256K EEPROM (32K x 8-Bit) EEPROM
EEPROM A
PPLICATION
N
OTES
28C256T
This application note describes the programming procedures for the EEPROM modules and the details of various
techniques to preserve data protection.
Automatic Page Write
Page-mode write feature allows 1 to 64 bytes of data to be written into the EEPROM in a single write cycle, and allows
the undefined data within 64 bytes to be written corresponding to the undefined address (A0 to A5). Loading the first
byte of data, the data load window opens 30 µ s for the second byte. In the same manner each additional byte of data
can be loaded within 30 µ s. In case CE and WE are kept high for 100(s after data input, EEPROM enters erase and
write mode automatically and only the input data are written into the EEPROM.
WE CE Pin Operation
During a write cycle, addresses are latched by the falling edge of WE or CE, and data is latched by the rising edge of
WE or CE.
Data Polling
Data Polling function allows the status of the EEPROM to be determined. If EEPROM is set to read mode during a
write cycle, an inversion of the last byte of data to be loaded outputs from I/O 7 to indicate that the EEPROM is per-
forming a write operation.
Memory
Data Protection
To protect the data during operation and power on/off, the EEPROM has the internal functions described below.
1. Data Protection against Noise of Control Pins (CE, OE, WE) during Operation.
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 20ns or less in
programming mode. Be careful not to allow noise of a width of more than 20ns on the control pins.
02.18.02 Rev5
All data sheets are subject to change without notice
10
©2001 Maxwell Technologies
All rights reserved.
MAXWELL [ MAXWELL TECHNOLOGIES ]
