RX23T Datasheet, PDF (88/98 Pages) Renesas Technology Corp – 40-MHz 32-bit RX MCUs, built-in FPU, 65.6 DMIPS

RX23T Group
5. Electrical Characteristics
5.10 Usage Notes
5.10.1 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 to adjust automatically to the optimum level. A 4.7-μF capacitor needs to be connected between this
internal voltage-down power supply (VCL pin) and VSS pin. Figure 5.56 to Figure 5.58 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 to the MCU power supply pins as close 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 29, 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 "Hardware Design Guide"
(R01AN1411EJ). The latest version can be downloaded from Renesas Electronics Website.
R01DS0248EJ0110 Rev.1.10
Jan 13, 2016
Page 88 of 98