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Part Number: DRV8711EVM
Our customer has a question about DRV8711EVM. I'm posting the question for the customer:
++++++++++++++++++++++++++++++++++++++++++++++We have found the following phenomenon on the DRV8711EVM.
After driving a motor, the motor would vibrate a little while holding.The wave form of the motor current is observed the current vibrated with unspecified cycle.It seems the ON time becomes short by adding a switch-noise on the SENSE signal .(Refer to:Fig1,Fig2)
The phenomenon doesn't always occur, but slight vibration occurs by a high rate.
Question; Would you let us know the way which stops vibrating ?
Mode: Full Step Blank time :75 ,1.5usISGAIN:10 Decay time : 5 ,2.5usTORQUE:114 ,(2.6A) Time OFF : 10 ,5usTDRIVEN:11 ,2us DECMODE : 011 ,Mixed decay all timeTDRIVEP:11 ,2us IDRIVEN:00 ,100mA IDRIVEN:00 ,50mA
MOTOR;Hybrid stepping motor - High-torque type,DC RESISTANCE: 0.6Ω±0.09INDUCTANCE at 1KHz 1Vrms: 2.6mHMAXIMUM CURRENT: 3A
The followings are the wave forms;
The followings are resister contents on DRV8711(another settings when abnormal):
// CTRL Register CTRL_REG.Address = 0x00; CTRL_REG.DTIME = 0x03; //850ns CTRL_REG.ISGAIN = 0x01; //Gain of 10 CTRL_REG.EXSTALL = 0x00; //Internal Stall Detect CTRL_REG.MODE = 0x00; //Full Step CTRL_REG.RSTEP = 0x00; //No Action CTRL_REG.RDIR = 0x00; //Direction set by DIR Pin CTRL_REG.ENBL = 0x01; //enable motor //1000 11 01 0 0000 0 0 1
/// TORQUE Register TORQUE_REG.Address = 0x01; TORQUE_REG.SIMPLTH = 0x01; //100uS Back EMF Sample Threshold TORQUE_REG.TORQUE = 0x71; //with ISGAIN set to 10 this gives about 1.2 AMP Current Chopper //1000 0 001 01110001 // OFF Register OFF_REG.Address = 0x02; OFF_REG.PWMMODE = 0x00; //Internal Indexer OFF_REG.TOFF = 0x0A; //5uS Fixed off time, It's same even at 10uS //1000 000 0 00001010
// BLANK Register BLANK_REG.Address = 0x03; BLANK_REG.ABT = 0x00; //disable adaptive blanking time BLANK_REG.TBLANK = 0x4B; //1.5uS current trip blanking time //1000 000 0 01001011
// DECAY Register. DECAY_REG.Address = 0x04; DECAY_REG.DECMOD = 0x03; //mixed decay at all times DECAY_REG.TDECAY = 0x05; //2.5uS mixed decay transition time, //1000 0011 00000101
// STALL Register STALL_REG.Address = 0x05; STALL_REG.VDIV = 0x02; //Back EMF is divided by 8 STALL_REG.SDCNT = 0x00; //stalln asserted on first step STALL_REG.SDTHR = 0x3C; //modifed value? //1000 10 00 00111100
// DRIVE Register DRIVE_REG.Address = 0x06; DRIVE_REG.IDRIVEP = 0x00; //High Side 50mA peak (source) DRIVE_REG.IDRIVEN = 0x00; //Low Side 100mA peak (sink) DRIVE_REG.TDRIVEP = 0x03; //High Side gate drive 2uS DRIVE_REG.TDRIVEN = 0x03; //Low Side Gate Drive 2uS DRIVE_REG.OCPDEG = 0x00; //OCP Deglitch Time 1uS DRIVE_REG.OCPTH = 0x00; //OCP Threshold 250mV //1000 00 00 11 11 00 00
Thank you in advance.
Rick DuncanMotor Applications Team
In reply to Rick Duncan:
In reply to takishin:
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