ST92141 STMicroelectronics, ST92141 Datasheet - Page 68

• Manufacturer Part Number: ST92141
• Description: 8/16-bit Mcu For 3-phase Ac Motor Control
• Manufacturer: STMicroelectronics

ST92141 - RESET AND CLOCK CONTROL UNIT (RCCU)
Figure 30. Example of Low Power Mode programming
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1
continued
Main code execution
Wait for the
PLL locking
(LOCK->1)
Interrupt
Interrupt
Routine
WAIT
WAIT
PROGRAM FLOW
CSU_CKSEL
WFI_CKSEL
User’s Program
CSU_CKSEL<- 1
CSU_CKSEL = 0
DX2-0
CKAF_SEL <- 0
User’s Program
XTSTOP
XTSTOP = 0
LPOWFI
XTSTOP
MX(1:0)
WFI status
DIV2
Begin
WFI
End
000
1
00
1
1
0
1
1
COMMENTS
Low Power Mode enabled
Multiplier divider’s factor set
CK_AF clock selected when WFI
To stop PLL and Xtal when
a WFI occurs
No code is executed until
the system clock
The system CK
switches to Xtal
to 1, and PLL turned ON
PLL is
system clock source
Interrupt served
To restart Xtal and PLL
Wait For Interrupt
an interrupt is requested
restart the PLL quickly
The PLL is locked
and becomes the
system clock
Quartz divided by 2
PLL multiply factor
while the CK_AF is
Xtal is selected to
SET UP AFTER RESET PHASE:
fixed to 10.
** T
* T
1
2
= PLL lock-in time
= Quartz oscillator start-up time
SYSTEM CLOCK FREQUENCY
F
Q
=5 MHz, V
cc
T
T
=5 V and T=25°C
1
1
*
*
T
2
**
CK_AF/16
2.5 MHz
2.5 MHz
CK_AF
25 MHz
25 MHz