SCI bus 4Kbit Serial CMOS EEPROM

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The AK6440B is a 4096bit, serial, read/write, non­volatile memory device fabricated using an advanced CMOS EEPROM technology.

The AK6440B has 4096bits of memory organized into 256 registers of 16 bits each.

The AK6440B can operate full function under wide operating voltage range from 1.8V to 5.5V. The charge up circuit is integrated for high voltage generation that is used for write operation.

The AK6440B can connect to the serial communication port of popular one chip microcomputer directly (3 line negative clock synchronous

interface). At write operation, AK6440B takes in the write data from data input pin (DI) to a register synchronously with rising edge of

input pulse of serial clock pin (SKB). And at read operation, AK6440B takes out the read data from a register to data output pin (DO)

synchronously with falling edge of SKB.

The AK6440B has 4 instructions such as READ, WRITE, WREN (write enable) and WRDS (write disable). Each instruction is organized by

op­code block (8bits), address block (8bits) and data (8bits×2). When input level of SKB pin is high level and input level of chip select (CSB) pin

is changed from high level to low level, AK6440B can receive the instructions.

Special features of the AK6440B include : automatic write time­-out with auto-­ERASE, Ready/BusyB status signal output and ultra-­low standby

power mode when deselected (CSB=high).

Key Features

□ Wide VCC (1.8V to 5.5V) operation

□ 4096 bits: 256×16 organization


­             - 0.8μA Max (Standby mode)


­             - Endurance : 100K cycles

­             - Data Retention : 10 years


­             - High speed operation ( fMAX=1MHz: VCC=2.5V )

             -­ Automatic write cycle time­-out with auto-­ERASE

­             - Automatic address increment (READ)

­             - Software and Hardware controlled write protection

□ 8pin SON

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Block Diagram

Block Diagram

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