8.4.10.1 FG Output Frequency

The FG output frequency can be configured by FGcycle[1:0]. The default FG toggles once every electrical cycle (FGcycle = 00). Many applications configure the FG output so that it provides two pulses for every mechanical rotation of the motor. The configuration bits provided in DRV10983 can accomplish this for 4-pole, 6-pole, 8-pole, and 12-pole motors, as shown in Figure 36.

Figure 36 shows the DRV10983 has been configured to provide FG pulses once every electrical cycle (4 pole), twice every three electrical cycle (6 pole), once every two electrical cycles (8 pole), and once every three electrical cycles (12 pole).

Note that when it is set to 2 FG pulses every three electrical cycles, the FG output is not 50% duty cycle. Motor speed is able to be measured by monitoring the rising edge of the FG output.

Figure 36. FG Frequency Divider