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參數(shù)資料
| 型號： | DS17487B-3 |
| 英文描述： | 3V/5V Real-Time Clock |
| 中文描述： | 3V/5V實(shí)時時鐘 |
| 文件頁數(shù)： | 16/38頁 |
| 文件大?。?/td> | 427K |
| 代理商： | DS17487B-3 |
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DS17485/DS17487
16 of 38
EXTENDED FUNCTIONS
The extended functions provided by the DS17485/DS17487 that are new to the RAMified RTC family
are accessed by a software-controlled bank-switching scheme, as illustrated in Figure 4. In bank 0, the
clock/calendar registers and 50 bytes of user RAM are in the same locations as for the DS1287. As a
result, existing routines implemented within BIOS, DOS, or application software packages can gain
access to the DS17485/DS17487 clock registers with no changes. Also in bank 0, an extra 64 bytes of
RAM are provided at addresses just above the original locations for a total of 114 directly addressable
bytes of user RAM.
When bank 1 is selected, the clock/calendar registers and the original 50 bytes of user RAM still appear
as bank 0. However, the Dallas registers that provide control and status for the extended functions are
accessed in place of the additional 64 bytes of user RAM. The major extended functions controlled by the
Dallas registers are listed below:
64-bit Silicon Serial Number
Century Counter
RTC Write Counter
Date Alarm
Auxiliary Battery Control/Status
Wake-Up
Kickstart
RAM Clear Control/Status
4kB Extended RAM Access
The bank selection is controlled by the state of the DV0 bit in register A. To access bank 0 the DV0 bit
should be written to a 0. To access bank 1, DV0 should be written to a 1. Register locations designated as
reserved in the bank 1 map are reserved for future use by Dallas Semiconductor. Bits in these locations
cannot be written and return a 0 if read.
Silicon Serial Number
A unique 64-bit lasered serial number is located in bank 1, registers 40h–47h. This serial number is
divided into three parts. The first byte in register 40h contains a model number to identify the device type
of the DS17485/DS17487. Registers 41h–46h contain a unique binary number. Register 47h contains a
CRC byte used to validate the data in registers 40h–46h. All 8 bytes of the serial number are read-only
registers.
The DS17485/DS17487 is manufactured such that no two devices contain an identical number in
locations 41h–47h.
Century Counter
A register has been added in bank 1, location 48H, to keep track of centuries. The value is read in either
binary or BCD according to the setting of the DM bit.
RTC Write Counter
An 8-bit counter located in extended register bank 1, 5Eh, counts the number of times the RTC is written
to. This counter is incremented on the rising edge of the
WR
signal every time that the
CS
signal
qualifies it. This counter is a read-only register and rolls over after 256 RTC write pulses. This counter
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS17487B-5 | 3V/5V Real-Time Clock |
| DS17487BN-3 | 3V/5V Real-Time Clock |
| DS17487BN-5 | 3V/5V Real-Time Clock |
| DS17487N-3 | 3V/5V Real-Time Clock |
| DS17487N-5 | 49.9 1% 1/4W 1206 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS17487B-5 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock |
| DS17487BN-3 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock |
| DS17487BN-5 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock |
| DS17487N-3 | 功能描述:IC RTC 3V 4K NV RAM 24-EDIP RoHS:否 類別:集成電路 (IC) >> 時鐘/計(jì)時 - 實(shí)時時鐘 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 類型:時鐘/日歷 特點(diǎn):警報(bào)器，閏年，SRAM 存儲容量:- 時間格式:HH:MM:SS（12/24 小時） 數(shù)據(jù)格式:YY-MM-DD-dd 接口:SPI 電源電壓:2 V ~ 5.5 V 電壓 - 電源，電池:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-WDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:8-TDFN EP 包裝:管件 |
| DS17487N-5 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock |
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