The first data set shows how both output current and PWM frequency affect the temperature of the device package. These measurements were made using the DRV8317 and the following parameters: the supply voltage was set to 17.4V, the slew rate was set to a maximum value of 200V/μs, the motor was characterized while unloaded, and the measurements were made within 10-60 seconds of the device achieving the output current. Note that the internal linear regulator of the DRV8317 contributes to the power loss of the device, and this output was consistent between tests.

Table 3-1 shows the effects of both increasing PWM frequency and current in action. First, while holding the PWM frequency constant and comparing the package temperature with respect to the two different output current RMS values, the data show that a higher current output can significantly increase the temperature of the device. This is expected, as the conduction loss dominates at high current output, and is determined by the R_ds(on) of the device. Second, while holding the output current RMS constant and comparing the package temperature with respect to increasing PWM frequency, the data show that high PWM frequency can also significantly increase the temperature of the device. This is expected from the switching and diode losses as discussed in the previous section.

Note that these data also show the device reaching towards the absolute maximum temperature threshold. While this threshold is typically 160 degrees Celsius according to the data sheet, device variation means that the threshold can be as low as 145 degrees Celsius or as high as 175 degrees Celsius. This can cause reliability issues across many devices when operating at these high current outputs. Thus, in practice, PWM frequency limits the amount of current which can be produced by the driver without causing permanent damage.