VDSLVL is an analog voltage used to directly set the VDS overcurrent threshold for overcurrent protection. It can be sourced directly from an analog voltage source (such as a digital-to-analog converter) or divided down from a voltage rail (such as a resistor divider from AVDD) as shown in Figure 9-7.

Equation 9 and Equation 10 can be used to set the required VDSLVL voltage using a resistor divider from a voltage source to establish an overcurrent limit given the R_DS,on of the MOSFETs used:

where:

• V_VDSLVL = VDSLVL voltage

• I_OCP = VDS overcurrent limit

• R_DS,on = MOSFET on-resistance

• V_IN = voltage source for VDSLVL voltage divider

• R1/R2 = resistor ratio for setting VDSLVL

For example, if a resistor divider from AVDD is used to set an overcurrent trip threshold of 30-A and the MOSFET R_DS(ON) = 10mΩ, then VDSLVL = 0.3V.

In some applications, there will be a difference between battery voltage (VBAT) to directly drive motor power and PVDD voltage to power the DRV8328. Because high-side VDS monitoring is referenced from PVDD-SHx, VDSLVL needs to be selected appropriately to accommodate for the difference in VBAT and PVDD.

Equation 11 helps select an appropriate VDSLVL if there is a difference between PVDD and VDSLVL:

For instance, if VBAT = 24.0 V, PVDD = 23.3 V, Rdson = 10-mΩ, and I_OC = 30-A, then VDSLVL should equal 1.0V to detect a 30-A overcurrent event across the high-side FET and a 100-A overcurrent event across the low-side FET.