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7.9
Flash Memory and Power-Down States
There are three flash memory operating states in user mode:
(1) Normal operating mode: The flash memory can be read and written to at high speed.
(2) Power-down mode: Part of the power supply circuitry is halted, and the flash memory can be
read when the LSI is operating in the subactive mode.
(3) Standby mode: When the LSI transits to standby mode, all flash memory circuits are halted,
and the flash memory cannot be read or written to.
Table 7.10 shows the correspondence between the operating states of the LSI and the flash
memory.
The flash memory is transited to power-down mode if the LSI is transited to the subactive mode
while the PDWND bit in FLPWCR is cleared.
When the flash memory is in a power-down state or in standby mode, part or all of the internal
power supply circuitry is halted. Therefore, a power supply circuit stabilization period must be
provided when returning to normal operation. When the flash memory returns to its normal
operating state from a power-down state, bits STS2 to STS0 in SBYCR must be set to provide a
wait time of at least 20 µs including when using an external clock.
Table 7.10 Flash Memory Operating States
LSI Operating State
Active mode
Subactive mode
Sleep mode
Subsleep mode
Standby mode
7.10
Flash Memory Programmer Mode
Programs and data can be written and erased in programmer mode as well as in the on-board
programming modes. In programmer mode, flash memory read mode, auto-program mode, auto-
erase mode, and status read mode are supported. In auto-program mode, auto-erase mode, and
status read mode, a status polling procedure is used, and in status read mode, detailed internal
signals are output after execution of an auto-program or auto-erase operation.
122
When PDWND = 0 (Initial value)
Normal mode
Power-down mode
Normal mode
Standby mode
Standby mode
Flash Memory Operating State
When PDWND = 1
Normal mode
Normal mode
Normal mode
Standby mode
Standby mode
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