HN58C65 Series
2. Data Protection at VCC On/Off
When V CC 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.
VCC
CPU
RESET
*Unprogrammable
* Unprogrammable
*The EEPROM should be kept in unprogrammable
state during VCC on/off by using CPU RESET signal.
In addition, when VCC is turned on or off, the input level of on control pins must be held as shown in the
table below.
CE
VCC
X
X
OE
X
VSS
X
WE
X
X
VCC
X: Don’t care.
VCC: Pull-up to VCC level
VSS: Pull-down to VSS level.
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