Hitachi AP1 Data Book page 283

--------------------------------------------------------------HD614P080S
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GND
Fig. 16 Recommendable Layout of Crystal and Ceramic Filter
• LOW POWER DISSIPATION MODE
The MeV provides two low power dissipation modes, that is,
a Standby mode and a Stop mode. Table 21 shows the function
of the low power dissipation mode, and Fig. 17 shows the
diagram of the mode transition.
Table 21 Low Power Dissipation Mode Function
Condition
Low Power
Instruction Input/
Timer/ Recovering
Dissipation Mode
Oscillator Instruction Register Interrupt
RAM Output
Counter, method
circuit execution Flag function
pin
Serial
Interface
Standby mode
SBY
Active Stop Retained Active Retained
*21
Active
RESET Input,
instruction
Retained
Interrupt request
Stop mode
STOP
Stop
Stop
RESET*11
Stop
Retained
High
Stop
RESET Input
instruction impedance
* 11 STOP mode is released only by MCU Reset. Refer to Table 19 as for the values of the registers and flags after releasing stop mode.
*21 Current flows in I/O Circuit by I/O p,in state at stand-bY mode, because I/O circuit is active.
This current is an addition to stand-by mode power dissipation.
Fig. 17 MCU Operation Mode Transition
• Standby Mode
The SBY instruction puts the MCV into the Standby mode.
In the Standby mode, the oscillator circuit is active and timer/
281
counter and serial interface continue working. On the other
hand, the CPV stops since the clock related to the instruction
execution stops. Registers, RAM and Input/Output pins retain
the state they had just before going into the Standby mode.
The Standby mode is canceled by the MCV reset or interrupt
request. When canceled by the interrupt request, the MCV
becomes an active mode and executes the instruction next to
the SBY instruction_ At this time, if the Interrupt Enable Flag
is "I", the interrupt is executed. If the Interrupt Enable Flag
is "0", the interrupt request is held on and the normal instruc-
tion execution continues.
Fig. 18 shows the flowchart of the Standby Mode .
• Stop Mode
The STOP instruction brings the MCV into the Stop mode.
In this mode the oscillator circuit and every function of the
MCV stop.
The Stop mode is canceled by the MCV reset. At this time,
as shown in Fig. 19, apply the RESET input for more than tRC
to get enough oscillator stabilization time. (Refer to the HAC
CHARACTERISTICS".) After the Stop mode is canceled,
RAM retains the state it had just before going into the Stop
mode after releasing stop mode by MCV reset, the values of the
B register, W register, X/SPX register, Y/SPY register, carry and
serial data register are not guaranteed.