brightness Command Input BRIGT<display contrast>[term]...
  • Page 42 32 CHAPTER 4: Computer Interface Operation DFLT Factory Defaults Command Input DFLT 99[term] Remarks Sets all configuration values to factory defaults and resets the instrument. The “99” is included to prevent accidentally setting the unit to defaults. IENBL Current Enable Command Input IENBL<state>[term] Format...
  • Page 43 LOCK Front Panel Keypad Lock Command Input LOCK<state>[term] Format <state> 0 = unlock, 1 = lock Remarks Allows for the user to lock or unlock the front panel keypad LOCK? Front Panel Keypad Lock Query Input LOCK?[term] Format n (refer to command for description) Returned <state>{term] PWUPENBL...
  • Page 44 34 CHAPTER 4: Computer Interface Operation RANGE? Current Range Query Input RANGE?[term] Format Returned <numeric key value>[term] SETI Set User Current Command Input SETI Format ±nnne-nn <user current value> Current value as a three- digit number including a decimal place Remarks User current is settable between 100 nA and 100 mA.

  • Page 45: Chapter 5: Options And Accessories

    This chapter provides information on the models, options, and accesso- ries available for the Model 121 current source. 5.2 Models The list of Model 121 model numbers is provided in TABLE 5-1. Model Description of Models Model 121 current source...
  • Page 46 36 CHAPTER 5: Options and Accessories...

  • Page 47: Chapter 6: Service

    In Microsoft Windows®, the device status can be checked using Device Manager by right-clicking Lake Shore Model 121 Current Source under Ports (COM & LPT) or Other Devices and then clicking Properties. Refer to section 4.2.3 for details on install- ing the USB driver.

  • Page 48: Existing Installation No Longer Working

    2. Increase the delay between all commands to 100 ms to make sure the instrument is not being overloaded. 3. Ensure that the USB cable is not unplugged and that the Model 121 is not powered down while the com port is open. The USB driver cre- ates a com port when the USB connection is detected, and removes the com port when the USB connection is no longer detected.

  • Page 49: Factory Reset

    6.5 Error Messages The following are error messages that may be displayed by the Model 121 during operation. Message Description There is a hardware problem in the instrument memory. This error is not correctable by Err1 the user and the factory should be consulted.

  • Page 50: Rear Panel Connector Definition

    40 CHAPTER 6: Service 6.7 Rear Panel Connector Definition The terminal block, USB connector, and power supply connector are defined in FIGURE 6-1, FIGURE 6-2, and FIGURE 6-3. Pin 2 Pin 1 FIGURE 6-1 Terminal block for output of current source Description Current–...

  • Page 51: Firmware Updates

    Periodically, Lake Shore provides updates to instrument firmware. The files for these updates can be downloaded from our website. To access the firmware updates, follow this procedure. 1. Go to 121 website page (http://www.lakeshore.com/products/DC- Current-Sources/Model-121-DC-Current-Source/Pages/Over- view.aspx) to download the instrument firmware.

  • Page 52: Technical Inquiries

    You will receive a response within 24 hours or the next business day in the event of weekends or holidays. If you wish to contact Service or Sales by mail or telephone, use the following: Lake Shore Cryotronics Instrument Service Department Mailing address 575 McCorkle Blvd.

  • Page 53: Rma Valid Period

    If the original packaging is not available, a minimum of 76.2 mm (3 in) of shock absorbent packing material should be placed snugly on all sides of the instrument in a sturdy corrugated cardboard box. Please use reason- able care when removing the temperature controller from its protective packaging and inspect it carefully for damage.
  • Page 54 44 CHAPTER 6: Service...

  • Page 55: Appendix A: Handling Liquid Helium And Nitrogen

    Use of liquid helium (LHe) and liquid nitrogen (LN ) is often associated with the Model 121 current source. Although not explosive, there are a number of safety considerations to keep in mind in the handling of LHe and LN A.2 Properties...

  • Page 56: Handling Cryogenic Storage Dewars

    46 APPENDICES A.3 Handling Cryogenic Storage Dewars Cryogenic containers (Dewars) must be operated in accordance with the manufacturer instructions. Safety instructions will also be posted on the side of each Dewar. Cryogenic Dewars must be kept in a well-ventilated place where they are protected from the weather and away from any sources of heat.
  • Page 57 Liquid helium and liquid nitrogen are potential asphyxiants and can cause rapid suffocation without warning. Store and use in area with adequate ventila- tion. DO NOT vent container in confined spaces. DO NOT enter confined spaces where gas may be present unless area has been well ventilated.

  • Page 58: Recommended First Aid

    48 APPENDICES A.5 Recommended First Aid Every site that stores and uses LHe and LN2 should have an appropriate Material Safety Data Sheet (MSDS) present. The MSDS may be obtained from the manufacturer/distributor. The MSDS will specify the symptoms of overexposure and the first aid to be used. A typical summary of these instructions is provided as follows.

  • Page 59: Appendix B: Regulatory Declarations

    121 programmable DC current source beginning with serial number 121000A and subsequent, as well as its power supply. Paragraph B1.1 refers to the CE declaration for the Model 121 alone. Paragraphs B1.2 through B1.5 refer to the CE and RoHS declarations respectively for the unit’s power supply.

  • Page 60: Ce Declaration For Model 121

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

  • Page 61: Ce Declaration For The Power Supply

    B.1.2 CE Declaration for the Power Supply, Part Number 109-132...
  • Page 62 52 APPENDICES...

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