SLLA643 August   2024 MCF8315C , MCF8315C-Q1 , MCF8316C-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Power Pin Design Recommendations
    1. 2.1 VM
    2. 2.2 Charge Pump: CPH, CPL, CP
    3. 2.3 Buck Converter: FB_BK, SW_BK, GND_BK
    4. 2.4 AVDD
    5. 2.5 DVDD
    6. 2.6 PGND, AGND, DGND
    7. 2.7 Thermal Pad
  6. 3MCF831xC Buck Regulator Overview
    1. 3.1 Buck Regulator Mode of Operation
    2. 3.2 Buck Regulator Output Voltage
    3. 3.3 Buck Power Sequencing
    4. 3.4 Buck Inductor Selection
    5. 3.5 MCF831xC Operation Without Buck Regulator
  7. 4MCF831xC IO Pins Design Recommendations
    1. 4.1 SPEED Pin
    2. 4.2 BRAKE, DIR, DRVOFF pins
    3. 4.3 EXT_CLK, EXT_WD
    4. 4.4 ALARM
    5. 4.5 DACOUT1, DACOUT2
    6. 4.6 SDA, SCL
    7. 4.7 nFAULT and FG pin
  8. 5MCF831xC PCB Schematic and Layout Recommendations
    1. 5.1 Single Ground Plane
    2. 5.2 Single Ground with AVDD Shorted to FB_BK
    3. 5.3 Two Grounds
  9. 6Summary
  10. 7References

2.3 Buck Converter: FB_BK, SW_BK, GND_BK

MCF831xC has an integrated buck regulator that can provide up to 170mA of external load current at a user configurable voltage (3.3 or 4 or 5 or 5.7V). Depending on the external load current requirements, the buck regulator can be operated in inductor or resistor mode to optimize costs against load current capability.

To further optimize costs, the buck regulator can be disabled by setting BUCK_DIS bit in EEPROM to 1b and connecting FB_BK to AVDD. Refer to Section 3.5 for more details.