Features

– Internal Address and Data Latches for 64 Bytes

– Internal Control Timer

– Page Write Cycle Time: 3 ms or 10 ms Maximum

– 1 to 64-byte Page Write Operation

– 50 mA Active Current

– 200 µA CMOS Standby Current

– Data Retention: 10 Years

1.

Description

The AT28C256 is a high-performance electrically erasable and programmable read-

only memory. Its 256K of memory is organized as 32,768 words by 8 bits. Manufac-

tured with Atmel’s advanced nonvolatile CMOS technology, the device offers access

times to 150 ns with power dissipation of just 440 mW. When the device is deselected,

the CMOS standby current is less than 200 µA.

The AT28C256 is accessed like a Static RAM for the read or write cycle without the

need for external components. The device contains a 64-byte page register to allow

writing of up to 64 bytes simultaneously. During a write cycle, the addresses and 1 to

64 bytes of data are internally latched, freeing the address and data bus for other

operations. Following the initiation of a write cycle, the device will automatically write

the latched data using an internal control timer. The end of a write cycle can be

detected by DATA Polling of I/O7. Once the end of a write cycle has been detected a

new access for a read or write can begin.

Atmel’s AT28C256 has additional features to ensure high quality and manufacturabil-

ity. The device utilizes internal error correction for extended endurance and improved

data retention characteristics. An optional software data protection mechanism is

available to guard against inadvertent writes. The device also includes an extra

64 bytes of EEPROM for device identification or tracking.

256K (32K x 8)

Paged Parallel

EEPROM

AT28C256

0006M–PEEPR–12/09