Speed(Hz)

Open loop to

close loop

transition

threshold

Close Loop

Open Loop

Accelerate

Time (s)

0 Align

Calibration

Align

Accelerate

Coasting

Close Loop

Kt

Measurement

300 ms

Resistance

Measurement

Wait T

OFF_LOCK

Power On

Open Loop

Closed Loop

Lock Detected

DRV10963

SLAS955A – MARCH 2013 – REVISED JULY 2015

www.ti.com

To align the rotor to the commutation logic the DRV10963 applies an x% duty cycle on phases V and W while

holding phase U at GND. This condition is maintained for TAlign seconds. The x% value is determined by the

VCC voltage (as shown in Table 2) to maintain sufficient driving torque over a wide range of supply voltages.

Figure 7. DRV10963 Initialization and Motor Start-up Sequence

Table 2. Align and Open Loop Duty Cycle

DUTY CYCLE DURING ALIGN

VCC VOLTAGE

AND OPEN LOOP (X)%

5.25 to approximately 6 V

43%

4.5 to approximately 5.25 V

50%

3.75 to approximately 4.5 V

60%

3 to approximately 3.75 V

75%

<3

100%

When the align phase completes, the motor is accelerated by applying sinusoidal phase voltages with peak

magnitudes as illustrated in Table 2 and stepping through the commutation sequence at an increasing rate

switches to closed loop mode where the commutation drive sequence is determined by the internal control

algorithm and the applied voltage is determined by the PWM commanded duty cycle input. The open loop to

through OTP settings (HO_TH[3:0], TARA_TH[3:0]).

Figure 8. DRV10963 Start-up Profile

handoff threshold that is as low as possible and allows the motor to smoothly and reliably transition between the

open loop acceleration and the closed loop acceleration. Normally higher speed motors (maximum speed)

require a higher handoff threshold because higher speed motors have lower Kt and as a result lower BEMF.

Table 3 shows the configurable settings for the handoff threshold. Maximum speed in electrical Hz are shown as

a guide to assist in identifying the appropriate handoff speed for a particular application.

10

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