SLVSD29 October 2015 DRV8704
PRODUCTION DATA.
IDRIVE and TDRIVE are selected based on the size of external FETs used. These registers need to be configured so that the FET gates are charged completely during TDRIVE. If IDRIVE and TDRIVE are chosen to be too low for a given FET, then the FET may not turn on completely. It is suggested to adjust these values in-system with the required external FETs and motors in order to determine the best possible setting for any application.
Note that TDRIVE will not increase the PWM time or change the PWM chopping frequency.
In a system with capacitor charge Q and desired rise time RT, IDRIVE, and TDRIVE can be initially selected based on:
For best results, select the smallest IDRIVE and TDRIVE that meet the above conditions.
Example:
If the gate charge is 15 nC and the desired rise time is 400 ns, then select
IDRIVEP = 50 mA, IDRIVEN = 100 mA
TDRIVEP = TDRIVEN = 1050 ns