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參數(shù)資料
| 型號(hào)： | DS3803 |
| 英文描述： | 1024k Flexible NV SRAM SIMM |
| 中文描述： | 1024k靈活的非易失SRAM上海藥物研究所 |
| 文件頁數(shù)： | 2/10頁 |
| 文件大?。?/td> | 231K |
| 代理商： | DS3803 |
DS3803
2 of 10
READ MODE
The DS3803 executes a read cycle whenever
WE
(Write enable) is inactive (high) and
CE
(Chip Enable)
and
OE
(Output Enable) are active (low). The unique address specified by the 15 address inputs (A
0
-
A
14
) defines which byte of data is to be accessed from the selected SRAMs. Valid data will be available
to the data output drivers within t
ACC
(Access Time) after the last address input signal is stable, providing
that
CE
and
OE
(Output Enable) access times are also satisfied. If
CE
and
OE
access times are not
satisfied, then data access must be measured from the later occurring signal and the limiting parameter is
either t
CO
for
CE
or t
OE
for
OE
rather than t
ACC
.
WRITE MODE
The DS3803 executes a write cycle whenever both
WE
and
CE
signals are in the active (low) state after
address inputs are stable. The later occurring falling edge of
CE
or
WE
will determine the start of the
write cycle. The write cycle is terminated by the earlier rising edge of
CE
or
WE
. All address inputs must
be kept valid throughout the write cycle.
WE
must return to the high state for a minimum recovery time
(t
WR
) before another cycle can be initiated. The
OE
control signal should be kept inactive (high) during
write cycles to avoid bus contention. However, if the output drivers are enabled (
CE
and
OE
active),
then
WE
will disable the outputs in t
ODW
from its falling edge.
DATA RETENTION MODE
The DS3803 provides full functional capability for V
CC
greater than 4.5 volts and write-protects by 4.25
volts. Data is maintained in the absence of V
CC
without any additional support circuitry. The nonvolatile
static RAM constantly monitors V
CC
. Should the supply voltage decay, the NV SRAM automatically
write-protects itself, all inputs become don’t care, and all outputs become high impedance. As V
CC
falls
below approximately 3.0 volts, power switching circuits connect the lithium energy sources to the RAMs
to retain data. During power-up, when V
CC
rises above approximately 3.0 volts, the power switching
circuits connect external V
CC
to the RAMs and disconnects the lithium energy source. Normal RAM
operation can resume after V
CC
exceeds 4.5 volts.
The DS3803 checks battery status to warn of potential data loss. Each time that V
CC
power is restored to
the DS3803, the battery voltages are checked with precision comparators. If both batteries providing
backup power to a particular SRAM are less than 2.0 volts, the second memory access to that SRAM is
inhibited. Battery status for each SRAM can therefore be determined by a three-step process. First, a read
cycle is performed to any location within that SRAM in order to save the contents of that location. A
subsequent write cycle can then be executed to the same memory location, altering data. If a subsequent
read cycle fails to verify the written data, then battery voltage for that SRAM is less than 2.0V and data is
in danger of being lost.
The DS3803 also provides battery redundancy. In many applications data integrity is paramount. The
DS3803 provides two batteries for each SRAM and an internal isolation switch to select between them.
During battery backup, the battery with the highest voltage is selected for use. If one battery fails, the
other automatically takes over. The switch between batteries is transparent to the user.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS3893AVX | 4-Bit Bus Transceiver |
| DS3893V | 4-Bit Bus Transceiver |
| DS3896J | Single 8-Bit Inverting Bus Transceiver |
| DS3897J | 4-Bit Bus Transceiver |
| DS3897MX | 4-Bit Bus Transceiver |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS3803-70 | 功能描述:IC NVSRAM 1MBIT 70NS 72SIMM RoHS:否 類別:集成電路 (IC) >> 存儲(chǔ)器 系列:- 標(biāo)準(zhǔn)包裝:150 系列:- 格式 - 存儲(chǔ)器:EEPROMs - 串行 存儲(chǔ)器類型:EEPROM 存儲(chǔ)容量:4K (2 x 256 x 8) 速度:400kHz 接口:I²C，2 線串口 電源電壓:2.5 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 封裝/外殼:8-VFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:8-DFN（2x3） 包裝:管件 產(chǎn)品目錄頁面:1445 (CN2011-ZH PDF) |
| DS3816C-512 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:16Mb Advanced NV SRAM with Clock |
| DS382 | 制造商:Miyama Electric 功能描述: |
| DS3821 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| DS3832C-311 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3.3V, 32Mb Advanced NV SRAM with Clock |
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