參數(shù)資料
型號: 7544
英文描述: 3.3V LDO POSITVE VOLTAGE REGULATOR 2% TOL.
中文描述: 7544Group數(shù)據(jù)表數(shù)據(jù)表503K/JUN.25.03
文件頁數(shù): 34/54頁
文件大?。?/td> 503K
代理商: 7544
Rev.1.02 2003.06.25 page 34 of 53
7544 Group
PRELIMINARY
Notice: This is not a final specification.
Some parametric limits are subject to change.
Fig. 42 Structure of CPU mode register
(1) Oscillation control
Stop mode
When the STP instruction is executed, the internal clock
φ
stops at
an
H
level and the X
IN
oscillator stops. At this time, timer 1 is set
to
01
16
and prescaler 1 is set to
FF
16
when the oscillation sta-
bilization time set bit after release of the STP instruction is
0
. On
the other hand, timer 1 and prescaler 1 are not set when the
above bit is
1
. Accordingly, set the wait time fit for the oscillation
stabilization time of the oscillator to be used. Single selected by
the timer 1 count source selection bit is connected to the input of
prescaler 1. When an external interrupt is accepted, oscillation is
restarted but the internal clock
φ
remains at
H
until timer 1
underflows. As soon as timer 1 underflows, the internal clock
φ
is
supplied. This is because when a ceramic/qruartz-crystal oscillator
is used, some time is required until a start of oscillation. In case
oscillation is restarte______
ply an
L
level to the RESET pin while oscillation becomes stable.
Also, the STP instruction cannot be used while CPU is operating
by a ring oscillator.
Wait mode
If the WIT instruction is executed, the internal clock
φ
stops at an
H
level, but the oscillator does not stop. The internal clock re-
starts if a reset occurs or when an interrupt is received. Since the
oscillator does not stop, normal operation can be started immedi-
ately after the clock is restarted. To ensure that interrupts will be
received to release the STP or WIT state, interrupt enable bits
must be set to
1
before the STP or WIT instruction is executed.
I
Notes on clock generating circuit
For use with the oscillation stabilization set bit after release of the
STP instruction set to
1
, set values in timer 1 and prescaler 1 af-
ter fully appreciating the oscillation stabilization time of the
oscillator to be used.
Switch of ceramic/quartz-crystal and RC oscillations
After releasing reset the operation starts by starting a built-in ring
oscillator. Then, a ceramic/qruartz-crystal oscillation or an RC os-
cillation is selected by setting bit 5 of the CPU mode register.
Double-speed mode
When a ceramic/quartz-crystal oscillation is selected, a double-
speed mode can be used. Do not use it when an RC oscillation is
selected.
CPU mode register
Bits 5, 1 and 0 of CPU mode register are used to select oscillation
mode and to control operation modes of the microcomputer. In or-
der to prevent the dead-lock by error-writing (ex. program
run-away), these bits can be rewritten only once after releasing re-
set. After rewriting it is disable to write any data to the bit. (The
emulator MCU
M37544RSS
is excluded.)
Also, when the read-modify-write instructions (SEB, CLB) are ex-
ecuted to bits 2 to 4, 6 and 7, bits 5, 1 and 0 are locked.
Clock division ratio, X
IN
oscillation control, ring oscillator control
The state transition shown in Fig. 46 can be performed by setting
the clock division ratio selection bits (bits 7 and 6), X
IN
oscillation
control bit (bit 4), ring oscillator oscillation control bit (bit 3) of CPU
mode register. Be careful of notes on use in Fig. 46.
Oscillation mode selection bit (Note 1)
0 : Ceramic/quartz-crystal oscillation
1 : RC oscillation
CPU mode register
(CPUM: address 003B
16
, initial value: 80
16
)
Stack page selection bit
1 : 1 page
Clock division ratio selection bits
φ
) = f(X
IN
)/2 (High-speed mode)
0 1 : f(
) = f(X
IN
)/8 (Middle-speed mode)
1 0 : applied from ring oscillator
1 1 : f(
) = f(X
IN
) (Double-speed mode)(Note 2)
Ring oscillator oscillation control bit
IN
oscillation control bit
X
Processor mode bits (Note 1)
0 0 Single-chip mode
0 1
1 0
Not available
b7 b0
2:
These bits are used only when a ceramic
/quartz-crystal
oscillation is selected.
Do not use these when an RC oscillation is selected.
Note 1:
The bit can be rewritten only once after releasing reset. After rewriting
it is disable to write any data to the bit. However, by reset the bit is
initialized and can be rewritten, again.
(It is not disable to write any data to the bit for emulator MCU
M37544RSS
.)
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