SLVSD29 October 2015 DRV8704
PRODUCTION DATA.
The DRV8704 FET support is based on the charge pump capacity and output PWM frequency. For a quick calculation of FET driving capacity, use the following equations when drive and brake (slow decay) are the primary modes of operation:
where
The factor of two arises because there are two H-bridges present.
The current chopping frequency is at most:
Example:
If a system uses a maximum PWM frequency of 40 kHz, then the DRV8704 will support Qg < 250 nC FETs.
If the application will require a forced fast decay (or alternating between drive and reverse drive), the maximum FET driving capacity is given by: