PD70F3559 datasheet(28/85 Pages) RENESAS

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R01DS0142ED0100

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

External clock input is prohibited.

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

high

16 < fMOSC ≤ 20 MHz

medium

8 < fMOSC ≤ 16 MHz

low

4 < fMOSC≤ 8 MHz

very low

4 MHz

Parameter

Symbol

Condition

Ratings

Unit

Min

Typ

Max

MainOSC frequency

fMOSC

MHz

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