Datasheet

TMC2130 DATASHEET (Rev. 1.09 / 2017-MAY-15) 46
www.trinamic.com
6.6 Freewheeling and Passive Motor Braking
stealthChop provides different options for motor standstill. These options can be enabled by setting
the standstill current IHOLD to zero and choosing the desired option using the FREEWHEEL setting.
The desired option becomes enabled after a time period specified by TPOWERDOWN and
IHOLD_DELAY. The PWM_SCALE regulation becomes frozen once the motor target current is at zero
current in order to ensure a quick startup.
Parameter
Description
Setting
Comment
en_pwm_
mode
General enable for use of stealthChop (register
GCONF)
0
Do not use stealthChop
1
stealthChop enabled
TPWMTHRS
Specifies the upper velocity for operation in
stealthChop voltage PWM mode. Entry the TSTEP
reading (time between two microsteps) when
operating at the desired threshold velocity.
0 …
1048575
stealthChop also is
disabled if TSTEP falls
below TCOOLTHRS or
THIGH
pwm_
autoscale
Enable automatic current scaling using current
measurement or use forward controlled velocity
based mode.
0
Forward controlled mode
1
Automatic scaling with
current regulator
PWM_FREQ
PWM frequency selection. Use the lowest setting
giving good results. The frequency measured at
each of the chopper outputs is half of the
effective chopper frequency f
PWM
.
0
f
PWM
=2/1024 f
CLK
1
f
PWM
=2/683 f
CLK
2
f
PWM
=2/512 f
CLK
3
f
PWM
=2/410 f
CLK
PWM_GRAD
User defined PWM amplitude (gradient) for
velocity based scaling or regulation loop gradient
when pwm_autoscale=1.
1 … 15
With pwm_autoscale=1
0 … 255
With pwm_autoscale=0
PWM_AMPL
User defined PWM amplitude (offset) for velocity
based scaling or amplitude limit for re-entry into
stealthChop mode when pwm_autoscale=1.
0 … 255
pwm_
symmetric
Activate to force a symmetric PWM for each cycle.
Reduces the number of updates to the PWM cycle.
Special use only.
0
Normal operation
1
A symmetric PWM cycle
is enforced
FREEWHEEL
Stand still option when motor current setting is
zero (I_HOLD=0). Only available with stealthChop
enabled. The freewheeling option makes the
motor easy movable, while both coil short options
realize a passive brake. Mode 2 will brake more
intensely than mode 3, because low side drivers
(LS) have lower resistance than high side drivers.
0
Normal operation
1
Freewheeling
2
Coil shorted using LS
drivers
3
Coil shorted using HS
drivers
PWM_SCALE
Read back of the actual stealthChop voltage PWM
scaling as determined by the current regulation.
Can be used to detect motor load and stall when
autoscale=1.
0 … 255
(read
only)
The scaling value
becomes frozen when
operating in a different
chopper mode
TOFF
General enable for the motor driver, the actual
value does not influence stealthChop
0
Driver off
1 … 15
Driver enabled
TBL
Comparator blank time. This time needs to safely
cover the switching event and the duration of the
ringing on the sense resistor. Choose a setting of
1 or 2 for typical applications. For higher
capacitive loads, 3 may be required. Lower
settings allow stealthChop to regulate down to
lower coil current values.
0
16 t
CLK
1
24 t
CLK
2
36 t
CLK
3
54 t
CLK
IRUN
IHOLD
Run and hold current setting for stealth Chop
operation – only used with pwm_autoscale=1
See chapter on current
setting for details