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Safety Analysis — Vitachrona MIPI Wearable
Status
Draft — schematic-stage safety architecture assessment.
Primary Hazard Areas

Table

HazardSourceInitial Mitigation Direction
Patient leakage currentECG/bioimpedance electrodes, charger/debug interfacesDefine applied-part strategy; consider battery-only sensing and disable measurements during charging until proven safe.
Skin burn / thermal injuryLiPo pack, Qi coil, LTE bursts, display/backlight, regulatorsAdd NTC monitoring, thermal shutdown policy, charge-current limits, enclosure thermal validation.
Battery fire/swellingLiPo charger/protection faultsValidate BQ25895, protection IC, NTC, current limits, short-circuit protection, UN38.3/IEC62133 cell documentation.
Measurement corruptionLTE/GNSS bursts, MIPI DSI, Qi magnetic field, switching regulatorsPartition analogue/RF/power regions; add filtering, shielding, quiet rails, firmware state gating.
Overcurrent into bodyAD5940 bioimpedance excitation faultSet excitation limits, protection network, single-fault analysis, firmware limit checks.
False medical display/alertFirmware, display, sensors, wireless linkDefine claims, alarm behavior, verification plan, watchdog/failsafe strategy.
Safety-Critical Subsystems
  • ADS1299 ECG front end.
  • AD5940 bioimpedance/electrochemical front end.
  • MAX86176 biometric front end and VEMD8080 optical detector.
  • LiPo charger/protection/fuel gauge/regulators.
  • BQ51013B Qi wireless receiver and coil interface.
  • SARA-R510M8S-00B cellular/GNSS module and antennas.
Required Decisions Before Schematic Freeze
  1. Medical vs wellness claim boundary.
  2. Charging while worn: allowed or prohibited.
  3. Patient-connected sensing while charging: allowed or disabled.
  4. Applied-part classification target, if medical: BF/CF assumption.
  5. Conductive external contacts and ingress/sweat exposure strategy.
  6. Maximum skin-contact temperature limit.
Open Validation Items
  • MAX86176 public-vs-NDA boundary: only public power/digital support is implemented. J22 optical, J20 ECG/RLD, and J23 reference nets are explicitly AFE_MODULE_TBD. No patient-connected or optical-drive analogue network may be populated until NDA-controlled application data, optical/mechanical design, current limits, leakage, and single-fault review are approved.
  • Datasheet-backed support circuits for all safety-critical ICs.
  • Full power budget and thermal budget.
  • Leakage-current and single-fault safety analysis.
  • EMC pre-compliance plan.

  • Status

  • Primary Hazard Areas

  • Safety-Critical Subsystems

  • Required Decisions Before Schematic Freeze

  • Open Validation Items