User Manual

AT28C040

The AT28C040 is accessed like a static RAM for the read

or write cycle without the need for external components.

The devi ce c ontai ns a 256-by te pa ge regi ster to a llow writ-

ing of u p to 256 b yt es simul tan eou sl y. Dur in g a wr it e cyc le ,

the address and 1 to 256 bytes of data are internally

latched, freeing the address and data bus for other opera-

tions. Following the initiation of a write cycle, the device will

automatically write the latched data using an internal con-

trol timer. The end of a write cycle can be detected by

DATA

POLLING of I/O7. Once th e end of a write cy cle has

been detected, a new access for a read or write can begin.

Atmel's AT28C040 has add itional features to ensure high

quality and manufacturability. The device utilizes internal

error correction for extended endurance and improved data

retention characteristics. An optional software data protec-

tion mechanism is available to guard against inadvertent

writes. The device also includes an extra 256 bytes of

EEPROM for device identification or tracking.

Bloc k Diagram

Absolute Maximum Ratings*

Temperature Under Bias................................ -55

C to +125

*NOTICE: Stresses beyond those listed under “Absolute

Maximum Ratings” may cause per manent dam-

age to the device. This is a stres s ra ting onl y and

funct ion al ope ration of th e d evice at these o r any

other conditions beyond those indicated in the

operational sections of this specification is not

implied. Exposure to absolute maximum rating

conditi ons f or e xtended p eriods ma y af fect dev ice

reliability .

Storage Temperature ..................................... -65

C to +150

All Input Voltages

(including NC pins)

with Respect to Ground ...................................-0.6V to +6.25V

All Output Voltages

with Respect to Ground .............................-0.6V to V

+ 0.6V

Voltage on OE

and A9

with Respect to Ground ...................................-0.6V to +13.5V