18.104.22.168.1 External MOSFET Support
The DRV835x family of devices MOSFET support is based on the MOSFET gate charge, VCP charge-pump capacity, VGLS regulator capacity, and output PWM switching frequency. For a quick calculation of MOSFET driving capacity, use Equation 11 and Equation 12 for three phase BLDC motor applications.
Equation 11. Trapezoidal 120° Commutation: IVCP/VGLS > Qg × ƒPWM
Equation 12. Sinusoidal 180° Commutation:
> 3 × Qg
- ƒPWM is the maximum desired PWM switching frequency.
- Qg is the MOSFET total gate charge
- IVCP/VGLS is the charge pump or low-side regulator capacity, dependent on the VM pin voltage.
- The MOSFET multiplier based on the commutation control method, may vary based on implementation.