Current Sense Design Tool
Design your Current Sense Solution with ease
The onsemi tool guides you to the right onsemi products while optimizing performance and efficiency.
The Current Sense tool includes onsemi’s Current Sense Amplifiers
Workflow
Current‑sense design tool streamlines the normally iterative process by guiding you through system inputs, component selection, and performance evaluation to quickly create an optimized shunt‑based sensing solution.
Inputs Page
The input page collects key system requirements such as supply voltage, common ‑ mode range, current limits, reference settings, and expected amplifier temperature. These inputs guide device recommendations, account for bidirectional or unidirectional current sensing, and incorporate shunt power, tolerance, and temperature‑coefficient assumptions. The tool includes optional input‑filter resistor and tolerance effects—adding gain, offset, and temperature‑related errors—while noting that transient behavior is not modeled. After entering all parameters, you can submit the data to move to the Design Worksheet, refine the solution, save designs, or reset to defaults.
Design Worksheet Page
Once you submit the inputs, a part-selection window appears showing recommended amplifiers, gain options, packages, and links to datasheets. After choosing a device, the Desing Worksheet provides visual feedback, such Nominal output voltage with worst‑case upper and lower boundaries and provides warning when output limits are exceeded.
Error Curves
In addition, design worksheet provides two complementary views of DC error performance showing how accurate the system is and how much current can actually be trusted across the operating range.
Design Summary
The Design summary page shows Design Specifications, Shunt Characteristics, Designs results and the selected amplifier part specifications along with the schematic and error curves.
Printing this page formats well in a PDF letter format.
Current Sense Design Tool FAQ
The tool streamlines the normally iterative process of designing a shunt‑based current sense solution. It evaluates amplifier datasheet parameters, shunt characteristics, and system requirements to estimate accuracy, power loss, and performance across load conditions.
The tool incorporates extreme-value min/max specifications from the amplifier including:
- Gain error
- Offset voltage and drift
- CMRR
- PSRR
- Input bias/offset currents
- Nonlinearity
- Temperature effects
- Input filter resistor effects
You must provide:
- Supply voltage (VS)
- Maximum input common-mode voltage
- Full-scale positive and negative current
- Zero-current reference voltage (VREF) and tolerance
- Operating temperature range
- Input filter resistor value and tolerance
- Maximum shunt power
- Shunt tolerance and temperature coefficient
- Desired light-load and full-load accuracy
The tool uses these to recommend shunt values and compatible devices.
The tool models the impact of input filter resistors on:
- Gain reduction
- Added error due to resistor tolerance
- Temperature mismatch between filter resistors and amplifier input impedance
- It does not calculate filter response or suggest filter capacitance as this is a purely DC accuracy calculator
Based on:
- Full-scale current
- Maximum allowable shunt power
- Accuracy requirements
The tool selects a shunt value that fits within the power budget while maximizing accuracy. One of the most important selections is the shunt power requirement.
No. The tool is a DC error calculator and does not model:
- Differential or common-mode transients
- Fast switching noise
- Dynamic response
After submitting system inputs:
- A Part Selection window appears.
- The tool recommends devices based on gain, polarity, and operating conditions.
- You choose a device and proceed to the Design Worksheet.
Each recommended part includes gain, package, and a link to its datasheet.
You can modify:
- Shunt resistance, tolerance, and tempco
- Selected amplifier gain
- System parameters (VS, VREF, currents, etc.)
The worksheet also provides:
- A schematic
- Pinout options
- Export/import functionality
- Real-time error and performance curves
Three key curves help validate the design:
- Output Voltage vs. Load Current Shows nominal output and worst-case output operational boundaries.
- Output Error Current vs. Load Current expressed in amps (the current value that the circuit can resolve)
- Output Accuracy vs. Load Current (%)
Examples include:
- VFS > VOUT Max — full-scale output exceeds amplifier limits
- Scale Utilization > 100% — output range is overdriven
- Output Voltage Range errors — min/max output outside device specs
You can:
- Reduce shunt resistance
- Lower gain
- Adjust VREF
- Revaluate full-scale current range
Yes. The tool supports:
- Exporting a design file from the worksheet
- Importing it on either the Inputs or Worksheet page
No. It highlights out-of-spec results in red, but still allows you to evaluate them.
Temperature impacts:
- Offset drift
- Gain drift
- Shunt tempco
- Filter resistor mismatch
The tool uses amplifier datasheet min/max drift values to compute worst-case error.
Scale Utilization (%) = How much of the amplifier’s output range (GND to VS) is used at full-scale current.
Values above 100% indicate clipping or invalid output