DRV10975ZPWPR datasheet(36/65 Pages) TI1

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= 0

MIN

= BEMF + I

Rm = BEMF

U_MIN

MIN ´

BEMF

DRV10975

DRV10975, DRV10975Z

SLVSCP2E – JANUARY 2015 – REVISED MAY 2018

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Product Folder Links: DRV10975

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Figure 33. No Motor Error

8.4.7.5 Lock4: Open Loop Motor Stuck Lock

Lock4 is used to detect locked motor conditions while the motor start sequence is in open loop.

For a successful startup, motor speed should equal to open to closed loop handoff threshold when the motor is

transitioning into closed loop. However, if the motor is locked, the motor speed is not able to match the open loop

drive rate.

If the motor BEMF is not detected for one electrical cycle after the open loop drive rate exceeds the threshold,

then the open loop was unsuccessful as a result of a locked rotor condition.

8.4.7.6 Lock5: Closed Loop Motor Stuck Lock

If the motor suddenly becomes locked, motor speed and Ktc are not able to be refreshed because motor BEMF

zero cross may not appear after the lock. In this condition, lock can also be detected by the following scheme: if

the current commutation period is 2× longer than the previous period.

8.4.8 AVS Function

When a motor is driven, energy is transferred from the power supply into it. Some of this energy is stored in the

form of inductive energy or as mechanical energy. The DRV10975 includes circuits to prevent this energy from

being returned to the power supply which could result in pumping up the VCC voltage. This function is referred to

as the AVS and acts to protect the DRV10975 as well as other circuits that share the same VCC connection. Two

forms of AVS protection are used to prevent both the mechanical energy or the inductive energy from being

returned to the supply. Each of these modes can be independently disabled through the register configuration

bits AVSMEn and AVSIndEn.

8.4.8.1 Mechanical AVS Function

If the speed command suddenly drops such that the BEMF voltage generated by the motor is greater than the

voltage that is applied to the motor, then the mechanical energy of the motor is returned to the power supply and

the VCC voltage surges. The mechanical AVS function works to prevent this from happening. The DRV10975

buffers the speed command value and limits the resulting output voltage, UMIN, so that it is not less than the

BEMF voltage of the motor. The BEMF voltage in the mechanical AVS function is determined using the

programmed value for the Kt of the motor (Kt[6:0]) along with the speed. Figure 34 shows the criteria used by the

mechanical AVS function.

Figure 34. Mechanical AVS

The mechanical AVS function can operate in one of two modes, which can be configured by the register bit

AVSMMd:

AVSMMd = 0 – AVS mode is always active to prevent the applied voltage from being less than the BEMF

voltage.

DRV10975ZPWPR Datasheet(PDF) 36 Page - Texas Instruments

DRV10975ZPWPR Datasheet(HTML) 36 Page - Texas Instruments

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