Joulescope JS220 User Manual
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Joulescope JS220 User Manual

Precision dc energy analyzer
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Joulescope™ JS220 User's Guide
Precision DC Energy Analyzer
Revision 1.3
Last revised 2022 October 25
Revision 1.3
Joulescope JS220 User's Guide
Page 1 / 51
www.joulescope.com

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  • Page 1 Joulescope™ JS220 User’s Guide Precision DC Energy Analyzer Revision 1.3 Last revised 2022 October 25 Revision 1.3 Joulescope JS220 User’s Guide Page 1 / 51 www.joulescope.com...

  • Page 2: Affordable, Easy-To-Use, Accurate And Precise

    The unprecedented accuracy and low-cost of Joulescope allows every engineer on the team to measure the energy consumed by the target device during development. Joulescope provides rapid feedback on how changes affect the overall product battery life.

  • Page 3: Key Benefits

    (sometimes called burden voltage or insertion loss), which affects the actual voltage delivered to the device under test. Joulescope has a total voltage drop of 25 mV at 1 A, which keeps your target device running correctly. Joulescope’s extremely fast current range switching maintains low voltage drop even under rapidly varying current demands.

  • Page 4: Key Features

    • Host software is open source and available on GitHub • Swappable front panel with open-source designs on GitHub • Firmware upgradable See Section 7 for the full specifications. Revision 1.3 Joulescope JS220 User’s Guide Page 4 / 51 www.joulescope.com...

  • Page 5: Table Of Contents

    4. Table of contents Affordable, easy-to-use, accurate and precise ..................2 Key benefits............................3 Key features ............................4 Table of contents ..........................5 Meet Your Joulescope JS220 ......................... 8 Quick start ............................11 Specifications ............................13 7.1. Absolute maximum ratings ......................13 7.2.
  • Page 6 RoHS Directive 2011/65/EU, 2015/863/EU ................44 16.6. Country of origin ........................44 Warranty ............................45 Intellectual Property ........................46 Contact ............................47 Glossary ............................48 User’s guide information ........................ 50 Revision 1.3 Joulescope JS220 User’s Guide Page 6 / 51 www.joulescope.com...
  • Page 7 21.1. Copyright notice ........................50 21.2. Publisher ..........................50 21.3. Warranty ..........................50 21.4. Change log ..........................51 Revision 1.3 Joulescope JS220 User’s Guide Page 7 / 51 www.joulescope.com...

  • Page 8: Meet Your Joulescope Js220

    5. Meet Your Joulescope JS220 The JS220 arrives in a carry case: Unzip the carry case to find the JS220 instrument and accessories: Revision 1.3 Joulescope JS220 User’s Guide Page 8 / 51 www.joulescope.com...
  • Page 9 For more connection examples, see Section 9. The Sensor Status indicator is off when your JS220 is powered off or inactive. Flashing red indicates that the instrument is ready but the current flow is not yet enabled. Solid green indicates that current measurement is enabled.
  • Page 10 If your computer only has USB C ports, use an adapter (not provided) or a USB C to USB C cable (not provided). The Controller Status indicator is off when the JS220 is not connected to the host computer, or the host computer has not yet activated the JS220 over USB. Microsoft Windows computers activate devices immediately when connected while macOS and Linux do not active the device until the Joulescope software attempts to use the device.

  • Page 11: Quick Start

    8.1 for details. Start the Joulescope host software. Connect the Joulescope USB port to the host computer using the provided USB cable. The host software will automatically detect the connected Joulescope and start displaying data. To measure the current and charge, connect the Joulescope Current port inline between the positive output from your power source and your target device under test.
  • Page 12 Dive into more detail with the oscilloscope view. Select View → Oscilloscope Default to display waveforms of voltage, current, and power over time. Revision 1.3 Joulescope JS220 User’s Guide Page 12 / 51 www.joulescope.com...

  • Page 13: Specifications

    7.2. Mechanical 7.2.1. Instrument Only Typical Unit Weight grams Width Length (including binding posts and BNC connector) Height 7.2.2. Complete product kit Typical Unit Weight grams Width Length Height Revision 1.3 Joulescope JS220 User’s Guide Page 13 / 51 www.joulescope.com...

  • Page 14: Recommended Operating Conditions

    The JS220 is sensitive to RF radiation which induces real current in test setups. When tested with EN61326-1 and 3 V RMS/m, the JS220 measured up to 10 µA (observed, not guaranteed) of current at several frequencies. The exact frequency susceptibility varies with cable length and configuration.

  • Page 15: General Specifications

    The JS220 is sensitive to RF radiation which induces real voltages in test setups. When tested with EN61326-1 and 3 V RMS/m, the JS220 error increased by 10 mV (observed, not guaranteed) at several frequencies. The exact frequency susceptibility varies with cable length and configuration.
  • Page 16 The Joulescope uses the TI SN74LVC2T45 for both the GPIs and GPOs. See the SN74LVC2T45 datasheet for more information. Both the GPIs and GPOs are protected with the TI TPD4E1U06 for ESD protection. Revision 1.3 Joulescope JS220 User’s Guide Page 16 / 51...

  • Page 17: Host Software

    8. Host software The Joulescope host software runs on a host computer and communicates with the Joulescope JS220 instrument over USB 2.0 high-speed. The software works with Microsoft® Windows® 11 and 10, Apple® macOS® 12 and 10.15, and Linux®. For Linux, only Ubuntu 22.04 LTS is officially supported. The Joulescope software only supports 64-bit operating systems with 64-bit Python 3.8+.
  • Page 18 Power in watts (W) • Energy in joules (J) • Charge in either coulombs I or amp-hours (Ah). This display, along with all other value displays in the Joulescope software, the SI standard prefixes for orders of magnitude: Prefix Power Name...

  • Page 19: Oscilloscope View

    Preferences → Units → Accumulator to set the displayed field to either energy or current. The software displays two different waveforms by default. The top waveform is electrical current, and the bottom waveform is electrical voltage. The x-axis is time. If you have a Joulescope connected, it will Revision 1.3 Joulescope JS220 User’s Guide...
  • Page 20 The y-axis data is the value measured at the corresponding point in time. Joulescope captures data 2 million times per second. When zoomed out, each x-axis pixel may represent many, many samples, which are that pixel’s sample window.
  • Page 21 Press the left mouse button and drag the cursor left or right to pan in time. Pan is not supported when viewing live data from a Joulescope. The software displays the waveform on a linear scale with automatic y-axis ranging by default. The y- axis context menu has additional options.

  • Page 22: Energy And Charge

    The Joulescope measures current and voltage two million times per second. It then multiplies current by voltage to compute power. Joulescope then integrates power over time to compute energy. It also integrates current to compute charge. Joulescope displays energy in both the Multimeter view and Oscilloscope view.
  • Page 23 • https://github.com/jetperch/pyjoulescope • https://github.com/jetperch/joulescope_driver • https://github.com/jetperch/jls You can find examples for how to use Joulescope in your Python application at: https://github.com/jetperch/pyjoulescope_examples Also see the documentation: https://joulescope.readthedocs.io/ The Joulescope software depends upon other software and libraries. See CREDITS.html for pyjoulescope_ui and pyjoulescope.

  • Page 24: How To Connect Your Joulescope

    Measure only current (ammeter) The Joulescope JS220 features independent current and voltage channels. You can use your Joulescope JS220 to measure the current through any wire. The JS220 will also compute total charge, the integral of current. The following figure shows a simple current source with a wire. The current source polarity and arrow are for convention only, and current can flow in both directions.

  • Page 25: Measure Only Voltage (Voltmeter)

    During normal operation, the JS220 is designed to keep the voltage at I+ almost equal to the voltage I-. The JS220 uses a resistor to sense the current flowing between I+ and I-, but it limits the shunt resistor voltage to 20 mV maximum, at least for all current under 2 A.

  • Page 26: Measure Power Supply Provided

    I+ to measure correctly. The easiest way to ensure this condition is to connect I+ and V+ as shown. Also ensure that the JS220 Current Range is set to anything other than off. Unlike most test equipment, the voltage inputs are completely floating and isolated, so you need to make this connection.
  • Page 27 The target device under test can include product prototypes, custom hardware under development, development boards, systems, and subsystems. The easiest way to connect your JS220 is as an ammeter measuring current in the + wire and as a voltmeter across the power source PS+ and PS-, like this: Revision 1.3...

  • Page 28: Measure Target Device Consumption

    IN+ to PS+, IN- to PS-, OUT+ to T+, and OUT- to T-. The FP02-BNA front panel provides the JS220 with the exact same connections as the JS110. The JS220 can alternatively be used to measure current on the low-side wire connected to PS-. 9.4.

  • Page 29: Measure Subsystem Consumption

    RF transmitter, you do not want the cables too short. You want to ensure that the JS220 does not become part of the antenna. A good rule of thumb is that you should locate all test equipment one wavelength away from the RF transmitter. One wavelength is approximately 33 cm at 915 MHz and 12 cm at 2.4 GHz.
  • Page 30 This connection recommendation shows a Kelvin-style 4-wire connection, which helps improve accuracy and minimize noise pickup. Connect the JS220 using two wire pairs, one to measure current and one to measure voltage. Twist the insulated V+ and V- wires together and the I+ and I- wires together to further reduce noise pickup.

  • Page 31: Theory Of Operation

    The shunt ammeter consists of six (6) current ranges with six (6) different shunt resistor values ranging from 0.01 Ω to 1111 Ω. Joulescope actively selects the best shunt resistor to keep the maximum voltage across the shunt resistor to 20 mV. This low voltage drop minimizes the impact on the device under test.

  • Page 32: Voltmeter

    Joulescope User Interface (UI) temporarily stores capture data in a circular buffer. The UI allows you to adjust the buffer size to use your host computer’s RAM. Joulescope can also record to a file, and the capture size is only limited by your computer’s available storage on your hard disk drive or solid-state drive.

  • Page 33: High Impedance / Low Leakage

    Joulescope to make accurate and precise low current measurements. 10.6. Electrical isolation The sensor side of Joulescope is electrically isolated from the host computer. This isolation allows you to insert Joulescope into your test system without worrying about ground issues, including ground loops and ground noise.

  • Page 34: How To Swap The Front Panel

    Swapping the panel is easy, but you do need to take proper precautions to avoid damaging your Joulescope. The JS220 can be damaged by static electricity that you don’t even notice. When you expose the Joulescope main board, be sure only to handle it by the board edges. Follow these steps carefully: •...

  • Page 35: Gpi & Gpo

    The Joulescope contains four (4) general-purpose inputs (GPI) and two (2) general-purpose outputs (GPO) located on the GPIO connector to the left of the host USB connecter. The JS220 includes a GPIO cable harness that can simplify connecting the GPIO to target devices and breadboards. The BNC Trigger connector located to the right of the host USB connector can be configured as either an additional general purpose input or output.
  • Page 36 Using Vref also ensures that the outputs do not backpower the device under test. Alternatively, the JS220 can use a internal 3.3V reference voltage. In both cases, Vref determines the output voltage high level. The input threshold voltage is one half of this voltage.

  • Page 37: Electrical Isolation

    13. Electrical Isolation The Joulescope is electrically isolated between the USB interface and the IN/OUT sensor. Joulescope is rated to ±48V between USB ground and any of Current +, Current -, Voltage +, and Voltage -. The individual component ratings far exceed this specification. The components are:...

  • Page 38: Typical Behavior

    Joulescope is a shunt ammeter with incredibly fast autoranging. This section contains typical autoranging measurements. The test setup includes a Joulescope JS220 with the JS220 Evaluation Kit 1 (EVK). For this test, an additional 2200 µF electrolytic capacitor was placed across Voltage + and Voltage – to assist the transient response of the EVK’s low dropout regulator.

  • Page 39: Maintenance

    15. Maintenance The Joulescope JS220 is designed for minimal maintenance. To clean your Joulescope, disconnect all wires from the unit. You can gently wipe the unit with a damp cloth using water only. Using rubbing alcohol or other cleaning agents may damage your Joulescope. Do not submerge.

  • Page 40: Current Validation Process

    During the test process, you should fill in all light-blue cells with measurement data. All TUR values should be green. Yellow indicates that the test setup lacks sufficient accuracy. All “As Measured” values should be green. Red indicates that the Joulescope does not meet specifications. 15.1.3. Current Validation Process The current calibration process can be performed using several methods.
  • Page 41 Numerous valid test equipment methods exist to generate and accurately measure the target current. You may select a method that is appropriate for your equipment. The Joulescope JS220 has a very large current range, and you will need to accurately measure from 18 µA to 3 A. You may need to employ more than one method to cover the entire current range with a sufficient TUR.
  • Page 42 Method 1: Reference current source If you have a reference current source, connect the current source to the Joulescope Current terminals, observing polarity. In step (2), directly configure the reference current source to generate the target current. In step (3), read the applied current from the reference current source.

  • Page 43: Compliance

    Directive 2004/108/EC. In accordance with the European Waste Electrical and Electronic Equipment Directive (WEEE), this device needs to be recycled in accordance with local regulations. Revision 1.3 Joulescope JS220 User’s Guide Page 43 / 51 www.joulescope.com...

  • Page 44: Safety

    16.4. Safety Joulescope is an Extra-Low Voltage device as per IEC 60038. Joulescope is intended for INDOOR USE only. 16.5. RoHS Directive 2011/65/EU, 2015/863/EU This product is CE marked and complies with the European Union’s Directive 2011/65/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 8 June 2011 on the restriction of the use of certain hazardous substances in electrical and electronic equipment.

  • Page 45: Warranty

    Jetperch shall not be liable for loss of use of Joulescope. Jetperch will not be liable for any other incidental or consequential damages, expenses, or financial losses, nor will Jetperch be liable for claims of such damages.

  • Page 46: Intellectual Property

    18. Intellectual Property This product is protected by the following patents: U.S. Patent Number 11,249,117 Additional U.S. Patents Pending Joulescope is a registered US trademark of Jetperch LLC. Revision 1.3 Joulescope JS220 User’s Guide Page 46 / 51 www.joulescope.com...

  • Page 47: Contact

    If you have questions regarding operation of Joulescope, search the website at: https://www.joulescope.com/ And visit the forum: https://forum.joulescope.com/ For compliance information, see https://www.joulescope.com/compliance/js220 If you wish to contact Jetperch regarding the operation of your Joulescope, contact us through email at: support@joulescope.com Location Jetperch LLC 3470 Olney – Laytonsville Rd. Suite 104 Olney, MD 20832-1734 Revision 1.3...

  • Page 48: Glossary

    The quantity of opposition to the flow of electric current. Shunt Ammeter An ammeter that measures the voltage across a resistor, and then uses Ohm’s Law to compute current. Revision 1.3 Joulescope JS220 User’s Guide Page 48 / 51 www.joulescope.com...
  • Page 49 The resistor used by “Shunt Ammeters” to detect current using Ohm’s Law: I = V / R. Given a known R and a measured V, the ammeter computes I. Universal Serial Bus (USB) The now ubiquitous standard for connecting computers and peripherals. Joulescope connects to the host computer using USB 2.0 high-speed operating at 480 Mbps. Voltage The electric potential difference, measured in volts (V).

  • Page 50: User's Guide Information

    21.1. Copyright notice © 2019-2022 Jetperch LLC All material in this Joulescope JS220 User’s Guide, including the text, images, design, and logos, are owned by Jetperch LLC, either through copyright or trademark, unless otherwise indicated. No part of this User’s Guide may be reproduced in any form or by any means without prior written consent from Jetperch LLC as governed by the United States and international copyright laws.
  • Page 51 Edits for clarity. Added step response measured using EVK. Updated Joulescope UI images. 2022 Oct 12 Improved “How to Connect Your Joulescope” section. Thank you to Simon Merrett for providing feedback. 2022 Oct 11 Added connection diagrams. Fixed typos and JS110 references.

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