Features

– Single Cycle Reprogram (Erase and Program)

– 1024 Pages (264 Bytes/Page) Main Memory

while Reprogramming of Nonvolatile Memory

– Ideal for Code Shadowing Applications

– 4 mA Active Read Current Typical

– 2 µA CMOS Standby Current Typical

1.

Description

The AT45DB021B is a 2.7-volt only, serial interface Flash memory ideally suited for

a wide variety of digital voice-, image-, program code- and data-storage applications.

Its 2,162,688 bits of memory are organized as 1024 pages of 264 bytes each. In addi-

tion to the main memory, the AT45DB021B also contains two SRAM data buffers

of 264 bytes each. The buffers allow receiving of data while a page in the main mem-

ory is being reprogrammed, as well as reading or writing a continuous data stream.

EEPROM emulation (bit or byte alterability) is easily handled with a self-

contained three step Read-Modify-Write operation. Unlike conventional Flash

memories that are accessed randomly with multiple address lines and a parallel inter-

face, the DataFlash uses a SPI serial interface to sequentially access its data.

DataFlash supports SPI mode 0 and mode 3. The simple serial interface facilitates

hardware layout, increases system reliability, minimizes switching noise, and reduces

package size and active pin count. The device is optimized for use in many commer-

cial and industrial applications where high density, low pin count, low voltage, and low

power are essential. The device operates at clock frequencies up to 20 MHz with a

typical active read current consumption of 4 mA.

To allow for simple in-system reprogrammability, the AT45DB021B does not require

high input voltages for programming. The device operates from a single power supply,

2.7V to 3.6V, for both the program and read operations. The AT45DB021B 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.

When the device is shipped from Atmel, the most significant page of the memory

array may not be erased. In other words, the contents of the last page may not be

filled with FFH.

2-megabit

2.7-volt Only

AT45DB021B

1937J–DFLSH–9/05