參數(shù)資料
型號(hào): MB90V230
廠商: Fujitsu Limited
英文描述: 16-bit Proprietary Microcontroller
中文描述: 16位微控制器專有
文件頁(yè)數(shù): 16/83頁(yè)
文件大小: 1513K
代理商: MB90V230
MB90230 Series
16
8. Program Mode
When shipped from Fujitsu, and after each erasure, all bits (96K
×
8 bits) in the MB90W234 and MB90P234 are
in the “1” state. Data is introduced by selectively programming “0’s” into the desired bit locations. Bits cannot
be set to 1 electrically.
9. Erasure Procedure
Data written in the MB90W234 is erased (from 0 to 1) by exposing the chip to ultraviolet rays with a wavelength
of 2,537 through the translucent cover.
Recommended irradiation dosage for exposure is 10 Wsec/cm
2
. This amount is reached in 15 to 20 minutes
with a commercial ultraviolet lamp positioned 2 to 3 cm above the package (when the package surface
illuminance is 1200
μ
W/cm
2
).
If the ultraviolet lamp has a filter, remove the filter before exposure. Attaching a mirrored plate to the lamp
increases the illuminance by a factor of 1.4 to 1.8, thus shortening the required erasure time. If the translucent
part of the package is stained with oil or adhesive, transmission of ultraviolet rays is degraded, resulting in a
longer erasure time. In that case, clean the translucent part using alcohol (or other solvent not affecting the
package).
The above recommended dosage is a value which takes the guard band into consideration and is a multiple of
the time in which all bits can be evaluated to have been erased. Observe the recommended dosage for erasure;
the purpose of the guard band is to ensure erasure in all temperature and supply voltage ranges. In addition,
check the lifespan of the lamp and control the illuminance appropriately.
Data in the MB90W234 is erased by exposure to light with a wavelength of 4000 or less.
Data in the device is also erased even by exposure to fluorescent lamp light or sunlight although the exposure
results in a much lower erasure rate than exposure to 2537 ultraviolet rays. Note that exposure to such lights
for an extended period will therefore affect system reliability. If the chip is used where it is exposed to any light
with a wavelength of 4000 or less, cover the translucent part, for example, with a protective seal to prevent
the chip from being exposed to the light.
Exposure to light with a wavelength of 4,000 to 5,000 or more will not erase data in the device. If the light
applied to the chip has a very high illuminance, however, the device may cause malfunction in the circuit for
reasons of general semiconductor characteristics. Although the circuit will recover normal operation when
exposure is stopped, the device requires proper countermeasures for use in a place exposed continuously to
such light even though the wavelength is 4,000 or more.
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