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参数资料
| 型号： | DS3803 |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Static RAM |
| 英文描述： | 32K X 32 NON-VOLATILE SRAM MODULE, 70 ns, SMA72 |
| 封装： | SIMM-72 |
| 文件页数： | 3/10页 |
| 文件大小： | 231K |
| 代理商： | DS3803 |
DS3803
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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 (A0 -
A14) defines which byte of data is to be accessed from the selected SRAMs. Valid data will be available
to the data output drivers within tACC (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 tCO for CE or tOE for OE rather than tACC .
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
(tWR) 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 tODW from its falling edge.
DATA RETENTION MODE
The DS3803 provides full functional capability for VCC greater than 4.5 volts and write-protects by 4.25
volts. Data is maintained in the absence of VCC without any additional support circuitry. The nonvolatile
static RAM constantly monitors VCC. 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 VCC falls
below approximately 3.0 volts, power switching circuits connect the lithium energy sources to the RAMs
to retain data. During power-up, when VCC rises above approximately 3.0 volts, the power switching
circuits connect external VCC to the RAMs and disconnects the lithium energy source. Normal RAM
operation can resume after VCC exceeds 4.5 volts.
The DS3803 checks battery status to warn of potential data loss. Each time that VCC 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.
相关PDF资料 |
PDF描述 |
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| DS5001FP | 8-BIT, MICROCONTROLLER, PQFP80 |
| DS5002FP | 8-BIT, MICROCONTROLLER, PQFP80 |
| DS600U/T&R | ANALOG TEMP SENSOR-VOLTAGE, 0-0.4V, 0.75Cel, SQUARE, SURFACE MOUNT |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS3803-70 | 功能描述:IC NVSRAM 1MBIT 70NS 72SIMM RoHS:否 类别:集成电路 (IC) >> 存储器 系列:- 标准包装:150 系列:- 格式 - 存储器:EEPROMs - 串行 存储器类型:EEPROM 存储容量:4K (2 x 256 x 8) 速度:400kHz 接口:I²C，2 线串口 电源电压:2.5 V ~ 5.5 V 工作温度:-40°C ~ 85°C 封装/外壳:8-VFDFN 裸露焊盘 供应商设备封装:8-DFN（2x3） 包装:管件 产品目录页面:1445 (CN2011-ZH PDF) |
| DS3816C-512 | 制造商:未知厂家 制造商全称:未知厂家 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 制造商全称:Dallas Semiconductor 功能描述:3.3V, 32Mb Advanced NV SRAM with Clock |
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