Section 20 Power Supply Circuit
Section 20 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, 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.
20.1
Power Supply Connection of 5.0-V-Specification Microcontrollers
Connect the external power supply to the VCC pin, and connect a capacitor of approximately 0.1 µF
between VCL and VSS, as shown in figure 20.1. 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.
VCC
VCC = 4.5 to 5.5 V
Step-down circuit
VCL
Stabilization
capacitor (approx. 0.1 µF)
Internal
power
supply
Internal
logic
VSS
Figure 20.1 Power Supply Connection of 5.0-V-Specification Microcontrollers
PSCKT00A_000020020200
Rev. 3.00 Sep. 10, 2007 Page 393 of 528
REJ09B0216-0300
RENESAS [ RENESAS TECHNOLOGY CORP ]
