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Otii Arc

We love the Otii Arc! It is a truly versatile power supply and analyzer. Coupled with powerful but easy-to-use software, it is an ideal tool to help study the power draw of your IoT project or device. It can record and display real-time currents, voltages and/or UART logs. It provides nanoamp resolution current measurements with a sample rate of up to 4000 samples per second!

Otii (pronounced like naughty) is handy in all sorts of troubleshooting situations. The Otii truly shines with any device that needs to be designed to sleep for low power and has to run 'a long time' on a battery. The Otii Arc can measure current very accurately over eight orders of magnitude from tens of nanoamps up to 5 Amps. This means you can measure the sleep current of a board and the peak current draw all in one continuous measurement. Leave the system logging for hours then read the minimum, maximum and average current and power use straight from the oscilloscope-like recording. By linking the Otii Arc to a UART (Serial) pin and/or a GPIO pin, you can immediately see what the current draw was while the code was performing a specific task. Stop guesstimating what your runtime will be and prove it!

One of the features we really love is that you can connect a battery to the Otii Arc. The Otii Arc can then discharge the battery while recording the voltage and current profile. The Otii Arc can then emulate that same battery, time and time again, saving you the trouble of having to replace or recharge the battery between tests. Want to see how your board will perform when connected to a particular LiPo battery? The Otii Arc lets you do exactly that. (Battery discharge, profiling and emulation requires an additional Otii Battery Toolbox license.)

The Otii Arc has a USB interface to connect to your laptop or computer. It can use USB as its main power source and deliver up to 4.2V to the board under test. Maximum current depends on the USB port but usually between 250mA and 750mA. Connect an external power supply (7.5 - 9 V) and Otii Arc can deliver up to 5.0V at 2.5A continuous, 5A peak! The accompanying software is available for Windows (7 & 10, 64-bit), macOS (High Sierra or later) and Ubuntu (18.04 or later, Intel 64-bit).

  • USB cable (1m)
  • The Otii Arc can be powered over USB (250mA max) but does not come with an external power supply
    • 7.5 - 9VDC (2A+ recommended)
    • 2.1 / 5.5mm barrel jack, +ve center
  • USB Power Supply
    • Output voltage (auto range): 0.5V - 3.75V
    • Output voltage (locked to high current range): 0.5V - 4.2V
    • Output voltage setting resolution: 1mV
    • Output current: 250-750mA (capacity in laptops and desktops greatly depend on host USB port/cable design)

  • External 7.5 – 9V Power Supply
    • Output voltage (auto range): 0.5V - 4.55V
    • Output voltage (locked to high current range): 0.5V - 5.0V
    • Output voltage setting resolution: 1mV
    • Output current (max continuous): 2.5A
    • Output current (max peak): 5A

  • Programmable Current Sink (requires an Otii Battery Toolbox license)
    • Sink current: 0A - 2.5A
    • Sink current resolution: 39µA
    • Sink voltage (USB power supply): 0.85V - 4.2V
    • Sink voltage (external power supply): 0.85V - 5.0V

  • Current measurement
    • Accuracy: ±(0.1% + 50 nA)
    • Sample Rate in ±19 mA range: 4ksps
    • Sample Rate in ±2.7 A range: 1ksps
    • Sample Rate in ±5.0 A range: 1ksps
    • Analog bandwidth (3 dB): 400Hz

  • Voltage measurement
    • Total accuracy: ±(0.1% + 1.5 mV)
    • Sample Rate: 1ksps

  • UART
    • Bitrate: 110bps - 5.25Mbps

  • Digital I/O; GPO1, GPO2, TX
    • VIO Expansion port operating voltage: 1.2V - 5V
    • VIL Low-level input voltage: VIO * 0.2V
    • VIH High-level input voltage: VIO * 0.8V
    • Imax Maximum sink/source current: 10 mA

Otii Arc Product Help and Resources

Core Skill: Programming

If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.

3 Programming

Skill Level: Competent - The toolchain for programming is a bit more complex and will examples may not be explicitly provided for you. You will be required to have a fundamental knowledge of programming and be required to provide your own code. You may need to modify existing libraries or code to work with your specific hardware. Sensor and hardware interfaces will be SPI or I2C.
See all skill levels

Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

4 Electrical Prototyping

Skill Level: Experienced - You will need to consult a datasheet for calculations to determine a components output format, linearity, and do a little math to get what you need. You will be using a datasheet or schematic beyond basic pinouts.
See all skill levels


Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • DAS01 / about 3 years ago / 1

    This is a really great product. I have owned one of these for a couple of years now. Battery emulation is one thing that sets this apart from many other power supplies. I would recommend buying the external power supply for it as with the USB it is a little light-weight.

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