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参数资料
| 型号： | DS1647 |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Timer or RTC |
| 英文描述： | 0 TIMER(S), REAL TIME CLOCK, DMA32 |
| 封装： | PLASTIC, MODULE, DIP-32 |
| 文件页数： | 7/11页 |
| 文件大小： | 187K |
| 代理商： | DS1647 |
DS1647/DS1647P
5 of 11
RETRIEVING DATA FROM RAM OR CLOCK
The DS1647 is in the read mode whenever WE (write enable) is high; CE (chip enable) is low. The
device architecture allows ripple-through access to any of the address locations in the NV SRAM. Valid
data will be available at the DQ pins within tAA after the last address input is stable, providing that the CE
and OE access times and states are satisfied. If CE or OE access times are not met, valid data will be
available at the latter of chip-enable access (tCEA) or at output enable access time (tOEA). The state of the
data input/output pins (DQ) is controlled by CE and OE . If the outputs are activated before tAA, the data
lines are driven to an intermediate state until tAA. If the address inputs are changed while CE and OE
remain valid, output data will remain valid for output data hold time (tOH) but will then go indeterminate
until the next address access.
WRITING DATA TO RAM OR CLOCK
The DS1647 is in the write mode whenever WE and CE are in their active state. The start of a write is
referenced to the latter occurring high to low transition of WE and CE . The addresses must be held valid
throughout the cycle. CE or WE must return inactive for a minimum of tWR prior to the initiation of
another read or write cycle. Data in must be valid tDS prior to the end of write and remain valid for tDH
afterward. In a typical application, the OE signal will be high during a write cycle. However, OE can be
active provided that care is taken with the data bus to avoid bus contention. If OE is low prior to WE
transitioning low the data bus can become active with read data defined by the address inputs. A low
transition on WE will then disable the outputs tWEZ after WE goes active.
DATA RETENTION MODE
When VCC is within nominal limits (VCC > 4.5 volts) the DS1647 can be accessed as described above with
read or write cycles. However, when VCC is below the power-fail point VPF (point at which write
protection occurs) the internal clock registers and RAM are blocked from access. This is accomplished
internally by inhibiting access via the CE signal. At this time the power-fail output signal ( PFO ) will be
driven active low and will remain active until VCC returns to nominal levels. When VCC falls below the
level of the internal battery supply, power input is switched from the VCC pin to the internal battery and
clock activity, RAM, and clock data are maintained from the battery until VCC is returned to nominal
level.
相关PDF资料 |
PDF描述 |
|---|---|
| DS1670 | 0 TIMER(S), REAL TIME CLOCK, PDSO20 |
| DS1672-2 | 0 TIMER(S), REAL TIME CLOCK, PDIP8 |
| DS1672-33 | 0 TIMER(S), REAL TIME CLOCK, PDIP8 |
| DS1672S-33 | 0 TIMER(S), REAL TIME CLOCK, PDSO8 |
| DS1672-3 | 0 TIMER(S), REAL TIME CLOCK, PDIP8 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1647-12 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:NVRAM (Battery Based) |
| DS1647-120 | 功能描述:实时时钟 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS1647-120+ | 功能描述:实时时钟 NV Timekeeping RAM RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS1647-15 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:NVRAM (Battery Based) |
| DS1647D | 制造商:未知厂家 制造商全称:未知厂家 功能描述:4-Bit Bus Transceiver |
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