Datasheet

TMC5130A DATASHEET (Rev. 1.11 / 2015-OCT-08) 20
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3.8 Driver Protection and EME Circuitry
Some applications have to cope with ESD events caused by motor operation or external influence.
Despite ESD circuitry within the driver chips, ESD events occurring during operation can cause a reset
or even a destruction of the motor driver, depending on their energy. Especially plastic housings and
belt drive systems tend to cause ESD events. It is best practice to avoid ESD events by attaching all
conductive parts, especially the motors themselves to PCB ground, or to apply electrically conductive
plastic parts. In addition, the driver can be protected up to a certain degree against ESD events or live
plugging / pulling the motor, which also causes high voltages and high currents into the motor
connector terminals. A simple scheme uses capacitors at the driver outputs to reduce the dV/dt caused
by ESD events. Larger capacitors will bring more benefit concerning ESD suppression, but cause
additional current flow in each chopper cycle, and thus increase driver power dissipation, especially at
high supply voltages. The values shown are example values – they might be varied between 100pF
and 1nF. The capacitors also dampen high frequency noise injected from digital parts of the circuit
and thus reduce electromagnetic emission. A more elaborate scheme uses LC filters to de-couple the
driver outputs from the motor connector. Varistors eliminate coil overvoltage caused by live plugging.
As LC filters tend to oscillate, additional snubber elements have been added. The drawback of this
scheme is that it increases power dissipation significantly, especially at high supply voltages. A
dampening resistor in parallel to the ferrite inductivity would be an option to the snubbers.
Full Bridge A
Full Bridge B
stepper
motor
N
S
OA1
OA2
OB1
OB2
Driver
470pF
100V
470pF
100V
470pF
100V
470pF
100V
Full Bridge A
Full Bridge B
stepper
motor
N
S
OA1
OA2
OB1
OB2
Driver
4n7
50V
470pF
100V
470pF
100V
50Ohm @
100MHz
50Ohm @
100MHz
50Ohm @
100MHz
50Ohm @
100MHz
V1
V2
Fit Varistors V1 and V2 to supply
voltage rating. SMD inductivities
conduct full motor coil current.
27R
4n7
50V
27R
4n7
50V
470pF
100V
27R
4n7
50V
470pF
100V
27R
Optional snubbers
eliminate ringing of
inductivity and capacitor.
(Example values only)
BRB
R
SA
BRA
100nF
16V
R
SB
100nF
16V
Figure 3.10 Simple ESD enhancement and more elaborate motor output protection