Summary

Jason Sachs explains why off-state leakage in analog switches can corrupt sensor readings and drain batteries, and how to quantify and mitigate those effects in embedded designs. The blog covers relevant datasheet parameters, hardware and firmware workarounds, and practical test methods for real boards and operating temperatures.

Key Takeaways

• Measure the off-state leakage and include it in accuracy and power budgets for ADC and high-impedance inputs.
• Choose switches by comparing datasheet leakage, temperature behavior, on-resistance, and charge-injection specs rather than just price.
• Design hardware mitigations: use series resistors, input buffers, guard rings, and proper power sequencing to isolate high-impedance nodes.
• Implement firmware mitigations: add settle delays, active drive/aggregation during conversions, and calibration routines to compensate leakage.
• Verify designs on real PCBs across temperature and humidity to catch layout- and environment-driven leakage paths.

Who Should Read This

Intermediate embedded hardware and firmware engineers designing sensor front-ends, low-power IoT devices, or ADC-based measurement systems who need to avoid measurement errors and unexpected power drain.

Still RelevantIntermediate

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