Rainbow Electronics AT29C257 - Manual

AT29C257
Features
•
Fast Read Access Time - 70 ns
•
5-Volt-Only Reprogramming
•
Page Program Operation
Single Cycle Reprogram (Erase and Program)
Internal Address and Data Latches for 64-Bytes
•
Internal Program Control and Timer
•
Hardware and Software Data Protection
•
Fast Program Cycle Times
Page (64-Byte) Program Time - 10 ms
Chip Erase Time - 10 ms
•
DATA Polling for End of Program Detection
•
Low Power Dissipation
50 mA Active Current
300
µ
A CMOS Standby Current
•
Typical Endurance > 10,000 Cycles
•
Single 5V
±
10% Supply
•
CMOS and TTL Compatible Inputs and Outputs
•
Pin-Compatible with AT29C010A and AT29C512 for Easy System Upgrades
Description
The AT29C257 is a 5-volt-only in-system Flash programmable and erasable read only
memory (PEROM). Its 256K of memory is organized as 32,768 words by 8 bits. Manu-
factured with Atmel’s advanced nonvolatile CMOS technology, the device offers ac-
cess times to 70 ns with power dissipation of just 275 mW. When the device is dese-
lected, the CMOS standby current is less than 300
µ
A. The device endurance is such
that any sector can typically be written to in excess of 10,000 times.
To allow for simple in-system reprogrammability, the AT29C257 does not require high
input voltages for programming. Five-volt-only commands determine the operation of
the device. Reading data out of the device is similar to reading from a static RAM.
Reprogramming the AT29C257 is performed on a page basis; 64-bytes of data are
loaded into the device and then simultaneously programmed. The contents of the
entire device may be erased by using a 6-byte software code (although erasure before
programming is not needed).
During a reprogram cycle, the address locations and 64-bytes of data are internally
latched, freeing the address and data bus for other operations. Following the initiation
of a program cycle, the device will automatically erase the page and then program the
latched data using an internal control timer. The end of a program cycle can be de-
tected by DATA polling of I/O7. Once the end of a program cycle has been detected
a new access for a read, program or chip erase can begin.
Pin Name Function
A0 - A14 Addresses
CE Chip Enable
OE Output Enable
WE Write Enable
I/O0 - I/O7 Data Inputs/Outputs
NC No Connect
DC Don’t Connect
Pin Configurations
256K (32K x 8)
5-volt Only
CMOS Flash
Memory
PLCC Top View
0012K
AT29C257
4-105