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R01DS0139ED0100

Data Sheet

Chapter 4 Clock generators

The main oscillator amplifier gain for the external resonator can be selected by

MOSCC.MOSCCAMPSEL[1:0]. Thereby it can be adjusted to support a wide

range of frequencies to cope with different external resonators and their

external circuitry.

As an example a typical setting for quartz crystals is shown in Table 4-3

“Typical setting of MOSCC.AMPSEL[1:0] for different quartz crystals

frequencies”.

Note For details to the setting of MOSCC.MOSCCAMPSEL[1:0] please refer to the

user manual.

(1) Main oscillator charactrisitics

Table 4-4 Main oscillator characteristics

Cautions 1. External clock input is prohibited.

2. General guidance for PCB layout:

• Keep the wiring length as short as possible.

• Do not cross the wiring with other signal lines.

• Do not route this circuit close to a signal line with high fluctuating current

flow.

• Always make the ground point of the oscillator capacitor the same

potential as REG0VSS and OSCVSS.

• Do not ground the capacitor to a ground pattern with high current flow.

• Do not tap signals from the oscillator.

4.3.2 Sub-oscillator

A crystal resonator can be connected to the sub clock input pins as shown in

figure 4-2 “Recommended Sub Oscillator Circuit”

Table 4-3 Typical setting of MOSCC.AMPSEL[1:0] for different quartz crystals

frequencies

MOSCC.AMPSEL[

1:0]

Amplification

gain

Typical condition for quartz

crystals

00 high 16 < f

MOSC

 20 MHz

01 medium 8 < f

MOSC

 16 MHz

10 low 4 < f

MOSC

 8 MHz

11 very low 4 MHz

Parameter Symbol Condition

Ratings

Unit

Min Typ Max

MainOSC frequency f

MOSC

4-20MHz

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 77 78

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