RX230 Datasheet, PDF (162/177 Pages) Renesas Technology Corp – 54-MHz 32-bit RX MCUs, built-in FPU, 88.56 DMIPS, up to 512-KB flash memory

RX230 Group, RX231 Group
5. Electrical Characteristics
5.15 Usage Notes
5.15.1 Connecting VCL Capacitor and Bypass Capacitors
This MCU integrates an internal voltage-down circuit, which is used for lowering the power supply voltage in the
internal MCU automatically to the optimum level. A 4.7-μF capacitor needs to be connected between this internal
voltage-down power supply (VCL pin) and the VSS pin. Figure 5.79 to Figure 5.81 shows how to connect external
capacitors. Place an external capacitor close to the pins. Do not apply the power supply voltage to the VCL pin.
Insert a multilayer ceramic capacitor as a bypass capacitor between each pair of the power supply pins. Implement a
bypass capacitor as closer to the MCU power supply pins as possible. Use a recommended value of 0.1 μF as the
capacitance of the capacitors. For the capacitors related to crystal oscillation, see section 9, Clock Generation Circuit
in the User’s Manual: Hardware. For the capacitors related to analog modules, also see section 43, 12-Bit A/D
Converter (S12ADE) in the User’s Manual: Hardware.
For notes on designing the printed circuit board, see the descriptions of the application note, the Hardware Design Guide
(R01AN1411EJ). The latest version can be downloaded from the Renesas Electronics website.
R01DS0261EJ0110 Rev.1.10
Oct 30, 2015
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