Datasheet
RL78/L12    CHAPTER 19 STANDBY FUNCTION 
R01UH0330EJ0200 Rev.2.00      739 
Dec 13, 2013 
Table 19-2. Operating Statuses in STOP Mode 
STOP Mode Setting 
Item 
When STOP Instruction Is Executed While CPU Is Operating on Main System Clock 
When CPU Is Operating on 
High-Speed On-Chip 
Oscillator Clock (f
IH) 
When CPU Is Operating on 
X1 Clock (f
X) 
When CPU Is Operating on 
External Main System Clock 
(f
EX) 
System clock  Clock supply to the CPU is stopped 
 Main system clock fIH Stopped 
 fX 
 fEX 
 Subsystem clock fXT  Status before STOP mode was set is retained 
 fEXS 
 fIL  Set by bits 0 (WDSTBYON) and 4 (WDTON) of option byte (000C0H), and WUTMMCK0 bit of 
subsystem clock supply mode control register (OSMC) 
• WUTMMCK0 = 1: Oscillates 
• WUTMMCK0 = 0 and WDTON = 0: Stops 
• WUTMMCK0 = 0, WDTON = 1, and WDSTBYON = 1: Oscillates 
• WUTMMCK0 = 0, WDTON = 1, and WDSTBYON = 0: Stops 
CPU Operation stopped 
Code flash memory 
Data flash memory  Operation stopped 
RAM Operation stopped 
Port (latch)  Status before STOP mode was set is retained 
Timer array unit  Operation disabled 
Real-time clock (RTC)  Operable 
12-bit interval timer 
Watchdog timer  See CHAPTER 10 WATCHDOG TIMER 
Clock output/buzzer output  Operates when the subsystem clock is selected as the clock source for counting and the 
RTCLPC bit is 0 (operation is disabled when a clock other than the subsystem clock is selected 
and the RTCLPC bit is not 0). 
A/D converter  Wakeup operation is enabled (switching to the SNOOZE mode) 
Serial array unit (SAU) 
Wakeup operation is enabled only for CSI00 and UART0 (switching to the SNOOZE mode) 
Operation is disabled for anything other than CSI00 and UART0 
Serial interface (IICA) 
Wakeup by address match operable 
LCD driver/controller  Operable (However, this depends on the status of the clock selected as the LCD source clock: 
operation is possible if the selected clock is operating, but operation will stop if the selected 
clock is stopped.) 
Multiplier and divider/multiply-
accumulator 
Operation disabled 
DMA controller 
Power-on-reset function  Operable 
Voltage detection function 
External interrupt 
Key interrupt function 
CRC 
operation 
function 
High-speed CRC 
Operation stopped 
General-purpose 
CRC 
RAM parity error detection 
function 
RAM guard function 
SFR guard function 
Illegal-memory access 
detection function 
Remark Operation stopped:   Operation is automatically stopped before switching to the STOP mode. 
 Operation disabled:   Operation is stopped before switching to the STOP mode. 
 f
IH:  High-speed on-chip oscillator clock  fIL:  Low-speed on-chip oscillator clock 
 f
X: X1 clock  fEX:  External main system clock 
 f
XT: XT1 clock  fEXS:  External subsystem clock 










