TMC5161 DATASHEET (Rev. 1.01 / 2018-NOV-20)
71
CALCULATION OF PEAK SENSE RESISTOR POWER DISSIPATION
2
푃ꢟꢓ푀퐴푋 = 퐼ꢋ푂ꢌ퐿 ∗ 푅ꢓꢔ푁ꢓꢔ
Hint
For best precision of current setting, it is advised to measure and fine tune the current in the
application. Choose the sense resistors to the next value covering the desired motor current. Set IRUN
to 31 corresponding 100% of the desired motor current and fine-tune motor current using
GLOBALSCALER.
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 0 … 31
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.
scaling factor
1/32, 2/32, … 32/32
IHOLD
IHOLD
DELAY
Identical to IRUN, but for motor in stand still.
Allows smooth current reduction from run current 0
to hold current. IHOLDDELAY controls the number
of clock cycles for motor power down after
TZEROWAIT in increments of 2^18 clocks: 0=instant
power down, 1..15: Current reduction delay per
current step in multiple of 2^18 clocks.
instant IHOLD
1 … 15 1*218 … 15*218
clocks per current
decrement
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.
GLOBAL
SCALER
Allows fine control of the motor current range
setting. Use for initial tuning, only.
0 … 255 scales in 1/256 steps
0=full scale
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TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
