Datasheet

TMC5041 DATASHEET (Rev. 1.13 / 2017-MAY-16) 14
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3.3.2 Internal Regulator Bridged
In case a clean external 5V supply is available, it can be used for complete supply of analog and
digital part (Figure 3.4). The circuit will benefit from a well regulated supply, e.g. when using a +/-1%
regulator. A precise supply guarantees increased motor current precision, because the voltage at
5VOUT directly is the reference voltage for all internal units of the driver, especially for motor current
control. For best performance, the power supply should have low ripple to give a precise and stable
supply at 5VOUT pin with remaining ripple well below 5mV. Some switching regulators have a higher
remaining ripple, or different loads on the supply may cause lower frequency ripple. In this case,
increase capacity attached to 5VOUT. In case the external supply voltage has poor stability or low
frequency ripple, this would affect the precision of the motor current regulation as well as add
chopper noise.
5V Voltage
regulator
+5V
5VOUT
VSA
4.7µ
VCC
470n
10R
Well-regulated, stable
supply, better than +-5%
Figure 3.4 Using an external 5V supply to bypass internal regulator
3.4 Optimizing Analog Precision
The 5VOUT pin is used as an analog reference for operation of the TMC5041. Performance will degrade
when there is voltage ripple on this pin. Most of the high frequency ripple in a TMC5041 design
results from the operation of the internal digital logic. The digital logic switches with each edge of
the clock signal. Further, ripple results from operation of the charge pump, which operates with
roughly 1 MHz and draws current from the VCC pin. In order to keep this ripple as low as possible, an
additional filtering capacitor can be put directly next to the VCC pin with vias to the GND plane giving
a short connection to the digital GND pins (pin 6 and pin 34). Analog performance is best, when this
ripple is kept away from the analog supply pin 5VOUT, using an additional series resistor of 2.2 . The
voltage drop on this resistor will be roughly 100 mV (I
VCC
* R).
5V Voltage
regulator
charge pump
VCP
22n
100n
+V
M
5VOUT
VSA
4.7µ
VCC
100n
470n
CPI
CPO
GNDA
2R2
Figure 3.5 RC-Filter on VCC for reduced ripple
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. It is best practice to avoid ESD events by attaching all