Datasheet

78K0/Ix2 CHAPTER 23 REGULATOR
R01UH0010EJ0500 Rev.5.00 644
Feb 28, 2012
CHAPTER 23 REGULATOR
23.1 Regulator Overview
The 78K0/Ix2 microcontrollers contain a circuit for operating the device with a constant voltage. At this time, in order to
stabilize the regulator output voltage, connect the REGC pin to V
SS via a capacitor (0.47 to 1  F). However, when using
the STOP mode that has been entered since operation of the internal high-speed oscillation clock and external main
system clock, 0.47
 F is recommended. Also, use a capacitor with good characteristics, since it is used to stabilize
internal voltage.
The regulator output voltage is normally 2.4 V (TYP.), and in the low power consumption mode, 2.0 V (TYP.).
23.2 Registers Controlling Regulator
(1) Regulator mode control register (RMC)
This register sets the output voltage of the regulator.
RMC is set with an 8-bit memory manipulation instruction.
Reset input sets this register to 00H.
Figure 23-1. Format of Regulator Mode Control Register (RMC)
Address: FF3DH After reset: 00H R/W
Symbol 7 6 5 4 3 2 1 0
RMC
RMC[7:0] Control of output voltage of regulator
56H
Low power consumption mode (fixed to 2.0 V)
00H
Normal power mode (fixed to 2.4 V)
Other than above
Setting prohibited
Cautions 1. To change the RMC register setting value from 56H to 00H and use a CPU operating
frequency of 5 MHz or more, change the PCC and RCM registers when 10  s or more has
elapsed after the RMC register was set.
2. When using the setting fixed to the low power consumption mode, the RMC register can be
used in the following cases.
<When X1 clock is selected as the CPU clock> f
X  5 MHz and fCPU  5 MHz
<When the high-speed internal oscillation clock or external input clock are selected for the
CPU clock> f
CPU  5 MHz
3. When using the PLL, set RMC to 00H.
4. When transitioning to the STOP mode, it is possible to achieve low power consumption by
setting RMC = 56H.