SH7101 datasheet(92/560 Pages) RENESAS

92 / 560 page

Section 4 Clock Pulse Generator

Rev.1.00 Sep. 18, 2008 Page 58 of 522

REJ09B0069-0100

When using a crystal resonator, place the crystal resonator and its load capacitors as close as

possible to the XTAL and EXTAL pins. Do not route any signal lines near the oscillator circuitry

as shown in figure 4.5. Otherwise, correct oscillation can be interfered by induction.

CL2

Signal A Signal B

This LSI

CL1

XTAL

EXTAL

Avoid

Figure 4.5 Cautions for Oscillator Circuit System Board Design

A circuitry shown in figure 4.6 is recommended as an external circuitry around the PLL. Place

oscillation stabilization capacitor C1 close to the PLLCAP pin, and ensure that no other signal

lines cross this line. Separate PLLVCL and PLLVSS circuit against VCC and VSS circuit from the

board power-supply source, and be sure to insert bypass capacitors CB and CPB close to the pins.

PLLCAP

PLLVCL

PLLVSS

VCC

VSS

C1: 470 pF

R1: 3k

CPB = 0.47

μF*

CB = 0.47

μF*

(Values are recommended values.)

Note: * CB and CPB are laminated ceramic type.

Figure 4.6 Recommended External Circuitry Around the PLL

Electromagnetic waves are radiated from an LSI in operation. This LSI has an electromagnetic

peak in the harmonics band whose primary frequency is determined by the lower frequency

between the system clock (

φ) and peripheral clock (Pφ). For example, when φ = 50 MHz and Pφ =

40 MHz, the primary frequency is 40 MHz. If this LSI is used adjacent to a device sensitive to

electromagnetic interference, e.g. FM/VHF band receiver, a printed circuit board of more than

four layers with planes exclusively for system ground is recommended.

SH7101 Datasheet(PDF) 92 Page - Renesas Technology Corp