Datasheet
TMC2130 DATASHEET (Rev. 1.09 / 2017-MAY-15) 56
www.trinamic.com
When I_scale_analog is enabled for analog scaling of V
FS
, the resulting voltage V
FS
‘ is calculated by:
with V
AIN
the voltage on pin AIN_IREF in the range 0V to V
5VOUT
/2
The sense resistor needs to be able to conduct the peak motor coil current in motor standstill
conditions, unless standby power is reduced. Under normal conditions, the sense resistor conducts
less than the coil RMS current, because no current flows through the sense resistor during the slow
decay phases.
CALCULATION OF PEAK SENSE RESISTOR POWER DISSIPATION
Hint
For best precision of current setting, it is advised to measure and fine tune the current in the
application.
Attention
Be sure to use a symmetrical sense resistor layout and short and straight sense resistor traces of
identical length. Well matching sense resistors ensure best performance.
A compact layout with massive ground plane is best to avoid parasitic resistance effects.
Parameter
Description
Setting
Comment
IRUN
Current scale when motor is running. Scales coil
current values as taken from the internal sine
wave table. For high precision motor operation,
work with a current scaling factor in the range 16
to 31, because scaling down the current values
reduces the effective microstep resolution by
making microsteps coarser. This setting also
controls the maximum current value set by
coolStep.
0 … 31
scaling factor
1/32, 2/32, … 32/32
IHOLD
Identical to IRUN, but for motor in stand still.
IHOLD
DELAY
Allows smooth current reduction from run current
to hold current. IHOLDDELAY controls the number
of clock cycles for motor power down after
TPOWERDOWN in increments of 2^18 clocks:
0=instant power down, 1..15: Current reduction
delay per current step in multiple of 2^18 clocks.
Example: When using IRUN=31 and IHOLD=16, 15
current steps are required for hold current
reduction. A IHOLDDELAY setting of 4 thus results
in a power down time of 4*15*2^18 clock cycles,
i.e. roughly one second at 16MHz.
0
instant IHOLD
1 …15
1*2
18
… 15*2
18
clocks per current
decrement
vsense
Allows control of the sense resistor voltage range
for full scale current.
0
V
FS
= 0.32 V
1
V
FS
= 0.18 V