Flash Memory And Power-Down States; Note On Power-Down States - Renesas H8S/2633 Series Hardware Manual

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Flash Memory and Power-Down States

In addition to its normal operating state, the flash memory has power-down states in which power

consumption is reduced by halting part or all of the internal power supply circuitry.

There are three flash memory operating states:

(1) Normal operating mode: The flash memory can be read and written to.

(2) Power-down mode: Part of the power supply circuitry is halted, and the flash memory can be

read when the H8S/2633 is operating on the subclock.

(3) Standby mode: All flash memory circuits are halted, and the flash memory cannot be read or

States (2) and (3) are flash memory power-down states. Table 22-25 shows the correspondence

between the operating states of the H8S/2633 and the flash memory.

Table 22-25 Flash Memory Operating States

LSI Operating State

High-speed mode

Medium-speed mode

Subactive mode

Subsleep mode

Software standby mode

Hardware standby mode

When the flash memory is in a power-down state, 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

(power supply stabilization time), even if an oscillation stabilization period is not necessary.

Flash Memory Operating State

Normal mode (read/write)

When PDWND = 0: Power-down mode (read-only)

When PDWND = 1: Normal mode (read-only)

Standby mode