Datasheet
RL78/L12    CHAPTER 5 CLOCK GENERATOR 
R01UH0330EJ0200 Rev.2.00      140 
Dec 13, 2013 
Figure 5-5. Format of Oscillation Stabilization Time Counter Status Register (OSTC) 
Address: FFFA2H After reset: 00H R 
Symbol 7 6 5 4 3 2 1 0   
OSTC MOST
8 
MOST
9 
MOST
10 
MOST
11 
MOST
13 
MOST
15 
MOST
17 
MOST
18 
MOST
8 
MOST
9 
MOST
10 
MOST
11 
MOST
13 
MOST
15 
MOST
17 
MOST
18 
Oscillation stabilization time status 
 fX = 10 MHz  fX = 20 MHz
0 0 0 0 0 0 0 0 2
8
/fX max. 25.6 
μ
s max.  12.8 
μ
s max.
1 0 0 0 0 0 0 0 2
8
/fX min. 25.6 
μ
s min.  12.8 
μ
s min.
1 1 0 0 0 0 0 0 2
9
/fX min. 51.2 
μ
s min.  25.6 
μ
s min.
1 1 1 0 0 0 0 0 2
10
/fX min. 102.4 
μ
s min.  51.2 
μ
s min.
1 1 1 1 0 0 0 0 2
11
/fX min. 204.8 
μ
s min.  102.4 
μ
s min.
1 1 1 1 1 0 0 0 2
13
/fX min. 819.2 
μ
s min.  409.6 
μ
s min.
1 1 1 1 1 1 0 0 2
15
/fX min. 3.27 ms min.  1.64 ms min.
1 1 1 1 1 1 1 0 2
17
/fX min. 13.11 ms min. 6.55 ms min.
1 1 1 1 1 1 1 1 2
18
/fX min. 26.21 ms min. 13.11 ms min.
Cautions 1.  After the above time has elapsed, the bits are set to 1 in order from the MOST8 bit 
and remain 1. 
  2.  The oscillation stabilization time counter counts up to the oscillation stabilization 
time set by the oscillation stabilization time select register (OSTS). 
    In the following cases, set the oscillation stabilization time of the OSTS register to 
the value greater than the count value which is to be checked by the OSTC register. 
• If the X1 clock starts oscillation while the high-speed on-chip oscillator clock or 
subsystem clock is being used as the CPU clock. 
• If the STOP mode is entered and then released while the high-speed on-chip 
oscillator clock is being used as the CPU clock with the X1 clock oscillating. 
(Note, therefore, that only the status up to the oscillation stabilization time set by 
the OSTS register is set to the OSTC register after the STOP mode is released.) 
  3.  The X1 clock oscillation stabilization wait time does not include the time until clock 
oscillation starts (“a” below). 
STOP mode release
X1 pin voltage 
waveform
a
Remark f
X: X1 clock oscillation frequency 










