# Joulescope JS320 Datasheet The Joulescope™ JS320 is a precision DC energy analyzer. It measures current and voltage, then computes power, energy and charge. It measures current over ten orders of magnitude, from amps down to nanoamps, with fast autoranging and minimal voltage drop. - ±15V voltage range - ±3A current range, continuous - ±10A current pulses (<10 ms, < 3A average per second) - Down to 0.1 nA resolution, equivalent to 36-bits of dynamic range - Synchronously measures voltage and current at 1 million samples per second, 24-bit - 200 kHz linear phase bandwidth - 300 kHz compensated bandwidth with optional digital filter - Rapid 1 μs switching between shunt resistors - Enwavify™ technology for consistent, accurate measurements through current range changes - Computes power, energy, and charge - Operates with minimal voltage disturbance between Current + and Current – ports - Up to ±48V common-mode voltage between USB ground and sensing ports - 4 general-purpose inputs and 2 general-purpose outputs - 1 BNC trigger configurable for either digital input, digital output, or analog output - Programmable on/off for power cycling the target device and measuring inrush currents - USB 2.0 high-speed host connectivity with USB C connector - Host software support for Microsoft® Windows®, Apple® macOS®, and Linux® - Host software user interface provides real-time graphs of current, voltage, and power over time - Python library and scripting provided - Host software is open source and available on GitHub - Swappable front panel with open-source designs on GitHub - Firmware upgradable The [Joulescope JS320 User’s Guide](https://docs.joulescope.com/en/products/js320/guide/index.md) describes how to use the instrument. The specification values are also available as [js320_datasheet.yaml](https://docs.joulescope.com/en/products/js320/js320_datasheet.yaml). ## Absolute maximum ratings | | Min | Max | Unit | |--------------------------------------------------------------------------------------|-----------|-----------|--------| | USB voltage | -0.3 | 6 | V | | Max voltage applied between any port (Current +, Current -, Voltage +, Voltage -) | -20 | 20 | V | | Max voltage to USB ground from any port (Current +, Current -, Voltage +, Voltage -) | -48 | 48 | V | | Input current (powered, burst) | -10 | 10 | A | | Input current (powered, sustained) | -3 | 3 | A | | Input current (unpowered) | N/A (off) | N/A (off) | A | | Storage temperature | -40 | 80 | °C | | Operating temperature | 0 | 50 | °C | | Relative humidity (non-condensing) | 0 | 95 | % | | Altitude from sea level | -100 | 2500 | m | | Max voltage applied to GPI relative to USB ground | -10 | 10 | V | ## Mechanical ### Instrument only | | Typical | Unit | |----------------------------------------------------|-----------|--------| | Weight | 190 | grams | | Width | 99 | mm | | Length (including binding posts and BNC connector) | 126 | mm | | Height | 28 | mm | ### Complete product kit | | Typical | Unit | |--------|-----------|--------| | Weight | 510 | grams | | Width | 190 | mm | | Length | 200 | mm | | Height | 60 | mm | ## Recommended operating conditions | | Test condition | Min | Typical | Max | Unit | |------------------------------------------------|----------------------------------|-----------------|-----------|----------------|--------| | Operating temperature | | 10 | | 40 | °C | | USB supply voltage | | 4.5 | 5 | 5.5 | V | | USB supply current | | | | 500 | mA | | Voltage applied across Voltage + and Voltage - | | -15 | | 15 | V | | Voltage applied across Current + and Current - | Current range off | -15 | | 15 | V | | Input current | continuous | -3 | | 3 | A | | Input current pulse | < 50 milliseconds, < 3A average | -10₁ | | 10₁ | A | | Input current pulse | < 250 milliseconds, < 3A average | -5₁ | | 5₁ | A | 1. Suitable for handling inrush currents when connecting capacitive loads. ## Specification conditions | Temperature | 23 °C ± 10 °C | |----------------------|-------------------------------| | Humidity | 20% to 80% RH, non-condensing | | Calibration interval | 1 year₁ | 1. Recommended to comply with industry-standard practices, but the Joulescope JS320 is designed not to need recalibration. ## Current measurement specifications | Range | Accuracy₁ | Impedance | Guaranteed₂ | |------------------|---------------------------|-------------|--------------------------| | 10 A₃ | ±0.25% ±500 µA | 0.01 Ω | ±10.4 A | | 180 mA | ±0.25% ±50 µA | 0.11 Ω | ±188 mA | | 18 mA | ±0.25% ±5 µA | 1.11 Ω | ±18.8 mA | | 1.8 mA | ±0.25% ±500 nA | 11.1 Ω | ±1.88 mA | | 180 µA | ±0.25% ±50 nA | 111 Ω | ±188 µA | | 18 µA | ±0.25% ±10 nA₄ | 1111 Ω | ±18.8 µA | 1. Accuracy is specified as a percentage of measurement plus a fixed offset. Some instruments specify offset as a percentage of the full-scale range. 2. The highest current that this range is guaranteed to measure without saturation. Higher currents may saturate the range and potentially trip the soft fuse for that current range. 3. Max 3 A sustained. See the recommended operating conditions for higher current durations. 4. ±1.0 nA for ±5 °C over 24 hours with trim offset calibration. The resolution depends on the noise. Noise depends on both the current range and signal bandwidth, which is limited by the sample frequency. The following table shows the typical (not guaranteed) resolution given only the JS320 self-noise with no additional external noise pickup. | Range | 1 Msps resolution (typical) | 10 ksps resolution (typical) | 10 sps resolution (typical) | Units | |---------|-------------------------------|--------------------------------|-------------------------------|---------| | 10 A | 1000 | 100 | 10 | µA | | 180 mA | 100 | 10 | 1 | µA | | 18 mA | 10 | 1 | 0.1 | µA | | 1.8 mA | 1000 | 100 | 10 | nA | | 180 µA | 100 | 10 | 1 | nA | | 18 µA | 10 | 1 | 0.1 | nA | Test current measurement bandwidth by varying the effective load impedance. Due to load capacitance, altering the source voltage is often not a valid method of testing current bandwidth. The JS320 is sensitive to RF radiation, which induces real current in test setups. When tested with EN61326-1 and 3 V RMS/m, the JS320 measured up to 10 µA (observed, not guaranteed) of current at several frequencies. The exact frequency susceptibility varies with cable length and configuration. ## Voltage measurement specifications | Range | Accuracy₁ | Guaranteed | |---------|------------------------|--------------| | 15 V | ±0.1% ±500 µV | ±15.5 V | | 2 V | ±0.1% ±200 µV | ±2.05 V | 1. At V+ == I+. See the CMRR specification for extended voltage. The resolution depends on the noise. Noise depends on both the current range and signal bandwidth, which is limited by the sample frequency. The following table shows the typical (not guaranteed) resolution given only the JS320 self-noise with no additional external noise pickup. | Range | 1 Msps resolution (typical) | 10 ksps resolution (typical) | 10 sps resolution (typical) | Units | |---------|-------------------------------|--------------------------------|-------------------------------|---------| | 15 V | 500 | 50 | 10 | µV | | 2 V | 100 | 10 | 2 | µV | The JS320 is sensitive to RF radiation, which induces real voltages in test setups. When tested with EN61326-1 and 3 V RMS/m, the JS320 error increased by 10 mV (observed, not guaranteed) at several frequencies. The exact frequency susceptibility varies with cable length and configuration. ## General specifications | | Test condition | Min | Typical | Max | Unit | |-----------------------------|------------------|-------|-----------|-------|--------| | Sampling frequency | 25 °C | | 1000000 | | sps | | Sampling frequency accuracy | 25 °C | -5 | | 5 | ppm | | Measurement bandwidth | -3 dB | 185 | 195 | 225 | kHz | | Compensated bandwidth | -3 dB | 280 | 300 | 350 | kHz | | Front panel insertions | | | | 100 | | ## Parasitic effects specifications | | Test condition | Min | Typical | Max | Unit | |-----------------------------------------------------|--------------------------------|-------|-----------|-------|--------| | Current leakage (Voltage + to -) | 25 °C, ±3.3V | | 100 | | pA | | Current leakage (Voltage + to -) | 25 °C, ±5V | | 100 | | pA | | Current leakage (Voltage + to -) | 25 °C, ±15V | | 100 | | pA | | Shunt resistor voltage, max | -2 to 2 A, static | | 20 | 21 | mV | | Burden voltage (Current + to -) | 1 A, banana jacks | 0 | 25 | 35 | mV | | Burden voltage (Current + to -) | Shunt resistor, < ±2 A | | | ±20 | mV | | Shunt switching time | Over-range, < 200 ns rise time | 0 | 0.8 | 1.2 | µs | | Measurement gap following a current range switch | | | | 0 | µs | | CMRR on voltage input (common mode rejection ratio) | 25 °C, ±15V | | -70 | | dB | ## Software-controlled fuse specifications | | Test condition | Min | Typical | Max | Unit | |----------------------------------|------------------|-------|-----------|-------|--------| | Current leakage (Current + to -) | 25 °C, 3.3V | | ±5 | | nA | | Current leakage (Current + to -) | 25 °C, 5V | | ±7 | | nA | | Current leakage (Current + to -) | 25 °C, 15V | | ±28 | ±5000 | nA | | Fuse engage time | 5 A | | 0.293 | | s | | Fuse engage time | 10 A | | 0.050 | | s | ## General purpose inputs and outputs | | Test condition | Min | Typical | Max | Unit | |---------------------------|-----------------------|------------|-----------|------------|--------| | Internal 3.3V reference | | 3.135 | 3.3 | 3.465 | V | | External reference | Vref < (VUSB - 0.5 V) | Vref - 0.1 | Vref | Vref + 0.1 | V | | Input leakage per pin | 25 °C | | | ±10 | nA | | Input leakage per pin | | | | ±100 | nA | | Output voltage high | -100 µA | Vcco - 0.1 | | | V | | Output impedance | 10 mA | 45 | 50 | 80 | Ω | | GPI sample rate | | | 1 | | MSPS | | Continuous output current | Per pin | | | ±50 | mA | | Total power dissipation | Over output impedance | | | 0.25 | W | The Joulescope uses the TI [TLV9034](https://www.ti.com/product/TLV9034) for GPIs and the TI [SN74LVC2T45](https://www.ti.com/product/SN74LVC2T45) to drive the GPOs. Both the GPIs and GPOs are protected with the TI [TPD4E1U06](https://www.ti.com/product/TPD4E1U06) for ESD protection. Both gates of the TI SN74LVC2G125 drive the trigger in parallel, each through a 100 Ω resistor for 50 Ω drive.