Datasheet
Table Of Contents
- Table 1. Device summary
- 1 Block diagram
- 2 Electrical data
- 3 Electrical characteristics
- 4 Pin connection
- 5 Typical applications
- 6 Functional description
- 6.1 Device power-up
- 6.2 Logic I/O
- 6.3 Charge pump
- 6.4 Microstepping
- 6.5 Absolute position counter
- 6.6 Programmable speed profiles
- 6.7 Motor control commands
- 6.8 Internal oscillator and oscillator driver
- 6.9 Overcurrent detection
- 6.10 Undervoltage lockout (UVLO)
- 6.11 Thermal warning and thermal shutdown
- 6.12 Reset and standby
- 6.13 External switch (SW pin)
- 6.14 Programmable DMOS slew rate, deadtime and blanking time
- 6.15 Integrated analog-to-digital converter
- 6.16 Internal voltage regulator
- 6.17 BUSY\SYNC pin
- 6.18 FLAG pin
- 7 Phase current control
- 8 Serial interface
- 9 Programming manual
- 9.1 Registers and flags description
- Table 9. Register map
- 9.1.1 ABS_POS
- 9.1.2 EL_POS
- 9.1.3 MARK
- 9.1.4 SPEED
- 9.1.5 ACC
- 9.1.6 DEC
- 9.1.7 MAX_SPEED
- 9.1.8 MIN_SPEED
- 9.1.9 FS_SPD
- 9.1.10 KVAL_HOLD, KVAL_RUN, KVAL_ACC and KVAL_DEC
- 9.1.11 INT_SPEED
- 9.1.12 ST_SLP
- 9.1.13 FN_SLP_ACC
- 9.1.14 FN_SLP_DEC
- 9.1.15 K_THERM
- 9.1.16 ADC_OUT
- 9.1.17 OCD_TH
- 9.1.18 STALL_TH
- 9.1.19 STEP_MODE
- 9.1.20 ALARM_EN
- 9.1.21 CONFIG
- Table 22. CONFIG register
- Table 23. Oscillator management
- Table 24. External switch hard stop interrupt mode
- Table 25. Overcurrent event
- Table 26. Programmable power bridge output slew rate values
- Table 27. Motor supply voltage compensation enable
- Table 28. PWM frequency: integer division factor
- Table 29. PWM frequency: multiplication factor
- Table 30. Available PWM frequencies [kHz]: 8-MHz oscillator frequency
- Table 31. Available PWM frequencies [kHz]: 16-MHz oscillator frequency
- Table 32. Available PWM frequencies [kHz]: 24-MHz oscillator frequency
- Table 33. Available PWM frequencies [kHz]: 32-MHz oscillator frequency
- 9.1.22 STATUS
- 9.2 Application commands
- Table 37. Application commands
- 9.2.1 Command management
- 9.2.2 Nop
- 9.2.3 SetParam (PARAM, VALUE)
- 9.2.4 GetParam (PARAM)
- 9.2.5 Run (DIR, SPD)
- 9.2.6 StepClock (DIR)
- 9.2.7 Move (DIR, N_STEP)
- 9.2.8 GoTo (ABS_POS)
- 9.2.9 GoTo_DIR (DIR, ABS_POS)
- 9.2.10 GoUntil (ACT, DIR, SPD)
- 9.2.11 ReleaseSW (ACT, DIR)
- 9.2.12 GoHome
- 9.2.13 GoMark
- 9.2.14 ResetPos
- 9.2.15 ResetDevice
- 9.2.16 SoftStop
- 9.2.17 HardStop
- 9.2.18 SoftHiZ
- 9.2.19 HardHiZ
- 9.2.20 GetStatus
- 9.1 Registers and flags description
- 10 Package mechanical data
- 11 Revision history
Phase current control L6470
36/70 Doc ID16737 Rev 5
7.4 BEMF compensation
Using the speed information, a compensation curve is added to the amplitude of the voltage
waveform applied to the motor winding in order to compensate the BEMF variations during
acceleration and deceleration (see Figure 16).
The compensation curve is approximated by a stacked line with a starting slope (ST_SLP)
when speed is lower than a programmable threshold speed (INT_SPEED) and a fine slope
(FN_SLP_ACC and FN_SLP_DEC) when speed is greater than the threshold speed (see
Section 9.1.11, Section 9.1.12, Section 9.1.13 and Section 9.1.14).
To obtain different current values during acceleration and deceleration phases, two different
final slope values, and consequently two different compensation curves, can be
programmed.
The acceleration compensation curve is applied when the motor runs. No BEMF
compensation is applied when the motor is stopped.
7.5 Motor supply voltage compensation
The sinewave amplitude generated by the PWM modulators is directly proportional to the
motor supply voltage (V
S
). When the motor supply voltage is different from its nominal value,
the motor phases are driven with an incorrect voltage. The L6470 can compensate motor
supply voltage variations in order to avoid this effect.
The motor supply voltage should be connected to the integrated ADC input through a
resistor divider in order to obtain V
REG
/2 voltage at the ADCIN pin when V
S
is at its nominal
value (see Figure 17).
The ADC input is sampled at f
S
frequency, which is equal to PWM frequency.
Figure 16. BEMF compensation curve
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