SLOA198A September   2014  – December 2021 DRV2665 , DRV2667 , DRV2700 , DRV8662

 

  1.   Trademarks
  2. 1 Boost Converter Basics
  3. 2 DRV8662, DRV2700, DRV2665, and DRV2667 Boost Converter
    1. 2.1 DRV8662, DRV2700, DRV2665, and DRV2667 Boost Converter Efficiency
      1. 2.1.1 Boost Efficiency vs Boost Current
    2. 2.2 DRV8662, DRV2700, DRV2665, and DRV2667 Boost Converter Load Regulation
      1. 2.2.1 Boost Regulation vs Current
  4. 3 Configuring the Boost Converter
  5. 4 Boost Converter Output Voltage
  6. 5 Calculating the Load Current
  7. 6 Selecting an Inductor
    1. 6.1 Inductance Rating
    2. 6.2 Saturation Current Rating
    3. 6.3 Thermal Current Rating
    4. 6.4 Choosing REXT
    5. 6.5 What to Avoid: Using Incorrect Inductor Current Ratings
  8. 7 Calculate the Maximum Boost Current
  9. 8 Output Capacitor Selection
  10. 9 Input Capacitor Selection
  11. 10PCB Layout
    1. 10.1 What to Avoid: Incorrect Inductor Placement
  12. 11Examples
    1. 11.1 Example: Based on the DRV8662EVM
      1. 11.1.1 Configure the Boost Voltage
      2. 11.1.2 Configure the Inductor Current
      3. 11.1.3 Boost Performance Results
    2. 11.2 Example: Based on the DRV2667EVM-CT with 25-nF Piezo Module
      1. 11.2.1 Configure the Boost Voltage
      2. 11.2.2 Configure the Inductor Current
      3. 11.2.3 Boost Performance Results
  13. 12Revision History

10 PCB Layout

Use the following guidelines for PCB layout.

GUID-E786769C-47B3-4BDB-A42B-3CB09C5F1129-low.gif
  1. Place the feedback resistors, R1 and R2, close to the FB pin. If the resistors are placed far from the FB pin, then noise can enter the FB trace and causes instability or unwanted ripple.
  2. Protect the feedback trace (Red trace). Isolate the feedback trace on a different layer and shield from the SW node using a ground plane.
  3. Minimize the size of SW node trace. The trace between the SW pins and the inductor terminal should be as physically small as possible. A large switch node can add parasitic capacitance and slow the switching frequency of the boost converter, preventing it from delivering the required current. A small SW node also helps prevent radiated emissions.
  4. Place the bulk input capacitor near the inductor. The bulk input capacitor provides the current during quick transient current spikes. Closer means less resistance between the bulk capacitor and inductor.
  5. Place the output capacitor near the VBST pin.