Original Programming IC Chips 256K 32K X 8 5 Volt Only Cmos Flash
Memory AT29C256
256K (32K x 8) 5-volt Only Flash Memory AT29C256
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 µA CMOS Standby Current
• Typical Endurance > 10,000 Cycles
• Single 5V ± 10% Supply
• CMOS and TTL Compatible Inputs and Outputs
• Commercial and Industrial Temperature Ranges
Description
The AT29C256 is a five-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. Manufactured with Atmel’s advanced
nonvolatile CMOS technology, the device offers access times to 70
ns with power dissipation of just 275 mW. When the device is
deselected, the CMOS standby current is less than 300 µA. The
device endurance is such that any sector can typically be written
to in excess of 10,000 times.
Pin Configurations
| 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 |
PLCC and LCC Top View
Note: PLCC package pins 1 and 17 are DON’T CONNECT.
TSOP Top View Type 1
To allow for simple in-system reprogrammability, the AT29C256 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 AT29C256 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 six-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 detected 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.
Block Diagram
Absolute Maximum Ratings*
Temperature Under Bias................................ -55°C to
+125°C
Storage Temperature..................................... -65°C to
+150°C
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 VCC +
0.6V
Voltage on OE
with Respect to Ground ...................................-0.6V to
+13.5V
*NOTICE: Stresses beyond those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at these or any
other conditions beyond those indicated in the operational sections
of this specification is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device
reliability.
