TMC2100 DATASHEET (Rev. 1.07 / 2017-MAY-15)
15
4.7 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 of several kV. 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 application PCB circuitry and thus reduce electromagnetic emission. A more elaborate scheme
uses LC filters to de-couple the driver outputs from the motor connector. Varistors in between of the
coil terminals eliminate coil overvoltage caused by live plugging. Optionally protect all outputs by a
varistor against ESD voltage.
470pF
100V
50Ohm
100MHz
@
V1A
V1B
OA1
OA2
OA1
OA2
N
N
V1
Full Bridge
A
stepper
motor
Full Bridge
A
stepper
motor
S
S
50Ohm
100MHz
@
470pF
100V
470pF
100V
470pF
100V
BRA
100nF
16V
Driver
Driver
RSA
470pF
100V
50Ohm
100MHz
@
V2A
V2B
OB1
OB2
OB1
OB2
V2
Full Bridge
B
Full Bridge B
50Ohm
100MHz
@
Varistors V1 and V2 protect
against inductive motor coil
overvoltage.
470pF
100V
470pF
100V
470pF
100V
BRB
Fit varistors to supply voltage
rating. SMD inductivities
conduct full motor coil
current.
V1A, V1B, V2A, V2B:
Optional position for varistors
in case of heavy ESD events.
100nF
16V
RSB
Figure 4.7 Simple ESD enhancement and more elaborate motor output protection
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TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
