DRV10975 Datasheet, PDF (22/57 Pages) Texas Instruments – 12-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10975
SLVSCP2 – JANUARY 2015
www.ti.com
9.4.3.5.2.2 IPD Release Mode
Two options are available for stopping the voltage applied to the motor when the current threshold is reached. If
IPDRlsMd = 0, the recirculate mode is selected. The low-side (S6) MOSFET remains on to allow the current to
recirculate between the MOSFET (S6) and body diode (S2) (see Figure 13). If IPDRlsMd = 1, the tri-state mode
is selected. Both the high-side (S1) and low-side (S6) MOSFETs are turned off and the current flies back across
the body diodes into the power supply (see Figure 14).
The tri-state mode has a faster settle-down time, but could result in a surge on VCC. Manage this with
appropriate selection of either a clamp circuit or by providing sufficient capacitance between VCC and GND. If
the voltage surge cannot be contained and if it is unacceptable for the application, then select the recirculate
mode. When selecting the recirculate mode, select the IPDClk[1:0] bits to give the current in the motor’s windings
enough time to decay to 0.
S1
S3
S5
U1
M
S2
S4
S6
S1
S3
S5
U1
M
S2
S4
S6
Driving
Brake (Recirculate)
Figure 13. IPD Release Mode 0
S1
S3
S5
U1
M
S2
S4
S6
S1
S3
S5
U1
M
S2
S4
S6
Driving
Hi-Z (Tri-State)
Figure 14. IPD Release Mode 1
9.4.3.5.2.3 IPD Advance Angle
After the initial position is detected, the DRV10975 begins driving the motor at an angle specified by
IPDAdvcAgl[1:0].
Advancing the drive angle anywhere from 0° to 180° results in positive torque. Advancing the drive angle by 90°
results in maximum initial torque. Applying maximum initial torque could result in uneven acceleration to the rotor.
Select the IPDAdvcAgl[1:0] to allow for smooth acceleration in the application (see Figure 15).
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