SH7708 datasheet(202/633 Pages) RENESAS

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184

9.11

Notes on Board Design

When Using an External Crystal Resonator: Place the crystal resonator, capacitors CL1 and

CL2, and damping resistor R close to the EXTAL and XTAL pins. To prevent induction from

interfering with correct oscillation, use a common grounding point for the capacitors connected to

the resonator, and do not locate a wiring pattern near these components.

Note: The values for CL1, CL2, and the damping resistance should be determined after

consultation with the crystal manufacturer.

XTAL

EXTAL

SH7708R

CL2

CL1

Avoid crossing

signal lines

Figure 9.8 Points for Attention when Using Crystal Resonator

Decoupling Capacitors: As far as possible, insert a laminated ceramic capacitor of 0.01 to 0.1 µF

as a passive capacitor for each V

SS/VCC pair. Mount the passive capacitors as close as possible to

the LSI power supply pins, and use components with a frequency characteristic suitable for the

LSI operating frequency, as well as a suitable capacitance value.

Digital system V

SS/VCC pairs: 6-7, 17-18, 19-20, 30-31, 41-42, 49-50, 54-55, 59-60, 68-69,

82-81,83, 100-102, 115-116, 121-122, 127-128, 144-139

On-chip oscillator V

SS/VCC pairs: 73-75, 76-78, 138-135

When Using a PLL Oscillator Circuit: Keep the wiring from the PLL V

CC and VSS connection

pattern to the power supply pins short, and make the pattern width large, to minimize the

inductance component. Ground the oscillation stabilization capacitors C1 and C2 to V

SS (PLL1)

and V

SS (PLL2), respectively. Place C1 and C2 close to the CAP1 and CAP2 pins and do not

locate a wiring pattern in the vicinity. In clock mode 7, connect the EXTAL pin to V

CC or VSS and

leave the XTAL pin open.

SH7708 数据表(PDF) 202 Page - Renesas Technology Corp

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