Summary

Jason Sachs revisits the practical problem of selecting and implementing slew rate limits for current waveforms, re-evaluating conclusions from an earlier 2014 article. The blog explains trade-offs between waveform fidelity, EMI, control stability, and implementation choices (analog vs digital), and gives rules of thumb and test methods engineers can apply.

Key Takeaways

• Compute the required slew rate from desired rise/fall times and the system’s bandwidth to ensure waveform and control-loop compatibility.
• Choose between analog and digital implementations based on latency, resolution, and quantization—use analog for lowest latency, firmware for flexibility.
• Mitigate EMI and power-stage stress by matching slew limits to driver/board bandwidth and by controlling dV/dt and dI/dt across the system.
• Implement anti-windup and saturation handling in control loops when applying slew limits to prevent instability or integrator windup.
• Validate designs with time-domain step tests and spectral (FFT) measurements, and iterate limits based on real-world driver and sensor behavior.

Who Should Read This

Embedded hardware and firmware engineers (intermediate level) who design current-driving circuits, motor controllers, or power electronics and need practical guidance on choosing and validating slew-rate limits.

Still RelevantIntermediate

Topics