AT27C400

The AT27C400 is a low-power, high-performance 4,194,304-bit one-time programmable read only memory (OTP EPROM) organized as either 256K by 16 or 512K by 8 bits. It requires a single 5V power supply in normal read mode operation. Any word can be accessed in less than 70 ns, eliminating the need for speed-reducing WAIT states. The by-16 organization makes this part ideal for high-performance 16- and 32- bit microprocessor systems.

The AT27C400 can be organized as either word-wide or byte-wide. The organization is selected via the BYTE/VPP pin. When BYTE/VPP is asserted high (V_IH), the word-wide organization is selected and the O15/A-1 pin is used for O15 data output. When BYTE/VPP is asserted low (V_IL), the byte-wide organization is selected and the O15/A-1 pin is used for the address pin A-1. When the AT27C400 is logically regarded as x16 (word-wide), but read in the bytewide mode, then with A-1 = V_IL the lower 8 bits of the 16-bit word are selected and with A-1 = V_IH the upper 8 bits of the 16-bit word are selected.

In read mode, the AT27C400 typically consumes 15 mA. Standby mode supply current is typically less than 10 A. The AT27C400 is available in industry standard JEDEC-approved one-time programmable (OTP) PDIP, SOIC (SOP), and TSOP packages. The device features two-line control (CE, OE) to eliminate bus contention in high-speed systems.

With high density 256K word or 512K byte storage capability, the AT27C400 allows firmware to be stored reliably and to be accessed by the system without the delays of mass storage media.

Atmel's AT27C400 has additional features that ensure high quality and efficient production use. The Rapid™ Programming Algorithm reduces the time required to program the part and guarantees reliable programming. Programming time is typically only 50 ms/word. The Integrated Product Identification Code electronically identifies the device and manufacturer. This feature is used by industry standard programming equipment to select the proper programming algorithms and voltages.