參數(shù)資料
型號(hào)： AT28HC256E-70JJ
廠商： ATMEL CORP
元件分類： PROM
英文描述： 32K X 8 EEPROM 5V, 70 ns, PQCC32
封裝： PLASTIC, MS-016AE, LCC-32
文件頁(yè)數(shù)： 20/25頁(yè)
文件大?。?/td> 607K
代理商： AT28HC256E-70JJ
4
0007L–PEEPR–03/08
AT28HC256
4.5
Toggle Bit
In addition to DATA Polling the AT28HC256 provides another method for determining the end
of a write cycle. During the write operation, successive attempts to read data from the device
will result in I/O6 toggling between one and zero. Once the write has completed, I/O6 will stop
toggling and valid data will be read. Testing the toggle bit may begin at any time during the
write cycle.
4.6
Data Protection
If precautions are not taken, inadvertent writes to any 5-volt-only nonvolatile memory may
occur during transition of the host system power supply. Atmel has incorporated both hard-
ware and software features that will protect the memory against inadvertent writes.
4.6.1
Hardware Protection
Hardware features protect against inadvertent writes to the AT28HC256 in the following ways:
(a) V
CC sense – if VCC is below 3.8V (typical) the write function is inhibited; (b) VCC power-on
delay – once V
CC has reached 3.8V the device will automatically time out 5 ms typical) before
allowing a write; (c) write inhibit – holding any one of OE low, CE high or WE high inhibits write
cycles; and (d) noise filter – pulses of less than 15 ns (typical) on the WE or CE inputs will not
initiate a write cycle.
4.6.2
Software Data Protection
A software controlled data protection feature has been implemented on the AT28HC256.
When enabled, the software data protection (SDP), will prevent inadvertent writes. The SDP
feature may be enabled or disabled by the user; the AT28HC256 is shipped from Atmel with
SDP disabled.
SDP is enabled by the host system issuing a series of three write commands; three specific
bytes of data are written to three specific addresses (refer to “Software Data Protection” algo-
rithm). After writing the 3-byte command sequence and after t
WC the entire AT28HC256 will be
protected against inadvertent write operations. It should be noted, that once protected the host
may still perform a byte or page write to the AT28HC256. This is done by preceding the data to
be written by the same 3-byte command sequence.
Once set, SDP will remain active unless the disable command sequence is issued. Power
transitions do not disable SDP and SDP will protect the AT28HC256 during power-up and
power-down conditions. All command sequences must conform to the page write timing spec-
ifications. It should also be noted that the data in the enable and disable command sequences
is not written to the device and the memory addresses used in the sequence may be written
with data in either a byte or page write operation.
After setting SDP, any attempt to write to the device without the three byte command
sequence will start the internal write timers. No data will be written to the device; however, for
the duration of t
WC, read operations will effectively be polling operations.
4.7
Device Identification
An extra 64 bytes of EEPROM memory are available to the user for device identification. By
raising A9 to 12V
± 0.5V and using address locations 7FC0H to 7FFFH the additional bytes
may be written to or read from in the same manner as the regular memory array.
4.8
Optional Chip Erase Mode
The entire device can be erased using a 6-byte software code. Please see “Software Chip
Erase” application note for details.
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PDF描述
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AT28HC256E-70JU 功能描述:電可擦除可編程只讀存儲(chǔ)器 256K 70ns RoHS:否 制造商:Atmel 存儲(chǔ)容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時(shí)鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8
AT28HC256E-70JU-T 功能描述:IC EEPROM 256KBIT 70NS 32PLCC 制造商:microchip technology 系列:- 包裝:剪切帶（CT） 零件狀態(tài):在售 存儲(chǔ)器類型:非易失 存儲(chǔ)器格式:EEPROM 技術(shù):EEPROM 存儲(chǔ)容量:256Kb （32K x 8） 寫周期時(shí)間 - 字，頁(yè):10ms 訪問(wèn)時(shí)間:70ns 存儲(chǔ)器接口:并聯(lián) 電壓 - 電源:4.5 V ~ 5.5 V 工作溫度:-40°C ~ 85°C（TC） 安裝類型:表面貼裝 封裝/外殼:32-LCC（J 形引線） 供應(yīng)商器件封裝:32-PLCC（11.43x13.97） 標(biāo)準(zhǔn)包裝:1
AT28HC256E-70PC 功能描述:電可擦除可編程只讀存儲(chǔ)器 256K HI-ENDURANCE SDP - 70NS COM TEMP RoHS:否 制造商:Atmel 存儲(chǔ)容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時(shí)鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8
AT28HC256E-70PI 功能描述:電可擦除可編程只讀存儲(chǔ)器 256K HI-ENDURANCE SDP - 70NS IND TEMP RoHS:否 制造商:Atmel 存儲(chǔ)容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時(shí)鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8
AT28HC256E-70SC 功能描述:電可擦除可編程只讀存儲(chǔ)器 256K HI-ENDURANCE SDP - 70NS COM TEMP RoHS:否 制造商:Atmel 存儲(chǔ)容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時(shí)鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8
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