DRV10975_15 Datasheet, PDF (35/57 Pages) Texas Instruments – DRV10975 12-V, Three-Phase, Sensorless BLDC Motor Driver

www.ti.com
Motor phase
driving voltage
FGOLset = 00
FGOLset = 01
Open loop
Closed loop
DRV10975
SLVSCP2 – JANUARY 2015
Motor phase
driving voltage
Open loop
Closed loop
Open loop
Closed loop
FGOLset = 10
Start-up after power-on or wake
up from sleep/standby mode
Rest of the startups
Figure 36. FG Behavior During Open Loop
9.4.11 Diagnostics and Visibility
The DRV10975 offers extensive visibility into the motor system operation conditions stored in internal registers.
This information can be monitored through the I²C interface. Information can be monitored relating to the device
status, motor speed, supply voltage, speed command, motor phase voltage amplitude, fault status, and others.
The data is updated on the fly.
9.4.11.1 Motor Status Read Back
The motor status register provides information on over-temperature (OverTemp), sleep or standby state
(Slp_Stdby), over current (OverCurr), and locked rotor (MtrLck).
9.4.11.2 Motor Speed Read Back
The motor operation speed is automatically updated in register MotorSpeed1 and MotorSpeed2 while the motor
is spinning. MotorSpeed1 contains the 8 most significant bits and MotorSpeed2 contains the 8 least significant
bits. The value is determined by the period for calculated BEMF zero crossings on phase U. The electrical speed
of the motor is denoted as ‘Velocity (Hz)’ and is calculated as shown in Equation 7.
Velocity (Hz) = {MotorSpeed1:MotorSpeed2} / 10
(7)
As an example consider the following:
MotorSpeed1 = 0x01;
MotorSpeed2 = 0xFF;
Velocity = 512 (0x01FF) / 10 = 51 Hz
51 ^ecycles K ^{1 mechcycle} K 60 ^{sec ond}  1530 RPM
For a 4-pole motor, this translates to: ^{sec ond 2 ecycle}
minute
Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV10975
Submit Documentation Feedback
35