Memoria eeprom

Páginas: 10 (2472 palabras) Publicado: 13 de noviembre de 2011
• Fast Read Access Time - 150 ns • Fast Byte Write - 200 µs or 1 ms • Self-Timed Byte Write Cycle
– Internal Address and Data Latches – Internal Control Timer – Automatic Clear Before Write Direct Microprocessor Control – DATA POLLING Low Power – 30 mA Active Current – 100 µA CMOS Standby Current High Reliability – Endurance: 104 or 105 Cycles – Data Retention: 10 Years 5V ± 10% SupplyCMOS & TTL Compatible Inputs and Outputs JEDEC Approved Byte Wide Pinout Commercial and Industrial Temperature Ranges

• • • • • • •

16K (2K x 8) Parallel EEPROMs AT28C16

The AT28C16 is a low-power, high-performance Electrically Erasable and Programmable Read Only Memory with easy to use features. The AT28C16 is a 16K memory organized as 2,048 words by 8 bits. The device ismanufactured with Atmel’s reliable (continued) nonvolatile CMOS technology.

Pin Configurations
Pin Name A0 - A10 CE OE WE I/O0 - I/O7 NC DC Function Addresses Chip Enable Output Enable Write Enable Data Inputs/Outputs No Connect Don’t Connect PLCC Top View
A7 NC NC DC VCC WE NC A7 A6 A5 A4 A3 A2 A1 A0 I/O0 I/O1 I/O2 GND

PDIP SOIC , Top View
1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 1817 16 15 14 13 VCC A8 A9 WE OE A10 CE I/O7 I/O6 I/O5 I/O4 I/O3

I/O1 I/O2 GND DC I/O3 I/O4 I/O5

14 15 16 17 18 19 20

A6 A5 A4 A3 A2 A1 A0 NC I/O0

5 6 7 8 9 10 11 12 13

4 3 2 1 32 31 30

29 28 27 26 25 24 23 22 21

A8 A9 NC NC OE A10 CE I/O7 I/O6

Note: PLCC package pins 1 and 17 are DON’T CONNECT.

Rev. 0540B–10/98


The AT28C16 is accessed like a static RAM for theread or write cycles without the need of external components. During a byte write, the address and data are latched internally, freeing the microprocessor address and data bus for other operations. Following the initiation of a write cycle, the device will go to a busy state and automatically clear and write the latched data using an internal control timer. The end of a write cycle can be determinedby DATA POLLING of I/O7. Once the end of a write cycle has been detected, a new access for a read or a write can begin.

The CMOS technology offers fast access times of 150 ns at low power dissipation. When the chip is deselected the standby current is less than 100 µA. Atmel’s 28C16 has additional features to ensure high quality and manufacturability. The device utilizes error correctioninternally for extended endurance and for improved data retention characteristics. An extra 32 bytes of EEPROM are available for device identification or tracking.

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) withRespect to Ground ...................................-0.6V to +6.25V All Output Voltages with Respect to Ground .............................-0.6V to VCC + 0.6V Voltage on OE and A9 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 andfunctional 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



Device Operation
READ: The AT28C16 is accessed like a Static RAM. When CE and OE are low and WE is high, the datastored at the memory location determined by the address pins is asserted on the outputs. The outputs are put in a high impedance state whenever CE or OE is high. This dual line control gives designers increased flexibility in preventing bus contention. BYTE WRITE: Writing data into the AT28C16 is similar to writing into a Static RAM. A low pulse on the WE or CE input with OE high and CE or WE low...
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