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The V
4181 requires several external passive components for proper operation, which are connected to
R
VDD_PLL as illustrated in Figure 22-1.
Figure 22-1. Example of Connection of PLL Passive Components
Remarks 1. Capacitors C1 and C2 and resistor R are mounted on the printed circuit board.
2. Since the value for the components depends upon the application system, the optimum values
for each system should be decided after repeated experimentation.
It is essential to isolate the analog power and ground for the PLL circuit (VDD_PLL, GND_PLL) from the regular
power and ground (VDD_LOGIC, GND_LOGIC). The following values are an example for each component.
R = 100 Ω
Since the optimum values for the filter components depend upon the application and the system noise
environment, these values should be considered as starting points for further experimentation within your specific
application. In addition, the choke (inductor: L) can be considered for use as an alternative to the resistor (R) for use
in filtering the power supply.
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CHAPTER 22 PLL PASSIVE COMPONENTS
VDD_LOGIC
VDD_PLL
V
4181
R
GND_PLL
GND_LOGIC
C1 = 0.1 µ F
C2 = 1.0 µ F
User's Manual U14272EJ3V0UM
R
C1
C2
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