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参数资料
| 型号： | DS1215 |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | XO, clock |
| 英文描述： | Using the Dallas Phantom Real Time Clocks(实时时钟芯片) |
| 中文描述： | 0 TIMER(S), REAL TIME CLOCK, PDIP16 |
| 文件页数： | 5/13页 |
| 文件大小： | 64K |
| 代理商： | DS1215 |
APPLICATION NOTE 52
022394 5/13
RAM is losing data when powered down.
This problem can occur especially in NMOS processors
which become unstable at a higher voltage than CMOS
processors. This problem manifests itself in the method
in which power fail is determined. Write protection is
asserted when V
CC
drops below V
TP
, which is equal to
1.26 x V
BAT
. Typically, the battery has a voltage of ~3.0V
which leads to a V
TP
of 3.78V. Therefore, in a power
down situation, if the processor becomes unstable at a
V
CC
of greater than ~3.78V (which is often the case for
an NMOS processor), a spurious write cycle could cor-
rupt the data in the Phantom Clock. The solution to this
problem is to ensure that the processor is reset before it
becomes unstable and thus prevent any unwanted
writes from being executed. This can be accomplished
by monitoring V
CC
by one of Dallas Semiconductor’s
power monitors (the DS123X family) which generate a
reset signal when V
CC
is out of tolerance.
Can not read consecutive hundredths of
seconds.
It is not possible to read consecutive hundredths of
seconds because the access time to read the clock reg-
isters is too long.
COMMON PITFALLS
Device needs separate read and write signals. The Dal-
las Phantom Real Time Clocks were designed with Intel
timing in mind. Therefore it is necessary to have sepa-
rate read and write signals. It should be further stressed
that simply complementing one signal to arrive at the
other is not sufficient because this will cause the pattern
match pointer to be reset during each write cycle since
the OE signal will toggle whenever the WE signal
toggles.
Battery attachment (DS1215). Any battery attached to
the BAT1 or BAT2 pins must be connected directly to the
pin. It should be noted that a diode should not be con-
nected between the battery input pin and the battery.
This is not necessary because internal reverse charging
current protection circuitry is provided and is UL recog-
nized (#E99151).
ROM/RAM pin (DS1215). Insure that the ROM/RAM pin
is set to the correct value.
Reading and writing to clock registers. It is important
that all 64 bits be read or written to when the clock regis-
ters have been accessed. If this is not done, the device
will remain in the clock access mode.
Do not water wash DS1216 Intelligent Sockets. Water
washing for flux removal must not be performed on the
DS1216 Intelligent Sockets because contaminants in
the water can cause discharging of the internal lithium
energy source.
Crystal selection (DS1215). A 32.768 kHz quartz crys-
tal, Seiko part number DS–VT–200, Daiwa part number
DT–26S, or equivalent should be used. The crystal
selected for use must have a specified load capacitance
of 6 pF. The use of an incorrect crystal can kill the oscil-
lator or cause accuracy problems. Also, the use of an
external trim capacitor to adjust the oscillator is discour-
aged.
It is recommended that one of the Dallas SmartWatch or
Nonvolatile SRAM with Phantom Time Clock devices be
selected for the highest accuracy (
±
1 minute/month).
相关PDF资料 |
PDF描述 |
|---|---|
| DS1216B | SmartWatch/RAM 16K/64K(16K/64K位带实时时钟的掉电保护RAM插座) |
| DS1216C | SmartWatch/RAM 16K/65K(16K/65K位带实时时钟的掉电保护RAM插座) |
| DS1216D(中文) | Using the Dallas Phantom Real Time Clocks(256K/1M位带实时时钟的带掉电保护SRAM插座) |
| DS1216D | Using the Dallas Phantom Real Time Clocks(256K/1M位带实时时钟的带掉电保护SRAM插座) |
| DS1216E | SmartWatch/RAM 16K/66K(16K/66K带实时时钟的ROM或掉电保护RAM插座) |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1215G | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Peripheral IC |
| DS1215GN | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Peripheral IC |
| DS-1215ZJ | 制造商:Hikvision USA 功能描述:Camera Pole Mount Plate7.64In X 4.61In X 3.94In 制造商:HIKVISION 功能描述:CAMERA POLE MOUNT PLATE 7.64IN X 4.61IN X 3.94IN |
| DS1216 | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:SmartWatch RAM (DS1216B/C/D/H); SmartWatch ROM (DS1216E/F) |
| DS1216B | 功能描述:存储器控制器 SmartWatch RAM RoHS:否 制造商:Maxim Integrated |
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