Summary description
The M27C256B is a 256 Kbit EPROM offered in the two ranges UV (ultra violet erase) and OTP (one time programmable). It is ideally suited for microprocessor systems and is organized as 32,768 by 8 bits.
The FDIP28W (window ceramic frit-seal package) has a transparent lid which allows the user to expose the chip to ultraviolet light to erase the bit pattern. A new pattern can then be written to the device by following the programming procedure.
For applications where the content is programmed only one time and erasure is not required, the M27C256B is offered in PDIP28 and PLCC32 packages.
In order to meet environmental requirements, ST offers the M27C256B in ECOPACK® packages.

FEATURE summary
■ 5V ± 10% supply voltage in Read operation
■ Access time: 45ns
■ Low power consumption:
   – Active Current 30mA at 5MHz
   – Standby Current 100µA
■ Programming voltage: 12.75V ± 0.25V
■ Programming time: 100µs/Word
■ Electronic signature
   – Manufacturer Code: 20h
   – Device Code: 8Dh
■ ECOPACK® packages available