Whether you are designing a battery-powered smart home sensor or a DIY handheld computing platform, minimizing energy use is essential for a good user experience. But before you can reduce power consumption, you first need to measure it. That can be tricky to do at home when dealing with microcontroller sleep states, for instance, where current draw is often measured in nanoamps. The precision equipment needed to reliably measure current at this scale can be quite expensive.
A new high-speed, auto-ranging precision current adapter for multimeters and oscilloscopes called TopCurrent was designed to make this capability more accessible. It does this by transforming standard voltage-measuring instruments into highly accurate current analyzers. Instead of requiring specialized equipment, the device converts input current into a proportional voltage output, with a simple 1 mV per-unit scaling depending on the active range. This allows users to leverage existing multimeters or oscilloscopes while achieving precision typically reserved for far more expensive systems.
A look at the inputs and outputs (📷: Hexed)
TopCurrent has the ability to measure across an exceptionally wide range—from as low as 1 nanoamp up to 3 amps—spanning orders of magnitude. It accomplishes this with three automatically selected ranges (nA, µA, and mA), eliminating the need for manual adjustments. The device also offers rapid range switching, with upward transitions occurring in under 2.5 microseconds, enabling accurate capture of fast-changing current profiles such as those seen in wireless transmissions or processor wake cycles.
Despite its speed, TopCurrent maintains a very low burden voltage—typically just microvolts per unit of current, and no more than 20 millivolts even during switching. This is critical for ensuring that the measurement process itself does not significantly alter the behavior of the circuit under test, a common issue in low-current analysis.
The system operates without firmware, microcontrollers, or ADCs, relying instead on analog design techniques to achieve its performance. This simplifies operation and improves reliability, while also appealing to users who prefer transparent, hardware-based solutions.
The internal hardware (📷: Hexed)
The device is housed in an aluminum enclosure with grounded PCB panels, forming a partial Faraday cage to reduce electrical noise. For connectivity, it includes both banana jacks and a BNC output, making it compatible with a wide range of lab equipment. Additional flexibility is provided through expansion space inside the enclosure, allowing users to integrate custom add-ons such as displays or microcontroller-based logging systems.
TopCurrent is an open source friendly project, with plans to release design files and schematics publicly. This could enable further innovation and customization by the community, from noise filtering enhancements to faster switching optimizations.
The device will be launching soon on Crowd Supply, and you can sign up for notifications to stay in the loop.
