Section 15 Power Supply Circuit (H8/38124 Group Only); When Using Internal Power Supply Step-Down Circuit - Renesas H8 Series Hardware Manual

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, independently of the
voltage of the power supply connected to the external V
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.
15.1

When Using Internal Power Supply Step-Down Circuit

Connect the external power supply to the V
µF between CV and V
CC
effective simply by adding this external circuit. In the external circuit interface, the external power
supply voltage connected to V
For example, for port input/output levels, the V
V level is that for the low level. The A/D converter analog power supply is not affected by the
SS
internal step-down circuit.
Figure 15.1 Power Supply Connection when Internal Step-Down Circuit is Used
PSCKT00A_000020020200

Section 15 Power Supply Circuit (H8/38124 Group Only)

Section 15 Power Supply Circuit
(H8/38124 Group Only)
, as shown in figure 15.1. The internal step-down circuit is made
SS
and the GND potential connected to V
CC
Step-down circuit
Internal
Internal
power
logic
supply
pin. As a result, the current consumed
CC
pin, and connect a capacitance of approximately 0.1
CC
level is the reference for the high level, and the
CC
V V = 2.7 to 5.5 V
CC CC
CV
CC
Stabilization
capacitance
(approx. 0.1 µF)
V
SS
Rev. 7.00 Mar 10, 2005 page 451 of 652
are the reference levels.
SS
REJ09B0042-0700