The Joulescope JS220 is a precision DC energy analyzer designed for measuring current, voltage, power, charge, and energy consumption in a wide range of devices, particularly those with high dynamic current ranges like modern battery-powered and IoT devices. It excels at measuring from nanoamps (nA) to amps (A), even when devices rapidly switch between sleep and active modes.
Function Description:
The JS220 functions as a combined voltmeter and a fast auto-range current shunt ammeter. It simultaneously measures current and voltage at 2 million samples per second with 300 kHz bandwidth. From these measurements, it computes power, energy, and charge. Its primary purpose is to enable engineers to accurately profile and optimize power consumption in microprocessors, microcontrollers, and other hardware, troubleshoot hardware and software, characterize software, and perform USB inrush and suspend current pre-compliance testing. The device is designed to provide rapid feedback on how design changes affect battery life.
Important Technical Specifications:
- Voltage Range: ±15V
- Current Range: ±3A continuous, ±10A current pulses (<10 ms, < 3A average per second)
- Current Resolution: Down to 0.5 nA, equivalent to 34-bits of dynamic range
- Sampling Rate: 2 million samples per second (SPS)
- Bandwidth: 300 kHz
- Voltage Drop (Burden Voltage): 25 mV at 1 A (typical), with rapid 1 µs switching between shunt resistors to maintain low voltage drop.
- Common-mode Voltage: Up to ±48V between USB ground and sensing ports
- General Purpose Inputs/Outputs (GPIO): 4 general-purpose inputs, 2 general-purpose outputs
- Trigger: 1 BNC trigger configurable for either input or output
- Connectivity: USB 2.0 high-speed with modern USB C connector
- Operating Temperature: 0 to 50 °C
- Storage Temperature: -40 to 80 °C
- Relative Humidity (non-condensing): 0 to 95%
- Altitude from sea level: -100 to 2500 m
- Weight (Instrument Only): 190 grams
- Dimensions (Instrument Only, including binding posts and BNC connector): 99 mm (width) x 126 mm (length) x 28 mm (height)
- Electrical Isolation: Rated to ±48V between USB interface and IN/OUT sensor.
Current Measurement Specifications (Accuracy and Resolution):
- 10 A Range: ±0.25% ±1.50 mA accuracy, 175 µA resolution, 0.01 Ω impedance
- 180 mA Range: ±0.25% ±150 µA accuracy, 15 µA resolution, 0.11 Ω impedance
- 18 mA Range: ±0.25% ±15 µA accuracy, 1.5 µA resolution, 1.11 Ω impedance
- 1.8 mA Range: ±0.25% ±1.5 µA accuracy, 150 nA resolution, 11.1 Ω impedance
- 180 µA Range: ±0.25% ±150 nA accuracy, 15 nA resolution, 111 Ω impedance
- 18 µA Range: ±0.25% ±30 nA accuracy, 1.5 nA resolution, 1111 Ω impedance
Voltage Measurement Specifications (Accuracy and Resolution):
- 15 V Range: ±0.1% ±10 mV accuracy, 1.2 mV resolution
- 2 V Range: ±0.1% ±2 mV accuracy, 180 µV resolution
Usage Features:
- Dynamic Range: Accurately measures current over ten orders of magnitude, crucial for modern devices with varying power states.
- Low Voltage Drop: Minimizes the impact on the device under test, ensuring accurate measurements without altering the device's behavior.
- High Sampling Rate: Captures short events like interrupt service routines and inrush currents, making "the invisible visible."
- User-Friendly Software: The host software provides both a multimeter view for quick summaries of instantaneous voltage, current, power, and energy, and an oscilloscope view for exploring dynamic behavior and troubleshooting.
- Multimeter View: Displays mean, standard deviation (σ), minimum (min), maximum (max), and peak-to-peak (p2p) values for current, voltage, and power. Energy and charge are displayed as cumulative values.
- Oscilloscope View: Shows waveforms of voltage and current over time, allowing for detailed analysis of transient events. Features include:
- Current Range Selection: Automatic or manual selection of the best shunt resistor.
- Voltage Range Selection: Automatic or manual selection between 15V and 2V ranges.
- Accumulators: Displays accumulated energy or charge, which can be reset.
- Annotations: Supports single and dual markers for statistical analysis over selected time ranges, including mean, standard deviation, min, max, p2p, and cumulative energy/charge.
- Zoom and Pan: Allows detailed inspection of waveforms.
- Y-axis Scaling: Supports linear and logarithmic scales for viewing wide dynamic ranges.
- Signal Display: Users can select which signals (current, voltage, power, current_range, in0, in1) to display.
- Open-Source and Customizable: The host software is open source (Python 3.8+) and available on GitHub, allowing for custom scripting and integration into applications. The front panel is also swappable with open-source designs available on GitHub, offering flexibility for different connector types.
- Portable: Compact form factor fits in a backpack and requires minimal desk space.
- Kelvin-Connection Measurements: Specifically designed for more accurate 4-wire Kelvin-connection measurements to exclude voltage drop in wires from target consumption measurements.
- Power Cycling: Programmable on/off for power cycling the target device and measuring inrush currents.
- Enwavify™ Technology: Ensures consistent, accurate measurements through current range changes.
Maintenance Features:
- Minimal Maintenance: Designed for minimal upkeep.
- Cleaning: Can be gently wiped with a damp cloth (water only) after disconnecting all wires. Avoid rubbing alcohol or other cleaning agents. Do not submerge.
- Factory Calibrated: Joulescope JS220 units are factory calibrated and designed to maintain specifications throughout their operating life.
- Recalibration: For critical applications, annual recalibration by authorized providers (Jetperch LLC or Tra-Cal) is recommended, although the device is designed not to require it.
- Firmware Upgradable: Ensures the device can be updated with the latest features and improvements.
- Verification Procedure: A detailed procedure is provided for verifying the instrument's operation against specifications using a calibrator and a validation spreadsheet.
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