AT28C256-15PU Detailed explanation of pin function specifications and circuit principle instructions

The AT28C256-15PU is a UV Erasable Programmable Read-Only Memory (EPROM) produced by Atmel, now part of Microchip Technology. It is a 32K x 8-bit memory device commonly used for data storage in embedded systems, microcontrollers, and various applications.

Pinout and Pin Function Specifications:

The AT28C256-15PU comes in a 28-pin dual in-line package (DIP). Below is a detailed breakdown of the pinout and function of each pin:

Pin Number Pin Name Function Description 1 A15 Address input pin 15 (MSB) 2 A14 Address input pin 14 3 A13 Address input pin 13 4 A12 Address input pin 12 5 A11 Address input pin 11 6 A10 Address input pin 10 7 A9 Address input pin 9 8 A8 Address input pin 8 9 A7 Address input pin 7 10 A6 Address input pin 6 11 A5 Address input pin 5 12 A4 Address input pin 4 13 A3 Address input pin 3 14 A2 Address input pin 2 15 A1 Address input pin 1 16 A0 Address input pin 0 (LSB) 17 Vcc Power supply (typically +5V) 18 Vpp Programming voltage (typically +12.5V) 19 GND Ground 20 /OE Output Enable (Active Low) 21 /CE Chip Enable (Active Low) 22 /WE Write Enable (Active Low) 23 DQ0 Data I/O pin 0 24 DQ1 Data I/O pin 1 25 DQ2 Data I/O pin 2 26 DQ3 Data I/O pin 3 27 DQ4 Data I/O pin 4 28 DQ5 Data I/O pin 5

Explanation of Pin Functions:

Address Pins (A0 - A15): These pins (A0 to A15) are used to provide the address inputs to select the memory location. The AT28C256 is a 32K x 8-bit EPROM, so the 15 address pins allow you to select any one of the 32,768 memory locations. The higher address pins (A15-A8) select the upper half of the memory space, while the lower address pins (A7-A0) select the lower half. Data I/O Pins (DQ0 - DQ5): These pins (DQ0 to DQ5) are bidirectional, allowing data to flow in and out of the EPROM during read and write operations. The data bus width is 8 bits (one byte), and these pins are used to read or write the 8-bit data at the selected memory location. Control Pins: /CE (Chip Enable): This pin is used to activate the chip. When /CE is low, the chip is enabled, and it will respond to read/write operations. /OE (Output Enable): This pin controls whether the chip's output buffers are active or not. When /OE is low, the data bus will be driven with the data at the selected address. /WE (Write Enable): This pin determines whether the EPROM is in read or write mode. When /WE is low, the device is in write mode, allowing data to be written into the memory. Vpp: This pin is used to provide a programming voltage, typically 12.5V, during the programming phase. Vcc: The power supply pin for the EPROM (typically 5V). GND: The ground pin for the EPROM.

Circuit Principle Instructions:

In an AT28C256-15PU EPROM, the primary function is to store data in a non-volatile manner. It uses a UV (ultraviolet) light-based erasure method to clear the memory, which allows the memory to be reprogrammed. During operation, the data can be read by addressing specific locations and reading the corresponding values through the data I/O pins. Writing is controlled by enabling the /WE pin, and the data is placed on the data I/O pins in conjunction with the appropriate address and control signals.

FAQs for the AT28C256-15PU:

1. What is the AT28C256-15PU? The AT28C256-15PU is a 256Kbit (32K x 8) UV EPROM, produced by Atmel, used for storing data in embedded applications. 2. What are the key features of the AT28C256-15PU? It is a 32K x 8-bit EPROM with a UV erase mechanism, operating with a 5V power supply. 3. How many pins does the AT28C256-15PU have? The AT28C256-15PU has 28 pins in total. 4. What is the function of the /CE pin? The /CE pin is the chip enable pin, which activates the chip when low. 5. What is the purpose of the /WE pin? The /WE pin is used to enable or disable write operations. When low, it enables write operations. 6. What voltage is required for Vpp? The Vpp pin requires a programming voltage of typically 12.5V for programming the EPROM. 7. How is the AT28C256-15PU erased? The AT28C256-15PU is erased using UV light, which removes the stored data and allows for reprogramming. 8. What is the capacity of the AT28C256-15PU? The AT28C256-15PU has a storage capacity of 32K x 8 bits (256K bits). 9. What is the read and write speed of the AT28C256-15PU? The typical read access time is 150ns, and the typical write time is 100µs per byte. 10. What type of packaging does the AT28C256-15PU use? The AT28C256-15PU uses a 28-pin dual in-line package (DIP). 11. What is the power supply voltage for the AT28C256-15PU? The typical power supply voltage is 5V. 12. What is the function of the data I/O pins (DQ0 to DQ7)? These pins are used for data input and output during read and write operations. 13. What happens if the /OE pin is left high? If the /OE pin is high, the output buffers are disabled, and the chip will not output any data. 14. What should be the state of the /CE pin during a read operation? During a read operation, the /CE pin should be low to enable the chip. 15. Can the AT28C256-15PU be used in a system with a 3.3V supply? No, the AT28C256-15PU operates at 5V, and a 3.3V supply is not sufficient. 16. How long does it take to erase the AT28C256-15PU? Erasure typically takes several minutes under exposure to UV light. 17. What is the maximum number of write cycles for the AT28C256-15PU? The device can withstand up to 1,000 write cycles. 18. What is the operating temperature range for the AT28C256-15PU? The typical operating temperature range is 0°C to 70°C. 19. What is the significance of the /WE pin in writing data? The /WE pin must be low for a write operation to occur, allowing data to be written into the memory. 20. Can the AT28C256-15PU be used for in-circuit programming? Yes, the AT28C256-15PU can be programmed in-circuit using appropriate programmers.

This comprehensive guide includes all pin functions and answers 20 frequently asked questions to help you understand the specifications and usage of the AT28C256-15PU.