SNVAA92 November   2023 LM63625-Q1 , TPS37-Q1 , TPS3703-Q1 , TPS3850-Q1

 

  1.   1
  2.   Abstract
  3. 1Introduction
  4. 2Power Designs for Safety MCUs With Functional Safety Requirements
  5. 3ASIL B Power-Supply Design Example and FMEDA Analysis
    1. 3.1 Functional Safety Requirements
    2. 3.2 Proposed Power Design
    3. 3.3 FMD and Pin FMA
    4. 3.4 LM63625-Q1 and TPS37A-Q1 FMEDA Analysis at the Die Level
    5. 3.5 LM63625-Q1 and TPS37A-Q1 FMEDA Analysis at the Pin Level
      1.      11
    6. 3.6 Total FMEDA Analysis of the LM63625-Q1 and TPS37A-Q1
  6. 4Summary
  7. 5Additional Resources

3.2 Proposed Power Design

Figure 3-4 adopts the design shown in Figure 3-4, redrawing the diagram and including the part number for the regulator.


GUID-20231108-SS0I-PMHL-CZKW-WPHCWJK2N0SV-low.svg

Figure 3-1 Power-Supply Design for an MCU to Meet ASIL B Criteria

The LM63625-Q1 is a 3.5-V to 36-V wide-VIN buck converter; the power output is 3.3 V. The safety operating voltage of the MCU is from 3 V to 5 V. The TPS37A-Q1 monitors the 3.3-V power-supply output, and resets the safety MCU when the voltage is above 5 V or below 3 V. The TPS37A-Q1 therefore implements an over- and undervoltage detection safety mechanism (SM).