ST52T400 datasheet(36/94 Pages) STMICROELECTRONICS

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ST52T400/T440/E440/T441

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3.1.5 Stand by Mode. EPROM has a standby

mode which reduces the active current from 10mA

(Programming mode) to less than 100

µA. Mem-

ory is placed in standby mode by setting PHASE

signal at high level or when the EPROM Control

3.1.6 ID code. A software identification code,

called ID code may be written to distinguish which

software version is stored in the memory.

64 Bytes are dedicated to store this code by using

the address values from 0 to 63.

The ID Code may be read or verified even if the

Memory Lock Status is “0".

The signals timing is the same as that of a normal

operation.

3.2 Eprom Erasure

Thanks to the transparent window available in the

CDIP28W package, its memory contents may be

erased by exposure to UV light.

Erasure begins when the device is exposed to

light with a wavelength shorter than 4000Å. It

should be noted that sunlight, as well as some

types of artificial light, includes wavelengths in the

3000-4000Å range which, on prolonged exposure,

can cause erasure of memory contents. It is thus

recommended that EPROM devices be fitted with

an opaque label over the window area in order to

prevent unintentional erasure.

The recommended erasure procedure for EPROM

devices consists of exposure to short wave UV

light having a wavelength of 2537Å. The minimum

recommended integrated dose (intensity x expo-

sure time) for complete erasure is 15Wsec/cm2.

This is equivalent to an erasure time of 5-10 min-

utes using a UV source having an intensity of

12mW/cm2 at a distance of 25mm (1 inch) from

the device window.

ST52T400 数据表(PDF) 36 Page - STMicroelectronics

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