Datasheet

TMC5031 DATASHEET (Rev. 1.11 / 2016-APR-28) 14
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3.4 Optimizing Analog Precision
The 5VOUT pin is used as an analog reference for operation of the TMC5031. Performance will degrade
when there is voltage ripple on this pin. Most of the high frequency ripple in a TMC5031 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 Ω to
3.3 Ω. 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 3.6 Adding an RC-Filter on VCC for reduced ripple