908E626_09 Datasheet, PDF (35/44 Pages) Freescale Semiconductor, Inc – Integrated Stepper Motor Driver with Embedded MCU and LIN Serial Communication

TYPICAL APPLICATIONS
FACTORY TRIMMING AND CALIBRATION
EMC/EMI RECOMMENDATIONS
This paragraph gives some device specific
recommendations to improve EMC/EMI performance.
Further generic design recommendations can be e.g. found
on the Freescale web site www.freescale.com.
VSUP pins (VSUP1:VSUP3)
Its recommended to place a high quality ceramic
decoupling capacitor close to the VSUP pins to improve
EMC/EMI behavior.
MCU digital supply pins (EVDD and EVSS)
Fast signal transitions on MCU pins place high, short
duration current demands on the power supply. To prevent
noise problems, take special care to provide power supply
bypassing at the MCU. It is recommended that a high quality
ceramic decoupling capacitor be placed between these pins.
MCU analog supply pins (VREFH, VDDA and VREFL,
VSSA)
LIN pin
For DPI (Direct Power Injection) and ESD (Electrostatic
Discharge) its recommended to place a high quality ceramic
decoupling capacitor near the LIN pin. An additional varistor
will further increase the immunity against ESD. A ferrite in the
LIN line will suppress some of the noise induced.
Voltage regulator output pins (VDD and AGND)
To avoid noise on the analog supply pins its important to
take special care on the layout. The MCU digital and analog
supplies should be tied to the same potential via separate
traces and connected to the voltage regulator output.
Figure 18 and Figure 19 show the recommendations on
schematics and layout level and Table 11 indicates
recommended external components and layout
considerations.
Use a high quality ceramic decoupling capacitor to
stabilize the regulated voltage.
VSUP
D1
+
C1
C2
L1
LIN
V1
C5
VSUP1
VSUP2
VSUP3
LIN
VDD
VSS
VREFH
VDDA
EVDD
C3
C4
MM908E625
EVSS
VSSA
GND1
VREFL
GND2
Figure 18. EMC/EMI Recommendations
Analog Integrated Circuit Device Data
Freescale Semiconductor
908E626
35