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19.12
Power-Down States for Flash Memory
In user mode, the flash memory will operate in either of the following states:
• Normal operating mode
The flash memory can be read and written to.
• Standby mode
All flash memory circuits are halted.
Table 19.8 shows the correspondence between the operating modes of this LSI and the flash
memory. When the flash memory returns to normal operation from a power-down state, a power
supply circuit stabilization period is needed. When the flash memory returns to its normal
operating state, bits STS2 to STS0 in SBYCR must be set to provide a wait time of at least 100 µs,
even when the external clock is being used and an oscillation stabilization time is not necessary.
Table 19.8 Flash Memory Operating States
LSI Operating State
Active mode
Sleep mode
Standby mode
19.13
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 Hitachi 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
Do not apply a high level to the FWE pin until VCC has stabilized. Also, drive the FWE pin
low before turning off VCC. When applying or disconnecting VCC 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.
Flash Memory Operating State
Normal operating mode
Normal operating mode
Standby mode
(Before entering to the normal operation mode, wait time of at least
100 µs is required.)
Rev. 3.0, 10/02, page 589 of 686
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