Hitachi H8/3692 ユーザーズマニュアル

Rev. 1.0, 07/01, page 273 of 372

Section 18   Power Supply Circuit

This LSI incorporates an internal power supply step-down circuit. Use of this circuit enables the
internal power supply to be fixed at a constant level of approximately 3.0 V, regardless of the
voltage of the power supply connected to the external V

CC

 pin. As a result, the current consumed

when an external power supply is used at 3.0 V or above can be held down to virtually the same
low level as when used at approximately 3.0 V. If the external power supply is 3.0 V or below, the
internal voltage will be practically the same as the external voltage. It is, of course, also possible
to use the same level of external power supply voltage and internal power supply voltage without
using the internal power supply step-down circuit.

Connect the external power supply to the V

CC

 pin, and connect a capacitance of approximately 0.1

µF between V

CL

 and V

SS

, as shown in figure 18-1. The internal step-down circuit is made effective

simply by adding this external circuit. In the external circuit interface, the external power supply
voltage connected to V

CC

 and the GND potential connected to V

SS

 are the reference levels. For

example, for port input/output levels, the V

CC

 level is the reference for the high level, and the V

SS

level is that for the low level. The A/D converter analog power supply is not affected by internal
step-down processing.

V

CL

V

SS

Internal

logic

Step-down circuit

Internal
power
supply

Stabilization
capacitance
(approx. 0.1 

µ

F)

V

CC

V

CC 

= 3.0 to 5.5 V

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