DRV10975ZPWPR datasheet(34/65 Pages) TI1

34 / 65 page

DAC

Digital Core

–

Lock-Detection Current Limit

Speed Abnormal

Open-Loop Stuck

Closed-Loop Stuck

No-Motor Fault

LockEn (0, 1, 2, 3, 4, 5)

Hi-Z

and Restart

Logic

FaultCode [5:0]

Status[4]

Set

Reset

BEMF Abnormal

DRV10975, DRV10975Z

SLVSCP2E – JANUARY 2015 – REVISED MAY 2018

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Product Folder Links: DRV10975

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Figure 28. Lock Detect and Fault Diagnose

8.4.7.1 Lock0: Lock Detection Current Limit Triggered

The lock detection current limit function provides a configurable threshold for limiting the current to prevent

damage to the system. This is often tripped in the event of a sudden locked rotor condition. The DRV10975

continuously monitors the current in the low-side drivers as shown in Figure 29. If the current goes higher than

the threshold configured by the HWiLimitThr[2:0] bits, then the DRV10975 stops driving the motor by placing the

output phases into a high-impedance state. The MtrLck bit is set and a lock condition is reported. It retries after

tLOCK_OFF.

Set the lock detection current limit to a higher value than the acceleration current limit.

Figure 29. Lock Detection Current Limit

8.4.7.2 Lock1: Abnormal Speed

If motor is operating normally, the motor BEMF should always be less than output amplitude. The DRV10975

uses two methods of monitoring the BEMF in the system. The U phase current is monitored to maintain an

estimate of BEMF based on the setting for Rm[6:0]. In addition, the BEMF is estimated based on the operation

speed of the motor and the setting for Kt[6:0]. Figure 30 shows the method for using this information to detect a

lock condition. If motor BEMF is much higher than output amplitude for a certain period of time, tLCK_ETR, it means

the estimated speed is wrong, and the motor has gotten out of phase.

DRV10975ZPWPR Datasheet(PDF) 34 Page - Texas Instruments