L6470HTR STMicroelectronics, L6470HTR Datasheet - Page 30

• Manufacturer Part Number: L6470HTR
• Description: IC STEPPER/DC MOTOR DVR 28HTSSOP
• Manufacturer: STMicroelectronics

Specifications of L6470HTR

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-10812-2

Phase current control
7
7.1
30/64
Phase current control
The L6470 controls the phase current applying a sinusoidal voltage to motor windings.
Phase current amplitude is not directly controlled but depends on phase voltage amplitude,
load torque, motor electrical characteristics and rotation speed. Sinewave amplitude is
proportional to the motor supply voltage multiplied by a coefficient (K
0 to 100% and the sinewave amplitude can be obtained through the following formula:
Equation 1
Different K
phases and when motor is stopped (HOLD phase) through KVAL_ACC, KVAL_DEC,
KVAL_RUN and KVAL_HOLD registers (see paragraph 9.1.10). KVAL value is calculated
according following formula:
Equation 2
Where K
(KVAL_ACC, KVAL_DEC, KVAL_RUN or KVAL_HOLD), BEMF_COMP is the BEMF
compensation curve value, VSCOMP and K_THERM are the motor supply voltage and
winding resistance compensation factors and microstep is the current microstep value
(fraction of target peak current).
L6470 offers various methods to guarantee a stable current value, allowing the
compensation of:
●
●
●
●
PWM sinewave generators
The two voltage sinewaves applied to stepper motor phases are generated by two PWM
modulators.
The PWM frequency (f
obtained through the following formula:
Equation 3
'N' is the integer division factor and 'm' is the multiplication factor. 'N' and 'm' values can be
programmed by F_PWM_INT and F_PWM_DEC parameters in CONFIG register (see
Table 27
Available PWM frequencies are listed in paragraph
low speed optimization (see paragraph 7.3)
back electromotive force value (see paragraph 7.4);
motor supply voltage variation (see paragraph 7.5);
windings resistance variation (see paragraph 7.6).
VAL_X
and
K
VAL
VAL
Table
values can be programmed for acceleration, deceleration and constant speed
is the starting K
=
(
(
K
28, paragraph 9.1.21).
VAL_X
PWM
+
) is proportional to the oscillator frequency (f
BEMF
Doc ID 16737 Rev 2
VAL
value programmed for present motion phase
_
COMP
f
V
PWM
OUT
=
)
=
×
512
V
VSCOMP
f
OSC
S
⋅
⋅
K
N
VAL
9.1.21
⋅
m
×
K
from
_
THERM
Table 29
VAL
)
×
microstep
OSC
). K
to
Table
VAL
) and can be
ranges from
32.
L6470