SDAA132 December   2025 MSPM33C321A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 MSPM33C Hardware Design Check List
  5. 2 Power Supplies in MSPM33C Devices
    1. 2.1 Digital Power Supply
    2. 2.2 Analog Power Supply
    3. 2.3 Built-in Power Supply and Voltage Reference
    4. 2.4 Recommended Decoupling Circuit for Power Supply
    5. 2.5 Recommended Decoupling Circuit for VBAT
  6. 3 Reset and Power Supply Supervisor
    1. 3.1 Digital Power Supply
    2. 3.2 Power Supply Supervisor
  7. 4 Clock System
    1. 4.1 Internal Oscillators
    2. 4.2 External Oscillators
    3. 4.3 External Clock Output (CLK_OUT)
    4. 4.4 Frequency Clock Counter (FCC)
  8. 5 Debugger
    1. 5.1 Debug Port Pins and Pinout
    2. 5.2 Debug Port Connection With Standard JTAG Connector
  9. 6 Key Analog Peripherals
    1. 6.1 ADC Design Considerations
    2. 6.2 COMP Design Considerations
  10. 7 Key Digital Peripherals
    1. 7.1 Timer Resources and Design Considerations
    2. 7.2 UART and LIN Resources and Design Considerations
    3. 7.3 MCAN Design Considerations
    4. 7.4 I2C and SPI Design Considerations
    5. 7.5 I2S/TDM Design Considerations
    6. 7.6 QSPI Design Considerations
  11. 8 GPIOs
    1. 8.1 GPIO Output Switching Speed and Load Capacitance
    2. 8.2 GPIO Current Sink and Source
    3. 8.3 High-Speed GPIOs (HSIO)
    4. 8.4 High-Drive GPIOs (HDIO)
    5. 8.5 Communicate With a 1.8V Device Without a Level Shifter
    6. 8.6 Unused Pins Connection
  12. 9 Layout Guides
    1. 9.1 Power Supply Layout
    2. 9.2 Considerations for Ground Layout
    3. 9.3 Traces, Vias, and Other PCB Components
    4. 9.4 How to Select Board Layers and Recommended Stack-up
  13. 10Bootloader
    1. 10.1 Bootloader Introduction
    2. 10.2 Bootloader Hardware Design Considerations
      1. 10.2.1 Physical Communication interfaces
      2. 10.2.2 Hardware Invocation
  14. 11Summary
  15. 12References

8.5 Communicate With a 1.8V Device Without a Level Shifter

The MSPM33C series devices use a 3.3V logic level . If users need to communicate with 1.8V devices and do not use external level shifter devices, Figure 8-1 shows a suggested circuit for interfacing with a 1.8V device.

Suggested Communication Circuit With 1.8V Device Figure 8-1 Suggested Communication Circuit With 1.8V Device

Two MOSFET are used in this circuit. Check the VGS to make sure this MOSFET can fully turn on with a low RDS(on). For a 1.8V device, use less than 1.8V VGS MOSFET. However, a too low VGS MOSFET can cause the MOSFET to turn on at a very small voltage (MCU logic judges as 0), resulting in a communication logic error.

U1 output and U2 input

  1. U1 output 1.8v high, Q1 VGS around 0, thus Q1 turn off, U2 reads 3.3v high with R4.
  2. U1 output low, Q1 VGS around 1.8v, thus Q1 turn on, U2 reads low.

U1 input and U2 Output

  1. If the U2 output is 3.3V high, then keep U1 at 1.8V with R1, and Q1 turn off, thus U1 reads 1.8V high.
  2. If the U2 output is low, then keep U1 at 1.8V with R1. But the diode inside MOSFET pulls down U1 to 0.7V (diode voltage drops) and causes VGS to be greater than the turn-on voltage; Q1 turns on, and U1 reads low.