H8S2172 Datasheet, PDF (556/572 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2100 Series

18.5 Use Note (Internal Voltage Step Down)
The H8S/2170 F-ZTAT have a voltage step down circuit that automatically lowers the power
supply voltage, inside the microcomputer, to an adequate level. A capacitor (one 0.1-µF capacitor)
should be connected between the VCL pin (a pin for internal voltage step down circuit) and VSS
pin to stabilize the internal voltage. Figure 18.29 shows how to connect the capacitor. Do not
connect the V_CC power-supply to the VCL pin. Doing so could permanently damage the LSI.
(Connect the V_CC power-supply to the V_CC pin, in the usual way.)
An external capacitor to
stabilize the internal voltage
One 0.1-µF capacitor
VCL
VSS
VDo not connect the Vcc power-supply to the VCL pin.
If connected, the LSI may be permanently damaged.
Connect the VCC power-Supply to the other Vcc pin in the usual way.
Use a multilayer ceramic capacitor (one 0.1-µF capacitor) for this circuit,
and place it/them near the VCL pin.
Figure 18.29 VCL Capacitor Connection Method
Rev. 2.00, 03/04, page 522 of 534