SLVAFZ3 December   2024 DRV8161 , DRV8162 , DRV8350 , DRV8350F , DRV8353 , DRV8353F

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2System Power Requirements
  6. 3Motor Current and MOSFET Selection
    1. 3.1 How Does a BLDC Motor Driver System Work?
    2. 3.2 Motor Current and QG Value Relation
    3. 3.3 Role of a Motor Driver
    4. 3.4 Can my MOSFET be Driven or Commutated?
      1. 3.4.1 Example 1 – Medium Power (4.8kW – 48V × 100A)
      2. 3.4.2 Example 2 – High Power (19.2kW – 48V × 400A)
  7. 4Motor Driver Specifications to Consider
    1. 4.1 DRV8353 - Internally Generated Gate Drive Supply
    2. 4.2 DRV8161/DRV8162 – Externally Generated Gate Drive Supply
  8. 5Advantages of TI’s BLDC Drivers With Smart Gate Drive
  9. 6Maximum Source and Sink Current and QGD
  10. 7Older Designs
  11. 8Summary
  12. 9References

6 Maximum Source and Sink Current and QGD

For increasing switching efficiency in robotic applications, the rise time up to 48V can be as little as 100ns. Using the 1A peak source setting, the peak QGD MOSFET that can be switched is calculated as shown below:

Equation 5. 100ns = QGDmax/1A
Equation 6. QGDmax = 100nC

In earlier Example 2 with 19.2kW application, a MOSFET with 40nC QGD was sufficient. Therefore, the driver can be used to scale for higher power applications if needed.

Note: In reality, achieving extremely fast slew rates can result in switch node ringing issues or other power stage related transient issues, so trade-offs needs to be considered for each specific system.