AT45D021A datasheet(2/28 Pages) ATMEL

2 / 28 page

AT45D021A

memories that are accessed randomly with multiple

address lines and a parallel interface, the DataFlash uses a

serial interface to sequentially access its data. The simple

serial interface facilitates hardware layout, increases sys-

tem reliability, minimizes switching noise, and reduces

package size and active pin count. The device is optimized

for use in many commercial and industrial applications

where high density, low pin count, low voltage, and low

power are essential. Typical applications for the DataFlash

are digital voice storage, image storage, and data storage.

The device operates at clock frequencies up to 15 MHz

with a typical active read current consumption of 15 mA.

To allow for simple in-system reprogrammability, the

AT45D021A does not require high input voltages for pro-

gramming. The device operates from a single power

supply, 4.5V to 5.5V, for both the program and read opera-

tions. The AT45D021A is enabled through the chip select

pin (CS) and accessed via a three-wire interface consisting

of the Serial Input (SI), Serial Output (SO), and the Serial

Clock (SCK).

All programming cycles are self-timed, and no separate

erase cycle is required before programming.

Block Diagram

Memory Array

To provide optimal flexibility, the memory array of the

AT45D021A is divided into three levels of granularity com-

prised of sectors, blocks and pages. The Memory Architec-

ture Diagram illustrates the breakdown of each level and

details the number of pages per sector and block. All pro-

gram operations to the DataFlash occur on a page-by-page

basis; however, the optional erase operations can be per-

formed at the block or page level.

FLASH MEMORY ARRAY

PAGE (264 BYTES)

BUFFER 2 (264 BYTES)

BUFFER 1 (264 BYTES)

I/O INTERFACE

SCK

RESET

VCC

GND

RDY/BUSY

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