TinyCurrent Ultra-Low Electrical Current Measurement Probe

The TinyCurrent by n-Fuse is a probe to accurately measure ultra-low currents in the micro-Amp (uA) and nano-Amp (nA) scale. It was specifically designed for measuring varying currents on today’s low-power devices.
It converts the current to an amplified voltage that can easily be measured and displayed as a DC or AC voltage on a multimeter or oscilloscope. It can measure changing currents up to 300kHz. Because the voltage is buffered and amplified it overcomes the issue of high burden voltage as seen with multimeters and it enables low current measurement with an oscilloscope.
Switch-mode voltage regulators and the varying current draw of MCUs and RF chips require the determination of the current draw over time to calculate the total power consumption of a device. An oscilloscope is a perfect tool for this task and is widely available. For this reason, the TinyCurrent features a BNC connector to reduce the picked-up noise while measuring with an oscilloscope.
In addition to the internal battery, which comes with the benefit of a floating ground, the TinyCurrent can also be powered from an external power source up to 5.5V. This gives it an increased dynamic range for measuring current over a wider range.

The TinyCurrent is based on the original Open Source uCurrent design by EEBVlog, and with Dave’s knowledge. Here are the modifications that were made to the original design:
Added BNC output for even lower noise when acquiring with a high sampling rate-high input impedance instruments like an oscilloscope. The effect is lower noise compared to normal banana leads.
Added a 2-pin 1.25 mm JST ZH style male header for powering the device externally to better use the device in permanent measurement setups. Only use without a battery.
Allow the device to be fed with a supply voltage of up to 5.5 V to increase the dynamic range (only when an external power source is used).
Added header J6 which allows for installation of a THT resistor or bond wire to change the ratio of the voltage divider R6/R7 to increase the dynamic range for positive currents. R6/R7 have a ratio of 1/5 to allow for a maximum positive output voltage of ~80% of the supply voltage.
“R-Variant” with a reversed BNC connector optimized for attaching the device directly to an oscilloscope’s input via a BNC-to-BNC adapter.

Specifications:

• Min/Max Current Range @ 2.9V VDD:
• nA: 1250 nA (20 V / nA burden voltage typical), contact resistance plays a role here. 10 V due to the shunt resistor
• A: 1250 A (10 V / A burden voltage)
• mA: 1250 mA (10 V / mA burden voltage)
• Min/Max Current Range @ 5.5V VDD (from an external power source):
• nA: 2550 nA (20 V / nA burden voltage typical), contact resistance plays a role here. 10 V due to the shunt resistor.
• A: 2550 A (10 V / A burden voltage)
• mA: 2550 mA (10 V / mA burden voltage)
  Resolution in nA Range:
• 1000 pA on a 3.5 digit DMM
• 100 pA on 4.5 digit DMM
• 10 pA 5.5 digit DMM
• Accuracy: < 0.05% on A and nA ranges; < 0.1% on mA range
• Output Offset Voltage, maximum: < 30 V
• Temperature Drift: < 10 ppm/deg C ( A / nA); < 15 ppm/deg C (mA)
• Noise: < -90 dBV
• THD: < -60 dB
• Bandwidth (-3dB): 300 kHz
• Maximum Supply Voltage: 5.5 V
• Maximum Current through input ports: 5A
• To keep the burden voltage low, this device has no OVERLOAD PROTECTION. That means NO FUSES. Care is required in using the unit to prevent damage.
• Size: 85 x 55 x 50mm, 199g
• Battery: CR2032 Lithium coin cell or max 5.5 V through connector J5 (battery not included)
• CE Certified

What’s in the box
1 x TinyCurrent PCB in Case, User Manual