DRV10975_15 Datasheet, PDF (14/57 Pages) Texas Instruments – DRV10975 12-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10975
SLVSCP2 – JANUARY 2015
www.ti.com
Feature Description (continued)
Speed
Command
Mode
I²C
Table 1. Conditions to Enter or Exit Sleep or Standby Condition (continued)
Enter Sleep/Standby Condition
SpdCtrl[8:0] is programmed as 0 for
T_{EN_SL_SB}
Exit from Standby Condition
Exit from Sleep Condition
SpdCtrl[8:0] is programmed as non-zero SPEED pin high ( V > V_{DIG_IH}) for
for T_{EX_SL_SB}
T_{EX_SL_SB}
Note that using the analog speed command, a higher voltage is required to exit from the sleep condition than the
standby condition. The I²C speed command cannot take the device out of the sleep condition because I²C
communication is disabled during the sleep condition.
9.3.5 Non-Volatile Memory
DRV10975 has 96-bits of EEPROM data, which are used to program the motor parameters as described in the
I²C Serial Interface.
The procedure for programming the EEPROM is as follows. TI recommends to perform the EEPROM
programming without the motor spinning, power cycle after the EEPROM write, and read back the EEPROM to
verify the programming is successful.
1. Set SIdata = 1.
2. Write the desired motor parameters into the corresponding registers (address 0x20:0x2B) (see I²C Serial
Interface).
3. Write ‘10110110’ (0xB6) to enProgKey in the DevCtrl register.
4. Ensure that VCC is at or above 22 V.
5. Write eeWrite = 1 in EECtrl register to start the EEPROM programming.
The programming time is about 24 ms, and eeWrite bit is reset to 0 when programming is done.
9.4 Device Functional Modes
This section includes the logic required to be able to reliably start and drive the motor. It describes the processes
used in the logic core and provides the information needed to effectively configure the parameters to work over a
wide range of applications.
9.4.1 Motor Parameters
Refer to the DRV10975/83 Tuning Guide for the motor parameter measurement.
The motor resistance and motor velocity constant are two important parameters used to characterize a BLDC
motor. The DRV10975 requires these parameters to be configured in the register. The motor resistance is
programmed by writing the values for Rm[6:0] in the MotorParam1 register. The motor velocity constant is
programmed by writing the values for Kt[6:0] in the MotorParam2 register.
9.4.1.1 Motor Resistance
The motor resistance (R_{PH_CT}) must be converted to a 7-bit digital register value Rm[6:0] to program the motor
resistance value. The digital register value can be determined as follows:
1. Convert the motor resistance (R_{PH_CT}) to a digital value where the LSB is weighted to represent 7.35 mΩ:
Rmdig = R_{PH_CT} / 0.00735.
2. Encode the digital value such that Rmdig = Rm[3:0] << Rm[6:4].
The maximum resistor value, R_{PH_CT}, that can be programmed for the DRV10975 is 14.1 Ω, which represents
Rmdig = 1920 and an encoded Rm[6:0] value of 0x7Fh. The minimum resistor the DRV10975 supports is 0.0294
Ω, R_{PH_CT}, which represents Rmdig = 4.
For convenience, the encoded value for Rm[6:0] can also be obtained from Table 2.
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