Test Equipment
Power Management

ZS1100A Power Meter

A USB-based power supply that can accurately estimate the energy consumption of IoT devices

$11,474 raised

of $11,000 goal

104% Funded!
Not Available
Jul 23 2020
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Internet of Things is a leading buzzword these days in the technology world. Most of the devices used to create the IoT (Internet of Things) work on small batteries. The measurement of energy consumption of these IoT devices is a difficult task due to the dynamic nature of the current consumption. Developers often need to use multiple instruments and hand calculations to arrive at an estimate of the energy consumption. To solve these problems, the ZS1100A Power Meter has been designed. This tool can plot the current consumption vs time very accurately and in great detail, which can be used along with the battery model to estimate the overall battery life. It has been created by engineers for engineers.

Why do we need another energy meter?

The power consumption of IoT devices follow a peculiar pattern which is difficult to measure using traditional equipment. The main reasons for this are listed below:

ZS1100A IoT power profile measurement

Multimeter: Most multimeters use range switching to achieve high dynamic range. While measuring the current, they introduce series resistor and measure the voltage across it. While measuring μA currents, the multimeter would add a few Ωs (may be kΩs) of resistance in series. If the IoT device performs a wake-up during this state, the drop across the high resistor can cause the device to trip and cause system reset. Most multimeters made for this application can record profiles for only few minutes. An IoT current profile can last several tens of minutes and hence the software on the IoT device may need to be modified to account for the limited capture time. Most multimeters do not have a full function GUI to measure various pulse parameters. The multimeters with digitizer options are expensive with retail costs starting at five thousand dollars, and often significantly higher.

Oscilloscope: Using a scope with a current probe is good enough to measure higher currents in idle and transmission modes. The sleep currents, which are of the order of few μA, cannot be measured with this due to the limited dynamic range. It can either measure high currents or low currents at a time. Most scopes use an 8- to 12-bit ADC and this limits the overall dynamic range. The capture length limits apply to most scopes and the overall solution is very expensive - at least few thousand dollars for the probe and tens of thousands for the scope.

These limitations call for a new approach : ZS1100A Power Meter

Demo Wi-Fi Power Profile

The current profile of an ESP8266 Wi-Fi module is captured here. The module wakes up from sleep using an internal timer and GPIO toggling the RESET pin. The GPIO is captured in the bottom chart. The current rises from 16 μA to few mA in couple of ms. Then it reaches tens of mA and then few hundred mA during the calibration. All of these states are captured in a single range with ZS1100A. This demonstrates the dynamic range, bandwidth, capture length and digital sync feature of the tool. Note how the output voltage remains constant throughout this variation.

Measurement Specifications

Output Voltage Range 0 to 6 V Programmable in 10 mV steps
Output Voltage AccuracyError of 5 mV maxMeasured with 500 mA load
Current Measurement Range -0.5 A to 1.5 A (linear range)
Current Measurement Accuracy1% of measured value ± 0.2 μAAfter one time self calibration
Current Measurement Resolution < 0.1 μA
Max Output Current1 A constant currentVout = 5.0 V
2 A with 10% dutyMeasured with 100 ms pulse for every 1 second
Load Regulation <0.1% 0 to 1.5 A
Measurement Bandwidth300 KHz3 dB bandwidth
Step Response 2 μS 10% to 90% of full range
Current Sampling Rate1 MHz
Sampling Jitter 10 ps RMS jitter
Voltage Sampling RateOnce in every 20 ms
Digital Capture 6 bits at 1 MSPS
Maximum Capture LengthTested up to 24 hrsLimited only by the free space on the HDD
Programmable Output Resistance 0 - 10 Ω In steps of 40 mΩ
Error Rate< 1e-12Less than 1 error in 10^12 samples
Or less than one sample error in 24 hours

Product Specifications


ZS1100A Joulescope™ JS110
Dynamic Range> 123 dB in single range from 1 uA to 1.5 A 196 dB with auto ranging
Maximum Measurement1.5 A 10 A
Resolution< 100 nA (across the range with avg) 1.5 nA to 1 mA depending on range
Accuracy1% ± 200 nA (across full range) ±0.25% ± 30 nA to ±0.3% ±7 mA depending on the range
Sample Rate1 MSPS 2 MSPS
Bandwidth300 KHz 250 KHz
Response Time< 2 μs < 1 μs + Range settling time of up to 5 μs
Data CompressionYes (with option for raw data & different compression strengths) No
Record Size< 1 GB/hr @ 1 MSPS (saves disk space) 30 GB/hr @ 2 MSPS
Max Record LengthUnlimited (> 24 hrs tested) Unlimited
Uses Range SwitchingNo (low distorion) Yes
Includes Power Supply?Yes (0 to 6 V programmable) No
Output Drop< 1 mV at 1 A 23 mV at 1 A
Programmable output resistanceYes (0 to 10 Ω) No
Programmable Current LimitYes N/A (only applicable to power supply)
Noise PerformanceExcellent Excellent
LinearityExcellent Great
Platform CompatibilityWindows only, Linux, macOS are TBD Windows, macOS, and Linux
ScriptingTBD Yes
Protocol AnalysisYes (w/ sigrok) No
USB IsolationPartial (guarantees zero DC ground leakage current) Yes
Thermal ProtectionYes No
Battery EmulationYes (most popular batteries used for IoT) No
Open HardwareYes No
Open SoftwareNo Yes
NIST TraceabilityNo Yes (optional)
Cost (US$)$499 $799


Other solutions use range switching, which can cause load tripping or create high noise. The ZS1100A achieves the high dynamic range using precision analog techniques and Digital Signal Processing.

Joulescope is a registered trademark of Jetperch LLC.

Rev2 prototype

Support & Documentation

We have an online forum at anglercircuits.com where our previous product, ZS2102A, is being discussed. All support, including documentation, user guide, software, drivers, etc. are uploaded here. The same forum shall be used for the ZS1100A. Documentation will also be made available in the project GitHub repository.

Manufacturing Plan

The current plan is to manufacture in India or the United States depending on production volume. A low-volume run would occur in India, while a high-volume run would occur in the United States.

Fulfillment & Logistics

All fulfillment and logistics would be handled by Crowd Supply. ZSCircuits will ship the required quantity of products directly to the Crowd Supply warehouse in the USA. All the backers will get their shipments from Crowd Supply directly. You can learn more about the Crowd Supply fulfillment service in this guide: Ordering, Paying, Shipping: The Details.

Risks & Challenges

On the technical side, we do not foresee any risk as the prototype available in the lab meets the required specifications and level of robustness. We have done extensive testing on these samples to get to this level of confidence level. Three Rev2 units have been tested and they match very well, indicating that there is no variation among units.

The main risk lies in the logistics and supply chain disruption brought about by COVID-19. However, the components used in the designed are widely available across multiple distributors. Hence the risk associated with procurement should be minimal, once the supply chains open up.

A few changes will be made in the Rev4 PCB:

  1. TO-220 sense resistor will be replaced with high power SMD current sense resistor. The TO-220 part was getting obsolete and other options were non-RoHS.
  2. Programmable output resistor circuits will be added.
  3. Blue wiring on the prototype will be fixed.
  4. Current limiting circuit will be added. Simulated and tested on board by blue-wire.
  5. RTC will be added on the I²C bus, which can optionally be used to count the warm-up time.
  6. Over-voltage protection will be added. This is to ensure sudden disconnection of charged inductive loads do not cause a high voltage spike.
  7. Added protection for high reverse current. This sets a limit of 0.5 A going into the power supply.

All of these changes are verified in simulation and pose no impact to the overall schedule. The Rev4 will be manufactured and fully tested in our lab before the final volume build starts. At least three units will be tested for reliability and stability.

Should any unforeseen issues occur during the final testing and/or production, backers will be notified through project updates.

In the Press

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Produced by ZSCircuits in Bangalore, India.

Sold and shipped by Crowd Supply.

ZS1100A Power Meter - Complete Kit

One ZS1100A, along with a power supply, two banana-to-alligator clip cables, eight jumper wires for the front-facing I/O, a USB cable, a flash drive with software, and a quick start guide.

$499 $10 US Shipping / $18 Worldwide

About the Team


Bangalore, India  ·   zscircuits.in

Main area of expertise are Electro-magnetics, RF & Mixed signal board designs, RF test and characterization, Debugging board level problems like spurious emissions, noise coupling analysis, Noise reduction in electronic Systems. In addition we design software and firmware solutions for our products.

Prajay Madhavan

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