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參數(shù)資料
| 型號： | FM3808 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 元件分類： | DRAM |
| 英文描述： | 4Kb FRAM Serial 3V Memory |
| 中文描述： | 4Kb的鐵電串行3V的記憶 |
| 文件頁數(shù)： | 19/28頁 |
| 文件大小： | 191K |
| 代理商： | FM3808 |
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FM3808
Rev 1.1
May 2003
Page 19 of 28
IBAK vs VBAK
0.0E+00
5.0E-07
1.0E-06
1.5E-06
2.0E-06
2.5E-06
4.7
4.5
4.25
4
3.75
3.5
3.25
3
2.75
2.5
VBAK
I
Figure 10. Backup Current vs. Voltage
Crystal Selection
The second passive component needed for the RTC
function is the timekeeping crystal. A 32.768 kHz
time-base is required, and the FM3808 is designed to
accept a low cost crystal. The major parameters
associated with the crystal are timekeeping accuracy
and backup current. The FM3808 is designed to
accept a crystal with a characteristic capacitance of 6
pF. Deviations from this specification will lead to
different accuracy and IBAK from the specified
values. Though accuracy is unlikely to improve, the
IBAK may go up or down from the specified value as
a function of the capacitive load.
The timekeeping accuracy is also a strong function of
the operating temperature due to errors in crystal
frequency. Temperature behavior of timekeeping
crystals is well known and it follows a curve like the
one shown below. The specific crystal manufacturer
should be consulted for the behavior of their specific
device. Note the error in frequency ppm. One ppm is
roughly 2.6 seconds per month in timekeeping error.
-200
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
-
-
-
-
-
5
1
2
3
4
5
6
7
8
Ambient Temperature
C
E
Figure 11. Typical Crystal Error vs. Temperature
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| FM3808-70-T | 4Kb FRAM Serial 3V Memory |
| FM3808DK | 4Kb FRAM Serial 3V Memory |
| FMA10A | General Purpose(Dual Digital Transistor)(通用(雙數(shù)字晶體管)) |
| FMA11A | Emitter Common (Dual Digital Transistors)(公共發(fā)射級(雙數(shù)字晶體管)) |
| FMA1 | General purpose (dual digital transistors) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| FM3808_06 | 制造商:RAMTRON 制造商全稱:RAMTRON 功能描述:256Kb Bytewide FRAM w/ Real-Time Clock |
| FM3808-70-T | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:256Kb Bytewide FRAM w/ Real-Time Clock |
| FM3808DK | 制造商:RAMTRON 制造商全稱:RAMTRON 功能描述:256Kb Bytewide FRAM w/ Real-Time Clock |
| FM3808-S | 制造商:Ramtron International Corporation 功能描述:FRAM RTC 256K SMD 3808 TSOP32 |
| FM3808-SG | 制造商:Ramtron International Corporation 功能描述:FRAM RTC 256K SMD 3808 TSOP32 |
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