參數(shù)資料
| 型號： | X1286V14I |
| 廠商： | Intersil |
| 文件頁數(shù)： | 14/25頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC RTC/CAL/CPU SUP EE 14-TSSOP |
| 標準包裝： | 95 |
| 類型： | 時鐘/日歷 |
| 特點： | 警報器，閏年，監(jiān)控器，監(jiān)視計時器 |
| 時間格式： | HH:MM:SS:hh（12/24 小時） |
| 數(shù)據格式： | YY-MM-DD-dd |
| 接口： | I²C，2 線串口 |
| 電源電壓： | 2.7 V ~ 5.5 V |
| 電壓 - 電源，電池： | 1.8 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 14-TSSOP（0.173"，4.40mm 寬） |
| 供應商設備封裝： | 14-TSSOP |
| 包裝： | 管件 |
21
FN8101.1
April 14, 2006
A final application for the ATR control is in-circuit cali-
bration for high accuracy applications, along with a
temperature sensor chip. Once the RTC circuit is pow-
ered up with battery backup, the PHZ output is set at
32.768kHz and frequency drift is measured. The ATR
control is then adjusted to a setting which minimizes
drift. Once adjusted at a particular temperature, it is
possible to adjust at other discrete temperatures for
minimal overall drift, and store the resulting settings in
the EEPROM. Extremely low overall temperature drift
is possible with this method. The Intersil evaluation
board contains the circuitry necessary to implement
this control.
For more detailed operation see Intersil’s application
note AN154 on Intersil’s website at www.Intersil.com.
Layout Considerations
The crystal input at X1 has a very high impedance and
will pick up high frequency signals from other circuits on
the board. Since the X2 pin is tied to the other side of
the crystal, it is also a sensitive node. These signals can
couple into the oscillator circuit and produce double
clocking or mis-clocking, seriously affecting the accu-
racy of the RTC. Care needs to be taken in layout of the
RTC circuit to avoid noise pickup. Below in Figure 15 is
a suggested layout for the X1286 or X1288 devices.
Figure 15. Suggested Layout for Intersil RTC in SO-8
The X1 and X2 connections to the crystal are to be
kept as short as possible. A thick ground trace around
the crystal is advised to minimize noise intrusion, but
ground near the X1 and X2 pins should be avoided as
it will add to the load capacitance at those pins. Keep
in mind these guidelines for other PCB layers in the
vicinity of the RTC device. A small decoupling capaci-
tor at the Vcc pin of the chip is mandatory, with a solid
connection to ground.
The X1286 product has a special consideration. The
PHZ/IRQ- pin on the 8 Ld SOIC package is located
next to the X2 pin. When this pin is used as a fre-
quency output (PHZ) and is set to 32.768kHz output
frequency, noise can couple to the X1 or X2 pins and
cause double-clocking. The layout in figure 15 can
help minimize this by running the PHZ output away
from the X1 and X2 pins. Also, minimizing the switch-
ing current at this pin by careful selection of the pullup
resistor value will reduce noise. Intersil suggests a
minimum value of 5.1k for 32.768kHz, and higher val-
ues (i.e. 20k
) for lower frequency PHZ outputs.
For other RTC products, the same rules stated above
should be observed, but adjusted slightly since the
packages and pinouts are slightly different.
Assembly
Most electronic circuits do not have to deal with
assembly issues, but with the RTC devices assembly
includes insertion or soldering of a live battery into an
unpowered circuit. If a socket is soldered to the board,
and a battery is inserted in final assembly, then there
are no issues with operation of the RTC. If the battery
is soldered to the board directly, then the RTC device
Vback pin will see some transient upset from either
soldering tools or intermittent battery connections
which can stop the circuit from oscillating. Once the
battery is soldered to the board, the only way to assure
the circuit will start up is to momentarily (very short
period of time!) short the Vback pin to ground and the
circuit will begin to oscillate.
Oscillator Measurements
When a proper crystal is selected and the layout guide-
lines above are observed, the oscillator should start up
in most circuits in less than one second. Some circuits
may take slightly longer, but startup should definitely
occur in less than 5 seconds. When testing RTC cir-
cuits, the most common impulse is to apply a scope
probe to the circuit at the X2 pin (oscillator output) and
observe the waveform. DO NOT DO THIS! Although in
some cases you may see a useable waveform, due to
the parasitics (usually 10pF to ground) applied with the
scope probe, there will be no useful information in that
waveform other than the fact that the circuit is oscillat-
ing. The X2 output is sensitive to capacitive impedance
so the voltage levels and the frequency will be affected
by the parasitic elements in the scope probe. Applying a
scope probe can possibly cause a faulty oscillator to
start up, hiding other issues (although in the Intersil
RTC’s, the internal circuitry assures startup when using
the proper crystal and layout).
The best way to analyze the RTC circuit is to power it
up and read the real time clock as time advances, or if
the chip has the PHZ output, look at the output of that
pin on an oscilloscope (after enabling it with the con-
trol register, and using a pullup resistor for an open-
drain output). Alternatively, the X1226/X1286/1288
C1
0.1F
XTAL1
U1
R1 10k
X1286/X1288
32.768kGz
X1286
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| X1286V14IT1 | 功能描述:IC RTC/CAL/CPU SUP EE 14-TSSOP RoHS:否 類別:集成電路 (IC) >> 時鐘/計時 - 實時時鐘 系列:- 產品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:- 類型:時鐘/日歷 特點:警報器，閏年，SRAM 存儲容量:- 時間格式:HH:MM:SS（12/24 小時） 數(shù)據格式: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 供應商設備封裝:8-TDFN EP 包裝:管件 |
| X1286V14IZ | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Intersil Real Time Clock/Calendar/CPU Supervisor with EEPROM |
| X1286V14T1 | 功能描述:IC RTC/CAL/CPU SUP EE 14-TSSOP RoHS:否 類別:集成電路 (IC) >> 時鐘/計時 - 實時時鐘 系列:- 產品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:- 類型:時鐘/日歷 特點:警報器，閏年，SRAM 存儲容量:- 時間格式:HH:MM:SS（12/24 小時） 數(shù)據格式: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 供應商設備封裝:8-TDFN EP 包裝:管件 |
| X1286V14Z | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Intersil Real Time Clock/Calendar/CPU Supervisor with EEPROM |
| X1288 | 制造商:XICOR 制造商全稱:Xicor Inc. 功能描述:2-Wire RTC Real Time Clock/Calendar/CPU Supervisor with EEPROM |
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