SLVA959B November   2018  – October 2021 DRV10866 , DRV10963 , DRV10964 , DRV10970 , DRV10974 , DRV10975 , DRV10983 , DRV10983-Q1 , DRV10987 , DRV11873 , DRV3205-Q1 , DRV3220-Q1 , DRV3245E-Q1 , DRV3245Q-Q1 , DRV8301 , DRV8302 , DRV8303 , DRV8304 , DRV8305 , DRV8305-Q1 , DRV8306 , DRV8307 , DRV8308 , DRV8312 , DRV8313 , DRV8320 , DRV8320R , DRV8323 , DRV8323R , DRV8332 , DRV8343-Q1 , DRV8350 , DRV8350R , DRV8353 , DRV8353R , DRV8412 , DRV8701 , DRV8702-Q1 , DRV8702D-Q1 , DRV8703-Q1 , DRV8703D-Q1 , DRV8704 , DRV8711 , DRV8800 , DRV8801 , DRV8801-Q1 , DRV8801A-Q1 , DRV8802 , DRV8802-Q1 , DRV8803 , DRV8804 , DRV8805 , DRV8806 , DRV8811 , DRV8812 , DRV8813 , DRV8814 , DRV8816 , DRV8818 , DRV8821 , DRV8823 , DRV8823-Q1 , DRV8824 , DRV8824-Q1 , DRV8825 , DRV8828 , DRV8829 , DRV8830 , DRV8832 , DRV8832-Q1 , DRV8833 , DRV8833C , DRV8834 , DRV8835 , DRV8836 , DRV8837 , DRV8837C , DRV8838 , DRV8839 , DRV8840 , DRV8841 , DRV8842 , DRV8843 , DRV8844 , DRV8846 , DRV8847 , DRV8848 , DRV8850 , DRV8860 , DRV8870 , DRV8871 , DRV8871-Q1 , DRV8872 , DRV8872-Q1 , DRV8873-Q1 , DRV8880 , DRV8881 , DRV8884 , DRV8885 , DRV8886 , DRV8886AT , DRV8889-Q1

 

  1.   Trademarks
  2. 1Grounding Optimization
    1. 1.1 Frequently Used Terms/Connections
    2. 1.2 Using a Ground Plane
      1. 1.2.1 Two-Layer Board Techniques
    3. 1.3 Common Problems
      1. 1.3.1 Capacitive and Inductive Coupling
      2. 1.3.2 Common and Differential Noise
    4. 1.4 EMC Considerations
  3. 2Thermal Overview
    1. 2.1 PCB Conduction and Convection
    2. 2.2 Continuous Top-Layer Thermal Pad
    3. 2.3 Copper Thickness
    4. 2.4 Thermal Via Connections
    5. 2.5 Thermal Via Width
    6. 2.6 Summary of Thermal Design
  4. 3Vias
    1. 3.1 Via Current Capacity
    2. 3.2 Via Layout Recommendations
      1. 3.2.1 Multi-Via Layout
      2. 3.2.2 Via Placement
  5. 4General Routing Techniques
  6. 5Bulk and Bypass Capacitor Placement
    1. 5.1 Bulk Capacitor Placement
    2. 5.2 Charge Pump Capacitor
    3. 5.3 Bypass/Decoupling Capacitor Placement
      1. 5.3.1 Near Power Supply
      2. 5.3.2 Near Power Stage
      3. 5.3.3 Near Switch Current Source
      4. 5.3.4 Near Current Sense Amplifiers
      5. 5.3.5 Near Voltage Regulators
  7. 6MOSFET Placement and Power Stage Routing
    1. 6.1 Common Power MOSFET Packages
      1. 6.1.1 DPAK
      2. 6.1.2 D2PAK
      3. 6.1.3 TO-220
      4. 6.1.4 8-Pin SON
    2. 6.2 MOSFET Layout Configurations
    3. 6.3 Power Stage Layout Design
      1. 6.3.1 Switch Node
      2. 6.3.2 High-Current Loop Paths
      3. 6.3.3 VDRAIN Sense Pin
  8. 7Current Sense Amplifier Routing
    1. 7.1 Single High-Side Current Shunt
    2. 7.2 Single Low-Side Current Shunt
    3. 7.3 Two-Phase and Three-Phase Current Shunt Amplifiers
    4. 7.4 Component Selection
    5. 7.5 Placement
    6. 7.6 Routing
    7. 7.7 Useful Tools (Net Ties and Differential Pairs)
    8. 7.8 Input and Output Filters
    9. 7.9 Do's and Don'ts
  9. 8References
  10. 9Revision History

2.2 Continuous Top-Layer Thermal Pad

Connecting the thermal pad to a solid copper plane is an important requirement to create an exit path for heat generated in the driver die. For the heat to flow away from the device, copper planes must be continuous from the thermal pad to other areas on the board. A best practice is to include a wide exit path from the copper fill underneath the driver into a wide, high surface area plane. If these planes are interrupted, the exit path for heat is constricted which increases the thermal resistance. An increase in the thermal resistance creates a larger temperature differential between the thermal pad and wider surface area on the same plane. Figure 2-2 shows an example of temperature rise from constricted versus continuous ground pours underneath the driver.

GUID-EC0DA8BC-DB08-4A09-B8FC-13CD3EB478FA-low.gifFigure 2-2 Broken Ground vs Continuous Ground Pour Heat Map

Keeping a continuous copper thermal pad underneath the driver is important for efficient device cooling. Incorporating wide paths to high surface area planes keeps the thermal resistance at a minimum between the driver thermal pad and ambient air temperature.