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參數(shù)資料
| 型號： | DS87C550-FNL |
| 英文描述： | EPROM High-Speed Micro with A/D and PWM |
| 中文描述： | 存儲器高速微與A / D及PWM |
| 文件頁數(shù)： | 32/50頁 |
| 文件大?。?/td> | 763K |
| 代理商： | DS87C550-FNL |
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DS87C550
32 of 50
SECURITY OPTIONS
The DS87C550 employs a standard three-level lock that restricts viewing of the EPROM contents. A 64-
byte Encryption Array allows the authorized user to verify memory by presenting the data in encrypted
form.
Lock Bits
The security lock consists of 3 lock bits. These bits select a total of four levels. Higher levels provide
increasing security but also limit application flexibility. Table 11 shows the security settings. Note that
the programmer cannot directly read the state of the security lock.
Encryption Array
The Encryption Array allows an authorized user to verify EPROM without allowing the true memory to
be dumped. During a verify operation, each byte is Exclusive NORed (XNOR) with a byte in the
Encryption Array. This results in a true representation of the EPROM while the Encryption is
unprogrammed (FFh). Once the Encryption Array is programmed in a non- FFh state, the verify value will
be encrypted.
For encryption to be effective, the Encryption Array must be unknown to the party that is trying to verify
memory. The entire EPROM also should be a non- FFh state or the Encryption Array can be discovered.
The Encryption Array is programmed as shown in Table 10. Note that the programmer cannot read the
array. Also note that the verify operation always uses the Encryption Array. The array has no impact
while FFh. Simply programming the array to a non- FFh state will cause the encryption to function.
EPROM ERASURE CHARACTERISTICS
Erasure of the information stored in the DS87C550’s EPROM occurs when the isolated gate structure of
the EPROM stage element is exposed to certain wavelengths of light. While the gate structure is to some
degree sensitive to a wide range of wavelengths, it is mostly wavelengths shorter than approximately
4,000 angstroms that are most effective in erasing the EPROM. Since fluorescent lighting and sunlight
have wavelengths in this range, they can cause erasure if the device is exposed to them over an extended
period of time (weeks for sunlight, years in room-level fluorescent light). For this reason (and others
mentioned previously), it is recommended that an opaque covering be placed over the window of the -K
(windowed PLCC) package type.
For complete EPROM erasure, exposure to ultraviolet light at approximately 2537 angstroms to a dose of
15W-sec/cm
2
at minimum is recommended. In practice, exposing the EPROM to an ultraviolet lamp of
12,000uW/cm
2
rating for 20 to 39 minutes at a distance of approximately 1 inch will normally be
sufficient.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS87C550-KCL | EPROM High-Speed Micro with A/D and PWM |
| DS87C550-QNL | EPROM High-Speed Micro with A/D and PWM |
| DS8820J | Line Receiver |
| DS8859AJ | LED Display Driver |
| DS8859AN | LED Display Driver |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS87C550-KCL | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:EPROM High-Speed Micro with A/D and PWM |
| DS87C550-QCL | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:EPROM High-Speed Micro with A/D and PWM |
| DS87C550-QCL+ | 功能描述:IC MCU EPROM ADC/PWM HS 68-PLCC RoHS:是 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:87C 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:260 系列:73S12xx 核心處理器:80515 芯體尺寸:8-位 速度:24MHz 連通性:I²C，智能卡，UART/USART，USB 外圍設(shè)備:LED，POR，WDT 輸入/輸出數(shù):9 程序存儲器容量:64KB（64K x 8） 程序存儲器類型:閃存 EEPROM 大小:- RAM 容量:2K x 8 電壓 - 電源 (Vcc/Vdd):2.7 V ~ 5.5 V 數(shù)據(jù)轉(zhuǎn)換器:- 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 85°C 封裝/外殼:68-VFQFN 裸露焊盤 包裝:管件 |
| DS87C550-QCW | 制造商:Maxim Integrated Products 功能描述:DS87C550 WAIVERED FOR LS & MARKING - Rail/Tube |
| DS87C550-QNL | 功能描述:IC MCU EPROM ADC/PWM HS 68-PLCC RoHS:否 類別:集成電路 (IC) >> 嵌入式 - 微控制器， 系列:87C 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:260 系列:73S12xx 核心處理器:80515 芯體尺寸:8-位 速度:24MHz 連通性:I²C，智能卡，UART/USART，USB 外圍設(shè)備:LED，POR，WDT 輸入/輸出數(shù):9 程序存儲器容量:64KB（64K x 8） 程序存儲器類型:閃存 EEPROM 大小:- RAM 容量:2K x 8 電壓 - 電源 (Vcc/Vdd):2.7 V ~ 5.5 V 數(shù)據(jù)轉(zhuǎn)換器:- 振蕩器型:內(nèi)部 工作溫度:-40°C ~ 85°C 封裝/外殼:68-VFQFN 裸露焊盤 包裝:管件 |
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