HD64F38024HV Datasheet, PDF (469/684 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip Microcomputer H8 Family/H8/300L Super Low Power Series

Section 15 Power Supply Circuit (H8/38124 Group Only)
Section 15 Power Supply Circuit
(H8/38124 Group Only)
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 VCC 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.
15.1 When Using Internal Power Supply Step-Down Circuit
Connect the external power supply to the VCC pin, and connect a capacitance of approximately 0.1
µF between CVCC and VSS, as shown in figure 15.1. 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 VCC and the GND potential connected to VSS are the reference levels.
For example, for port input/output levels, the VCC level is the reference for the high level, and the
VSS level is that for the low level. The A/D converter analog power supply is not affected by the
internal step-down circuit.
V_CC
V_CC = 2.7 to 5.5 V
Step-down circuit
CV_CC
Internal
logic
Internal
power
supply
Stabilization
capacitance
(approx. 0.1 µF)
V_SS
Figure 15.1 Power Supply Connection when Internal Step-Down Circuit is Used
PSCKT00A_000020020200
Rev. 8.00 Mar. 09, 2010 Page 447 of 658
REJ09B0042-0800