SH7641 Datasheet, PDF(202/1036 Page) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family / SH7641 Series

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SH7641 Datasheet, PDF (202/1036 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family / SH7641 Series

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Section 4 Clock Pulse Generator (CPG)

4.6 Notes on Board Design

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

CL2, and feedback resistor R1 as close to the XTAL and EXTAL pins as possible. In addition, to

minimize induction and thus obtain oscillation at the correct frequency, the capacitors to be

attached to the resonator must be grounded to the same ground. Do not bring wiring patterns close

to these components.

Signal lines prohibited

CL1

CL2

Rl

EXTAL

XTAL

This LSI

Reference value

CL1 = 10 to 33 pF

CL2 = 10 to 33 pF

Rl = 1Mâ¦

Note:

The values for CL1, CL2, and

the damping resistance RI

should be determined after

consultation with the crystal

resonator manufacturer.

Figure 4.2 Note on Using a Crystal Resonator

Notes on Using External Clocks: When external clocks are input from the EXTAL pin, leave the

XTAL pin open. In order to prevent a malfunction due to the reflection noise caused in a signal

line which connected to XTAL pin, cut this signal line as short as possible.

Notes on Bypass Capacitor: A multilayer ceramic capacitor must be inserted for each pair of Vss

and Vcc as a bypass capacitor. The bypass capacitor must be inserted as close as possible to the

power supply pins of the LSI. Note that the capacitance and frequency characteristics of the

bypass capacitor must be appropriate for the operating frequency of the LSI.

â¢ A pair of Vss and VCC for the input/output power supply

C1 to D1, M4 to M3, V1 to W1, U7 to V7, U12 to V12, Y18 to Y19, M19 to M18, H17 to

H18, C20 to B20, A18 to A17, D14 to C14, D13 to C13, D8 to C8, A3 to A2

â¢ A pair of Vss and Vcc for the digital modules

F3 to F4, K3 to K4, U4 to T4, V6 to U6, V10 to U10, U17 to U16, R18 to R17, L18 to L17,

D17 to E17, C15 to D15, C11 to D11, D4 to D5

â¢ A pair of Vss and Vcc for the on-chip oscillator

K20 to K17, K18 to J20

Rev. 4.00 Sep. 14, 2005 Page 152 of 982

REJ09B0023-0400

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