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參數(shù)資料
| 型號(hào)： | DS1742W-150 |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Timer or RTC |
| 英文描述： | 0 TIMER(S), REAL TIME CLOCK, DMA24 |
| 封裝： | DIP-24 |
| 文件頁(yè)數(shù)： | 7/12頁(yè) |
| 文件大?。?/td> | 162K |
| 代理商： | DS1742W-150 |
DS1742
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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 DS1742 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 transition of WE , on 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
The 5-volt device is fully accessible and data can be written or read only when VCC is greater than VPF.
However, when VCC is below the power fail point, VPF, (point at which write protection occurs) the
internal clock registers and SRAM are blocked from any access. When VCC falls below the battery switch
point VSO (battery supply level), device power is switched from the VCC pin to the backup battery. RTC
operation and SRAM data are maintained from the battery until VCC is returned to nominal levels. The 3.3
volt device is fully accessible and data can be written or read only when VCC is greater than VPF. When VCC
falls below the power fail point, VPF, access to the device is inhibited. If VPF is less than Vso, the device
power is switched from VCC to the backup supply (VBAT) when VCC drops below VPF. If VPF is greater than
Vso, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below Vso. RTC
operation and SRAM data are maintained from the battery until VCC is returned to nominal levels.
BATTERY LONGEVITY
The DS1742 has a lithium power source that is designed to provide energy for clock activity, and clock
and RAM data retention when the VCC supply is not present. The capability of this internal power supply
is sufficient to power the DS1742 continuously for the life of the equipment in which it is installed. For
specification purposes, the life expectancy is 10 years at 25
°C with the internal clock oscillator running in
the absence of VCC power. Each DS1742 is shipped from Dallas Semiconductor with its lithium energy
source disconnected, guaranteeing full energy capacity. When VCC is first applied at a level greater than
VPF, the lithium energy source is enabled for battery backup operation. Actual life expectancy of the
DS1742 will be much longer than 10 years since no lithium battery energy is consumed when VCC is
present.
BATTERY MONITOR
The DS1742 constantly monitors the battery voltage of the internal battery. The Battery Flag bit (bit 7) of
the day register is used to indicate the voltage level range of the battery. This bit is not writable and
should always be a 1 when read. If a 0 is ever present, an exhausted lithium energy source is indicated
and both the contents of the RTC and RAM are questionable.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS1743P-70 | 0 TIMER(S), REAL TIME CLOCK, DMA34 |
| DS1743-70 | 0 TIMER(S), REAL TIME CLOCK, DMA28 |
| DS1743W-120 | 0 TIMER(S), REAL TIME CLOCK, DMA28 |
| DS9034PCX | 0 TIMER(S), REAL TIME CLOCK, DMA34 |
| DS1743-100 | 0 TIMER(S), REAL TIME CLOCK, DMA28 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS1742W-150+ | 功能描述:實(shí)時(shí)時(shí)鐘 Timekeeping NV RAM RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS1743 | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Y2K-Compliant, Nonvolatile Timekeeping |
| DS1743-100 | 功能描述:實(shí)時(shí)時(shí)鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS1743-100 IND | 功能描述:實(shí)時(shí)時(shí)鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS1743-100+ | 功能描述:實(shí)時(shí)時(shí)鐘 Timekeeping NV RAM RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
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