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參數(shù)資料
| 型號： | XRK4991ACJ-5 |
| 廠商： | EXAR CORP |
| 元件分類： | 時鐘及定時 |
| 英文描述： | 3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER |
| 中文描述： | 4991 SERIES, PLL BASED CLOCK DRIVER, 8 TRUE OUTPUT(S), 0 INVERTED OUTPUT(S), PQCC32 |
| 封裝： | PLASTIC, LCC-32 |
| 文件頁數(shù)： | 5/13頁 |
| 文件大?。?/td> | 255K |
| 代理商： | XRK4991ACJ-5 |
xr
REV. P1.0.2
PRELIMINARY
3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER
XRK4991A
5
SKEW SELECT MATRIX
The skew select matrix is comprised of four independent sections. Each section has two low-skew, high-fanout
drivers (Qx[0:1]), and two corresponding three-level function select (SELx[0:1]) inputs. Table 2 below shows
the nine possible output functions for each section as determined by the function select inputs. All times are
measured with respect to the CLKIN input assuming that the output connected to the FB_IN input has 0t
U
selected.
N
OTES
:
1.
For all three-state inputs, HIGH indicates a connection to V
CC
, LOW indicates a connection to GND, and MID
indicates an open connection. Internal termination circuitry holds an unconnected input to V
CC
/2.
The level to be set on FSEL is determined by the “normal” operating frequency (f
NOM
) of the V
CO
and Time Unit
Generator (see Logic Block Diagram). Nominal frequency (f
NOM
) always appears at QA0 and the other outputs
when they are operated in their undivided modes (see Table 2). The frequency appearing at the CLKIN and FB_IN
inputs will be f
NOM
when the output connected to FB_IN is undivided. The frequency of the CLKIN and FB_IN
inputs will be f
NOM
/2 or f
NOM
/4 when the part is configured for a frequency multiplication by using a divided output
as the FB_IN input.
When the FSEL pin is selected HIGH, the CLKIN input must not transition upon power-up until V
CC
has reached
2.8V.
2.
3.
T
ABLE
2: F
REQUENCY
R
ANGE
S
ELECT
AND
t
U
C
ALCULATION
[1]
f
NOM
(MH
Z
)
t
U
= 1 /
f
NOM X
N
A
PPROXIMATE
F
REQUENCY
(MH
Z
)
AT
WHICH
t
U
= 1.0ns
FSEL
[2,3]
M
IN
M
AX
WHERE
N =
LOW
15
30
44
22.7
MID
25
50
26
38.5
HIGH
40
85
16
62.5
T
ABLE
3: P
ROGRAMMABLE
S
KEW
C
ONFIGURATIONS
[1]
F
UNCTION
S
ELECTS
O
UTPUT
F
UNCTIONS
SEL
X
1
SEL
X
0
QA[1:0], QB[1:0]
QC[1:0]
QD[1:0]
LOW
LOW
-4t
U
Divide by 2
Divide by 2
LOW
MID
-3t
U
-6t
U
-6t
U
LOW
HIGH
-2t
U
-4t
U
-4t
U
MID
LOW
-1t
U
-2t
U
-2t
U
MID
MID
0t
U
0t
U
0t
U
MID
HIGH
+1t
U
+2t
U
+2t
U
HIGH
LOW
+2t
U
+4t
U
+4t
U
HIGH
MID
+3t
U
+6t
U
+6t
U
HIGH
HIGH
+4t
U
Divide by 4
Inverted
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| XRK4991ACJ-7 | 制造商:EXAR 制造商全稱:EXAR 功能描述:3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER |
| XRK4991AIJ-5 | 制造商:EXAR 制造商全稱:EXAR 功能描述:3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER |
| XRK4991AIJ-7 | 制造商:EXAR 制造商全稱:EXAR 功能描述:3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER |
| XRK4991CJ-2 | 制造商:EXAR 制造商全稱:EXAR 功能描述:3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER |
| XRK4991CJ-5 | 制造商:EXAR 制造商全稱:EXAR 功能描述:3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER |
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