參數(shù)資料
型號(hào)： R2051K
英文描述： real-time clock ICs
中文描述： 實(shí)時(shí)時(shí)鐘IC
文件頁(yè)數(shù)： 10/53頁(yè)
文件大?。?/td> 343K
代理商： R2051K
R2051 Series
I
GENERAL DESCRIPTION
G
Battery Backup Switchover Function
The R2051 Series have two power supply input, or VCC and VSB. With monitoring input voltage of VCC pin by
internal Voltage Detector, it is selected which power supply of VCC or VSB is used for the internal power source.
Refer to the next table to see the state of the backup battery and internal power supply’s state of the IC by each
condition.
VCC
≥
VDET1
VCC
<
VDET1
VCC
→
RTC, VDD
/VDCC=OFF(H)
/VDCC=L
As a backup battery, not only a primary battery such as CR2025, LR44, or a secondary battery such as ML614,
TC616, but also an electric double layered capacitor or an aluminum capacitor can be used. Switchover point is
judged with the voltage of the main power (VCC), therefore, if the backup voltage is higher than main supply voltage,
switchover can be realized without extra load to the backup power supply.
12345
Rev.1.04 - 10 -
VSB
→
RTC, VDD
VDD
VSB
VCC
VSS
0.1
μ
F
CPU Power
Supply
The case of back-up by
primary battery
CR2025
etc.
VSB
VDD
VCC
VSS
0.1
μ
F
CPU power
supply
ML614
etc.
The case of back-up by
capacitor or secondary battery
(Charging voltage is equal to CPU
power supply voltage)
VSB
VDD
VCC
VSS
0.1
μ
F
CPU power
supply
(3V)
5V
Double layer
capacitor
etc.
The case of back-up by
capacitor or secondary battery
(Charging voltage is not equal to
CPU power supply voltage)
Interface with CPU
The R2051 is connected to the CPU by two signal lines SCL and SDA, through which it reads and writes data from
and to the CPU. Since the output of the I/O pin of SDA is open drain, data interfacing with a CPU different supply
voltage is possible by applying pull-up resistors on the circuit board. The maximum clock frequency of 400kHz (at
VDD=3V) of SCL enables data transfer in I2C-Bus fast mode. VCC falls down under -VDET1, the R2051 stops
accessing with CPU.
G
Clock and Calendar Function
The R2051 reads and writes time data from and to the CPU in units ranging from seconds to the last two digits of
the calendar year. The calendar year will automatically be identified as a leap year when its last two digits are a
multiple of 4. Consequently, leap years up to the year 2099 can automatically be identified as such.
*) The year 2000 is a leap year while the year 2100 is not a leap year.
G
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
R2051K01-E2 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:2 wire interface Real-Time Clock ICs with Battery Backup switch-over Function
R2051K02-E2 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:2 wire interface Real-Time Clock ICs with Battery Backup switch-over Function
R2051S01-E2 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:2 wire interface Real-Time Clock ICs with Battery Backup switch-over Function
R2051S02-E2 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:2 wire interface Real-Time Clock ICs with Battery Backup switch-over Function
R2051S03-E2 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:2 wire interface Real-Time Clock ICs with Battery Backup switch-over Function
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