NEC user manual Erasure μPD75P308K only

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μPD75P308

3.4 ERASURE (μPD75P308K ONLY)

The contents of the data programmed to the μPD75P308 can be erased by exposing the window of the program memory to ultraviolet rays.

The wavelength of the ultraviolet rays used to erase the contents is about 250 nm, and the quantity of the ultraviolet rays necessary for complete erasure is 15 W.s/cm2 (= ultraviolet ray intensity x erasure time).

When a commercially available ultraviolet ray lamp (wavelength: 254 nm, intensity: 12 mW/cm2) is used, about 15 to 20 minutes is required.

Note 1: The contents of the program memory may be erased when the μPD75P308 is exposed for a long time to direct sunlight or the light of fluorescent lamps. To protect the contents from being erased, mask the window of the program memory with the light-opaque film supplied as an accessory with the UV EPROM products.

2:To erase the memory contents, the distance between the ultraviolet ray lamp and the μPD75P308 should be 2.5 cm or less.

Remarks: The time required for erasure changes depending on the degradation of the ultraviolet ray

lamp and the surface condition (dirt) of the window of the program memory.

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Contents Ordering Information FeaturesDescription Quality GradePIN Configuration ΜPD75P308Block Diagram Contents Port Pins PIN FunctionsNON Port Pins Input buffer of Cmos standard Schmitt trigger input with hysteresis characteristicsPIN INPUT/OUTPUT Circuits IN/OUT SEG COMType F-B Connect capacitor between VDD and P00/INT4, Reset pin Type M-CDifferences Between μPD75P308 and μPD75308 EpromWriting and Verifying Prom Program Memory Program memory address 0 clear mode+12.5 Write mode Verify mode Program inhibit mode Or H Operation Modes for WRITING/VERIFYING Program MemoryProgram Memory Write Procedure VDD+1Program Memory Read Procedure Erasure μPD75P308K only Electrical Specifications Absolute Maximum Ratings Ta = 25CRecommended Oscillation Circuit Constants Main System Clock Oscillator Circuit CharacteristicsTa = -10 to +70C, VDD = 5 to ±5 Main System Clock Ceramic Oscillator Ta = -10 to +70CCapacitance Ta = 25C, VDD = 0 DC Characteristics Ta = -10 to +70C, VDD = 5V ±5% Operation Other Than Serial Transfer AC Characteristics Ta = -10 to + 70C, VDD = 5V ±5%Interrupt mode register IM0 Serial Transfer Operation SBI Mode SCK internal clock output master SBI Mode SCK external clock output masterTI0 Timing AC Timing Test Point excluding X1 and XT1 inputsClock Timing Serial Transfer Timing THREE-LINE Serial I/O Mode TWO-LINE Serial I/O ModeReset Input Timing Serial Transfer Timing BUS Release Signal TransferCommand Signal Transfer Interrupt Input TimingBTM3 BTM2 BTM1 BTM0 Data Retention Timing releasing Stop mode by ResetTa = -10 to +70C Other than X1 or MD0 MD1 Program Memory Write TimingProgram Memory Read Timing Package Drawings PIN Plastic QFP 14×20PIN Ceramic Wqfn Millimeters InchesVPS Recommended Soldering ConditionsΜPD75P308GF-3B9 80-pin plastic QFP 14 x 20 mm Appendix A. Development Tools Prom writing toolsAppendix B. Related Documents Status Before Initialization ALL MOS Devices Processing of Unused Pins Cmos Devices onlyStatic Electricity ALL MOS Devices Fix the input level of Cmos devicesMemo