ST72T331 STMICROELECTRONICS [STMicroelectronics], ST72T331 Datasheet - Page 102

• Manufacturer Part Number: ST72T331
• Description: 8-BIT MCU WITH 8 TO 16K OTP/EPROM, 256 EEPROM, 384 TO 512 BYTES RAM, ADC, WDG, SCI, SPI AND 2 TIMERS
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST72E331 ST72T331
8 GENERAL INFORMATION
8.1 EPROM ERASURE
EPROM version devices are erased by exposure
to high intensity UV light admitted through the
transparent window. This exposure discharges the
floating gate to its initial state through induced
photo current.
It is recommended that the EPROM devices be
kept out of direct sunlight, since the UV content of
sunlight can be sufficient to cause functional fail-
ure. Extended exposure to room level fluorescent
lighting may also cause erasure.
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An opaque coating (paint, tape, label, etc...)
should be placed over the package window if the
product is to be operated under these lighting con-
ditions. Covering the window also reduces I
power-saving modes due to photo-diode leakage
currents.
An Ultraviolet source of wave length 2537 Å yield-
ing a total integrated dosage of 15 Watt-sec/cm
required to erase the device. It will be erased in 15
to 20 minutes if such a UV lamp with a 12mW/cm
power rating is placed 1 inch from the device win-
dow without any interposed filters.
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