HN58V65A Datasheet, PDF(21/27 Page) Hitachi Semiconductor – 64 k EEPROM (8-kword x 8-bit) Ready/Busy function, RES function (HN58V66A)

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HN58V65A Datasheet, PDF (21/27 Pages) Hitachi Semiconductor – 64 k EEPROM (8-kword x 8-bit) Ready/Busy function, RES function (HN58V66A)

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HN58V65A Series, HN58V66A Series

2. Data protection at VCC on/off

When VCC is turned on or off, noise on the control pins generated by external circuits (CPU, etc) may

act as a trigger and turn the EEPROM to program mode by mistake. To prevent this unintentional

programming, the EEPROM must be kept in an unprogrammable state while the CPU is in an unstable

state.

Note: The EEPROM shoud be kept in unprogrammable state during VCC on/off by using CPU RESET

signal.

VCC

CPU

RESET

* Unprogrammable

(1) Protection by CE, OE, WE

To realize the unprogrammable state, the input level of control pins must be held as shown in the table

below.

VCC

VSS

VCC

Ã: Donât care.

VCC: Pull-up to VCC level.

VSS: Pull-down to VSS level.

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