Datasheet

TMC2300 DATASHEET (Rev. 1.02 / 2019-NOV-06) 16
www.trinamic.com
3.5 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 may be varied
between 100pF and 470pF. 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 suppressor diodes to GND, or by a diode network as shown.
Full Bridge A
Full Bridge B
stepper
motor
N
S
OA1
OA2
OB1
OB2
Driver
220pF
15V
220pF
25V
220pF
25V
220pF
25V
Full Bridge A
Full Bridge B
stepper
motor
N
S
OA1
OA2
OB1
OB2
Driver
470pF
100V
470pF
100V
50Ohm @
100MHz
50Ohm @
100MHz
50Ohm @
100MHz
50Ohm @
100MHz
Enhanced electromagnetic emission
protection using L/C filter
470pF
100V
470pF
100V
BRB
R
SA
BRA
100nF
10V
R
SB
100nF
10V
High voltage ESD and motor back drive
protection using line protector IC
SRV05-4
+VS
(max. 5V)
Figure 3.5 Simple ESD & EMI enhancement and more elaborate motor output protection
3.6 Very low I/O voltage operation
In cases, where an I/O voltage of 1.8V (or even lower, due to tolerance) is to be used, the VIO
undervoltage threshold level might be too high, to safely release the TMC2300 from reset state. A
simple way to avoid the need for an additional I/O voltage regulator (e.g. 2V type), is to use the
internal 1.8V regulator to self-supply the TMC2300 VIO pin. In order to allow power-up, the voltage on
pin at VIO/NSTDBY has to be forced to min. 1.4V. In order to go back to low power standby, pull it
down to less than 0.6V. A PNP transistor gives a low resistive switch to supply VIO.
100n
1.8VOUT
VIO/
NSTDBY
1.8V Voltage
regulator
100n
Standby
detector
STANDBY
STANDBY
500k
Control Signals
Digital I/O
µC powered with 1.8V +
-10% I/O
voltage
1K
Standby
470R
Powerup
BC858B
Figure 3.6 Additional Circuit for I/O voltage <1.80V