參數(shù)資料
型號(hào)： DS87C530-ENL
英文描述： EPROM MICRO WITH REAL TIME CLOCK
中文描述： 微型存儲(chǔ)器與實(shí)時(shí)時(shí)鐘
文件頁數(shù)： 9/40頁
文件大小： 435K
代理商： DS87C530-ENL
DS87C530
022197 9/40
NONVOLATILE RAM
The 1K x 8 on–chip SRAM can be nonvolatile. An exter-
nal backup energy–source will maintain the SRAM con-
tents through power failure. This allows the DS87C530
to log data or to store configuration settings. Internal
switching circuits will detect the loss of V
CC
and switch
SRAM power to the backup source on the V
BAT
pin. The
256 bytes of direct RAM are not affected by this circuit
and are volatile.
CRYSTAL AND BACKUP SOURCES
To use the unique functions of the DS87C530, two
external components are needed. These are a 32.768
KHz timekeeping crystal and a backup energy–source.
The following describes guidelines for choosing these
devices.
Timekeeping Crystal
The DS87C530 can use a standard 32.768 KHz crystal
as the RTC time base. There are two versions of stan-
dard crystals available, with 6 pF and 12.5 pF load
capacitance. The tradeoff is that the 6 pF uses less
power, giving longer life while V
CC
is off, but is more sen-
sitive to noise and board layout. The 12.5 pF crystal
uses more power, giving a shorter battery backed life,
but produces a more robust oscillator. Bit 6 in the RTC
Trim register (TRIM; 96h) must be programmed to spec-
ify the crystal type for the oscillator. When TRIM.6 = 1,
the circuit expects a 12.5 pF crystal. When TRIM.6 = 0, it
expects a 6 pF crystal. As mentioned above, this bit will
be nonvolatile so these choices will remain while the
backup source is present. A guard ring (connected to
the Real Time Clock ground) should encircle the RTCX1
and RTCX2 pins.
Backup Energy Source
The DS87C530 uses an external energy source to
maintain timekeeping and SRAM data without V
CC
. This
source can be either a battery or 0.47 F super cap and
should be connected to the V
BAT
pin. The nominal bat-
tery voltage is 3V. The V
BAT
pin will not source current.
Therefore, a super cap requires an external resistor and
diode to supply charge.
The backup lifetime is a function of the battery capacity
and the data retention current drain. This drain is speci-
fied in the electrical specifications. The circuit loads the
V
BAT
only when V
CC
has fallen below V
BAT
. Thus the
actual lifetime depends not only on the current and bat-
tery capacity, but also on the portion of time without
power. A very small lithium cell provides a lifetime of
more than 10 years.
相關(guān)PDF資料
PDF描述
DS87C530-KCL EPROM MICRO WITH REAL TIME CLOCK
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS87C530-ENL+ 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:EPROM/ROM Microcontrollers with Real-Time Clock
DS87C530-KCL 功能描述:8位微控制器 -MCU EPROM MCU w/RTC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
DS87C530-QCL 功能描述:8位微控制器 -MCU EPROM MCU w/RTC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
DS87C530-QCL+ 功能描述:8位微控制器 -MCU EPROM MCU w/RTC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
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