2

AT49F040A

3359B–FLASH–10/04

When the device is deselected, the CMOS standby current is less than 70 µA. To allow for

simple in-system reprogrammability, the AT49F040A does not require high input voltages for

programming. Five-volt-only commands determine the read and programming operation of the

device. Reading data out of the device is similar to reading from an EPROM; it has standard

CE, OE, and WE inputs to avoid bus contention. Reprogramming the AT49F040A is per-

formed by erasing a block of data and then programming on a byte-by-byte basis. The byte

programming time is a fast 20 µs. The end of a program cycle can be optionally detected by

the DATA polling feature. Once the end of a byte program cycle has been detected, a new

access for a read or program can begin. The typical number of program and erase cycles is in

excess of 10,000 cycles.

The device is erased by executing the erase command sequence; the device internally con-

trols the erase operations. There are two 8K byte parameter block sections, eight main

memory blocks, and one boot block.

The device has the capability to protect the data in the boot block; this feature is enabled by a

command sequence. The 16K-byte boot block section includes a reprogramming lock out fea-

ture to provide data integrity. The boot sector is designed to contain user secure code, and

when the feature is enabled, the boot sector is permanently protected from being

reprogrammed.

Block Diagram

CONTROL

LOGIC

Y DECODER

PARAMETER

BLOCK 1

(8K BYTES)

BOOT BLOCK

(16K BYTES)

OE

WE

CE

RESET

ADDRESS

INPUTS

VCC

GND

AT49F040A

DATA INPUTS/OUTPUTS

I/O7 - I/O0

8

X DECODER

PARAMETER

BLOCK 2

(8K BYTES)

MAIN MEMORY

BLOCK 1

(32K BYTES)

MAIN MEMORY

BLOCK 2

(64K BYTES)

MAIN MEMORY

BLOCK 3

(64K BYTES)

MAIN MEMORY

BLOCK 4

(64K BYTES)

MAIN MEMORY

BLOCK 8

(64K BYTES)

MAIN MEMORY

BLOCK 7

(64K BYTES)

MAIN MEMORY

BLOCK 6

(64K BYTES)

MAIN MEMORY

BLOCK 5

(64K BYTES)

PROGRAM

DATA LATCHES

Y-GATING

INPUT/OUTPUT

BUFFERS

1FFFF

10000

0FFFF

08000

3FFFF

30000

2FFFF

20000

07FFF

06000

05FFF

04000

03FFF

00000

7FFFF

70000

6FFFF

60000

5FFFF

50000

4FFFF

40000