The NanoRanger NR-01 is an affordable, highly accurate 3.5-digit dc ammeter designed for accurately measuring low currents. With automatic dynamic ranging (9 ranges across 8.5 decades), NanoRanger measures currents from 1 nA up to 800 mA with a maximum resolution of 10 pA. Each instrument is supplied factory calibrated, eliminating the requirement for high-cost precision components in the design, and thus keeping the purchase price low. The current is measured with a 12-bit ADC which is oversampled and automatically averaged to produce a 16-bit result. Samples are taken every 170 μsec. Readings are shown every 300 msec, built up from 180 averaged samples to eliminate line noise (both 50 and 60 Hz). An alternative ‘Fast Sample’ Mode can sample at 150 measurements per second.
The backlit 11-digit 128×64 LCD provides a wealth of information for current readings; for instance, mA, μA, nA, and pA are all on one line. A Running Average reading (current and time elapsed) allows the user to measure power consumption of specific events, such as radio transmissions. The Range Coverage Bar shows the ranges covered during the measurement; it can be ‘bracketed’ or limited to just one range. A signal-to-noise ratio display shows how much noise, or ac, is present on the current signal. Minimum and maximum ranges can be adjusted to limit the auto-ranging, or fixed at a single range.
Challenges arise when trying to measure the power consumption of low power circuits operating in offline or standby mode. Typically, current consumption falls into the nA or pA ranges that are beyond the capability of most DMMs, but the NanoRanger measures accurately into these ranges. A 6.5-digit DMM with 1-nA resolution may only have a lowest range of 2.000000 mA, and the absolute accuracy may only be ±500 nA. The NanoRanger has selectable ranges for every decade of measurement.
NanoRanger is designed with a fully isolated USB interface for device control and data export. Being fully isolated means that a USB connection will not adversely affect the measurements.
Low Burden Voltage (below 0.05 V) on all ranges.
User-configurable Auto Power-off timer.
5.8×3.6×1.2 in; 7 oz
Measure leakage currents over time.
Understand and manage IoT power budgets.
Two AA batteries allow 150 hours of operation
As engineers strive for more efficiency from new and existing products, the measurement of current consumption of devices is becoming more critical. One of the challenges in working with low power analog and digital circuits is the problem of burden voltage – the voltage drop caused by current flowing through a current measuring device that uses an internal shunt resistor network, common in most DMMs. The NanoRanger has been designed specifically to minimize burden voltage to less than 50 mV when taking low power current measurements. A large burden voltage can affect the circuit being measured, corrupting the measurement. For this reason, it is desirable for burden voltage to be kept as low as possible.
NanoRanger is designed by UK-based AltoNovus, which specializes in designing and building low power products. Aimed at the low power development community, including IoT and energy harvesting technologies, NanoRanger is available now from Saelig Company, Inc. For detailed specifications, free technical assistance, or additional information, please contact Saelig at 1-888-7SAELIG, email@example.com, or visit www.saelig.com.