H8SSLASH2214 datasheet(658/936 Pages) RENESAS

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Section 15 ROM

Rev.4.00 Sep. 18, 2008 Page 598 of 872

REJ09B0189-0400

15.14.1

Note on Power-Down States

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 100 µs

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

15.15

Flash Memory Programming and Erasing Precautions

Precautions concerning the use of on-board programming mode, the RAM emulation function, and

PROM mode are summarized below.

(1) Use the specified voltages and timing for programming and erasing

Applied voltages in excess of the rating can permanently damage the device. Use a PROM

programmer that supports the Renesas microcomputer device type with 256-kbyte on-chip flash

memory (FZTAT256V3A).

Do not select the HN27C4096 setting for the PROM programmer, and only use the specified

socket adapter. Failure to observe these points may result in damage to the device.

(2) Powering on and off (See figures 15.29 to 15.31)

Do not apply a high level to the FWE pin until V

CC has stabilized. Also, drive the FWE pin low

before turning off V

CC.

When applying or disconnecting V

CC power, fix the FWE pin low and place the flash memory in

the hardware protection state.

The power-on and power-off timing requirements should also be satisfied in the event of a power

failure and subsequent recovery.

(3) FWE application/disconnection (See figures 15.29 to 15.31)

FWE application should be carried out when MCU operation is in a stable condition. If MCU

operation is not stable, fix the FWE pin low and set the protection state.

The following points must be observed concerning FWE application and disconnection to prevent

unintentional programming or erasing of flash memory:

• Apply FWE when the V

CC voltage has stabilized within its rated voltage range.

• In boot mode, apply and disconnect FWE during a reset.

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