AT29C020-12PC Atmel, AT29C020-12PC Datasheet - Page 3

• Manufacturer Part Number: AT29C020-12PC
• Description: IC FLASH 2MBIT 120NS 32DIP
• Manufacturer: Atmel

Specifications of AT29C020-12PC

• Format - Memory: FLASH
• Memory Type: FLASH
• Memory Size: 2M (256K x 8)
• Speed: 120ns
• Interface: Parallel
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 32-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

3. Block Diagram
4. Device Operation
4.1
4.2
4.3
4.4
0291S–FLASH–11/08
Read
Byte Load
Program
Software Data Protection
The AT29C020 is accessed like an EPROM. When CE and OE are low and WE is high, the data
stored at the memory location determined by the address pins is asserted on the outputs. The
outputs are put in the high impedance state whenever CE or OE is high. This dual-line control
gives designers flexibility in preventing bus contention.
Byte loads are used to enter the 256 bytes of a sector to be programmed or the software codes
for data protection. A byte load is performed by applying a low pulse on the WE or CE input with
CE or WE low (respectively) and OE high. The address is latched on the falling edge of CE or
WE, whichever occurs last. The data is latched by the first rising edge of CE or WE.
The device is reprogrammed on a sector basis. If a byte of data within a sector is to be changed,
data for the entire sector must be loaded into the device. Any byte that is not loaded during the
programming of its sector will be indeterminate. Once the bytes of a sector are loaded into the
device, they are simultaneously programmed during the internal programming period. After the
first data byte has been loaded into the device, successive bytes are entered in the same man-
ner. Each new byte to be programmed must have its high-to-low transition on WE (or CE) within
150 µs of the low-to-high transition of WE (or CE) of the preceding byte. If a high-to-low transi-
tion is not detected within 150 µs of the last low-to-high transition, the load period will end and
the internal programming period will start. A8 to A17 specify the sector address. The sector
address must be valid during each high-to-low transition of WE (or CE). A0 to A7 specify the
byte address within the sector. The bytes may be loaded in any order; sequential loading is not
required. Once a programming operation has been initiated, and for the duration of t
operation will effectively be a polling operation.
A software controlled data protection feature is available on the AT29C020. Once the software
protection is enabled a software algorithm must be issued to the device before a program may
be performed. The software protection feature may be enabled or disabled by the user; when
AT29C020
WC
, a read
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