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參數(shù)資料
| 型號： | CDP1879CD1X |
| 廠商： | HARRIS SEMICONDUCTOR |
| 元件分類： | XO, clock |
| 英文描述： | IC LOGIC 16211 24-BIT FET BUS SWITCH -40+85C SSOP-56 26/TUBE |
| 中文描述： | 1 TIMER(S), REAL TIME CLOCK, CDIP24 |
| 文件頁數(shù)： | 12/18頁 |
| 文件大?。?/td> | 100K |
| 代理商： | CDP1879CD1X |
4-115
Design Considerations for Stable Crystal Oscillation
1. Stray capacitances should be minimized for best oscilla-
tor performance. Circuit board traces should be kept to a
maximum of 1 inch, and there should be no parallel
traces.
2. A signal line or power source line must not cross or go
near the oscillator circuit line.
3. It is advisable to put a 0.1
μ
F capacitor between V
DD
and
V
SS
of the CDP1879.
Standby (Timekeeping) Voltage Operation
When any one of the four specified crystals is used with the
on-board oscillator, the Real-Time Clock can operate at a
minimum of 4V V
DD
. However, at 32kHz the clock will run
(timekeeping only, no device READ/WRITE accesses) down
to 3V at -40
o
C to +85
o
C and 2.5V at 0
o
to +70
o
C.
To achieve this low voltage operation, an external 32kHz clock
source must be supplied at the XTAL input (see Figure 7). The
standby requirements for CHIP SELECT/DESELECT are
listed in Table 4, and Figure 8 indicates the timing waveforms.
Figure 9 illustrates the typical timekeeping curve over the full
temperature range.
TABLE 3. TYPICAL OSCILLATOR CIRCUIT PARAMETERS FOR SUGGESTED OSCILLATOR CIRCUIT, SEE FIGURE 6
PARAMETER
4.197MHz
2.097MHz
1.049MHz
32768Hz (NOTE)
UNITS
R
F
22
22
22
22
M
C
0
39
39
39
39
pF
C
1
5
5
5
5
pF
R
S
-
-
-
200
k
C
L
-
-
-
91
pF
Crystal Impedance
73
200
200
50K (max.)
NOTE:
CDP1879C-1 only.
FIGURE 5. CONNECTIONS FOR AN EXTERNAL FREQUENCY
SOURCE APPLIED TO REAL-TIME CLOCK
CDP1879
PIN 23
XTAL
EXTERNAL
FREQUENCY
SOURCE
PIN 22
XTAL
FIGURE 6. SUGGESTED OSCILLATOR CIRCUIT APPLIED TO
REAL-TIME CLOCK (SEE TABLE 3)
CDP1879
PIN 23
XTAL
PIN 22
PARALLEL
RESONANT
CRYSTAL
XTAL
R
S
C
L
C
O
C
I
R
F
5
P
F
200K
R
L
39
P
F
22 MEG.
R
F
1
2
3
14
4
+3V
24
23
22
1/3 CD54/74HC04
CDP1879
FIGURE 7. TYPICAL EXTERNAL CLOCK-SOURCE CIRCUIT
CDP1879, CDP1879C-1
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| CDP1879 | CMOS Real-Time Clock(CMOS 實時時鐘) |
| CDP1879E | CMOS Real-Time Clock |
| CDP1879CE1 | CMOS Real-Time Clock |
| CDP1881CE | CMOS 6-Bit Latch and Decoder Memory Interfaces |
| CDP1881C | CMOS 6-Bit Latch and Decoder Memory Interfaces(CMOS ６位鎖存和解碼存儲器接口) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| CDP1879CE1 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:CMOS Real-Time Clock |
| CDP1879D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Peripheral IC |
| CDP1879E | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| CDP1881C | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:CMOS 6-Bit Latch and Decoder Memory Interfaces |
| CDP1881CE | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:CMOS 6-Bit Latch and Decoder Memory Interfaces |
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