Low Voltage 4 Megabit (512k x 8-bit) EEPROM MCM
79LV0408
During readout or standby, noise on the control pins may act as a trigger and turn the EEPROM to programming mode by mis-
take. To prevent this phenomenon, the EEPROM has a noise cancellation function that cuts noise if its width is 20 ns or less in
programming mode. Be careful not to allow noise of a width of more than 20ns on the control pins.
2. Data Protection at VCC on/off
When V is turned on or off, noise on the control pins generated by external circuits, such as CPUs, may turn the EEPROM to
CC
programming mode by mistake. To prevent this unintentional programming, the EEPROM must be kept in unprogrammable
state during VCC on/off by using a CPU reset signal to RES pin.
RES should be kept at V level when VCC is turned on or off. The EEPROM breaks off programming operation when RES
SS
becomes low, programming operation doesn’t finish correctly in case that RES falls low during programming operation. RES
should be kept high for 10 ms after the last data input.
10mS min
3. Software Data Protection
The software data protection function is to prevent unintentional programming caused by noise generated by external circuits.
In software data protection mode, 3 bytes of data must be input before write data as follows. These bytes can switch the non-
protection mode to the protection mode.
01.11.05 Rev 7
All data sheets are subject to change without notice 14
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