The 5V device is fully accessible and data can be written or read only when V
參數(shù)資料
型號(hào)： DS1244WP-120IND
廠商： Maxim Integrated Products
文件頁(yè)數(shù)： 16/20頁(yè)
文件大小： 0K
描述： IC NVSRAM 256KBIT 120NS 34PCM
標(biāo)準(zhǔn)包裝： 40
類型： Phantom 計(jì)時(shí)芯片
特點(diǎn)： 閏年，NVSRAM
存儲(chǔ)容量： 32KB
時(shí)間格式： HH:MM:SS:hh（12/24 小時(shí)）
數(shù)據(jù)格式： YY-MM-DD-dd
接口： 并聯(lián)
電源電壓： 2.97 V ~ 3.63 V
電壓 - 電源，電池： 3V
工作溫度： -40°C ~ 85°C
安裝類型： 表面貼裝
封裝/外殼： 34-PowerCap? 模塊
供應(yīng)商設(shè)備封裝： 34-PowerCap 模塊
包裝： 管件
DS1244/DS1244P
5 of 20
DATA RETENTION MODE
The 5V 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 3.3V device is fully accessible and data can be written or read only when VCC is greater than VPF.
When VCC fall as below the VPF, access to the device is inhibited. If VPF is less than VBAT, the device
power is switched from VCC to the backup supply (VBAT ) when VCC drops below VPF. If VPF is greater
than VBAT, the device power is switched from VCC to the backup supply (VBAT ) when VCC drops below
VBAT. RTC operation and SRAM data are maintained from the battery until VCC is returned to nominal
levels.
All control, data, and address signals must be powered down when VCC is powered down.
PHANTOM CLOCK OPERATION
Communication with the phantom clock is established by pattern recognition on a serial bit stream of
64 bits, which must be matched by executing 64 consecutive write cycles containing the proper data on
DQ0. All accesses that occur prior to recognition of the 64-bit pattern are directed to memory.
After recognition is established, the next 64 read or write cycles either extract or update data in the
phantom clock, and memory access is inhibited.
Data transfer to and from the timekeeping function is accomplished with a serial bit stream under control
of the chip enable, output enable, and write enable. Initially, a read cycle to any memory location using
the CE and OE control of the phantom clock starts the pattern recognition sequence by moving a pointer
to the first bit of the 64-bit comparison register. Next, 64 consecutive write cycles are executed using the
CE
and WE control of the SmartWatch. These 64 write cycles are used only to gain access to the
phantom clock. Therefore, any address to the memory in the socket is acceptable. However, the write
cycles generated to gain access to the phantom clock are also writing data to a location in the mated
RAM. The preferred way to manage this requirement is to set aside just one address location in RAM as a
phantom clock scratch pad. When the first write cycle is executed, it is compared to bit 0 of the 64-bit
comparison register. If a match is found, the pointer increments to the next location of the comparison
register and awaits the next write cycle. If a match is not found, the pointer does not advance and all
subsequent write cycles are ignored. If a read cycle occurs at any time during pattern recognition, the
present sequence is aborted and the comparison register pointer is reset. Pattern recognition continues for
a total of 64 write cycles as described above until all the bits in the comparison register have been
matched (Figure 1). With a correct match for 64 bits, the phantom clock is enabled and data transfer to or
from the timekeeping registers can proceed. The next 64 cycles will cause the phantom clock to either
receive or transmit data on DQ0, depending on the level of the OE pin or the WE pin. Cycles to other
locations outside the memory block can be interleaved with CE cycles without interrupting the pattern
recognition sequence or data transfer sequence to the phantom clock.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS1244WP-120IND+ 功能描述:實(shí)時(shí)時(shí)鐘 256k NV SRAM w/Phantom Clock 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
DS1244Y 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:Real Time Clock, Non-Volatile, 28 Pin, Plastic, DIP
DS1244Y120 制造商:Maxim Integrated Products 功能描述:
DS1244Y-120 制造商:Maxim Integrated Products 功能描述:
DS1244Y-150 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
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