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I2779A-08ST View Datasheet(PDF) - Alliance Semiconductor

Part NameDescriptionManufacturer
I2779A-08ST Low-Cost Notebook EMI Reduction IC ALSC
Alliance Semiconductor ALSC
I2779A-08ST Datasheet PDF : 8 Pages
1 2 3 4 5 6 7 8
June 2005
rev 0.1
Pin Configuration
Pin Description
XIN/ CLKIN 1
XOUT 2
PD 3
LF 4
8 VDD
7 REF
P2779A
6 ModOUT
5 VSS
P2779A
Pin#
Pin Name Type
Description
1
XIN / CLKIN
I
Connect to crystal or clock input.
2
XOUT
O
Crystal output.
3
PD
I
Power-down control pin. Pull low to enable power-down mode.
This pin has an internal pull-up resistor.1
External loop filter for the PLL. By changing the value of the CRC circuit,
4
LF
I
the percentage spread can be adjusted accordingly.
(See Loop Filter Selection Table for detail values.)
5
VSS
P
Ground connection. Connect to system ground.
6
ModOUT
O
Spread spectrum clock output.
7
REF
O
Provides a reference clock output of the input frequency.
8
VDD
P
Connect to +3.3 V.
Note: 1. Connect to VDD if not used.
Loop Filter Selection Table VDD 3.3 V
Pin 4 LF
R1
C2
C1
Input FS1 FS0
BW = ± 0.50%
BW = ± 0.75%
(MHz)
C1
C2
R1 C1
C2
R1
(pF) (pF)
() (pF) (pF)
()
20
1
0 270 100,000 330 270 100,000 560
21-22 1 0 270 100,000 390 270 100,000 620
23-24 1 0 270 100,000 510 270 100,000 750
25-26 1 0 270 100,000 560 270 100,000 820
27-28 1 0 270 100,000 620 270 100,000 1,000
29-30 1 0 270 100,000 750 270 100,000 1,100
31-32 1 0 270 100,000 820 270 100,000 1,200
33-34 1 0 270 100,000 910 270 100,000 1,300
35-36 1 0 270 100,000 1,000 270 100,000 1,500
37-38 1 0 270 100,000 1,200 270 100,000 1,600
Please contact factory for loop filter values if desired spread settings are not listed.
BW = ± 1.00%
C1
C2
R1
(pF) (pF)
()
270 100,000 750
270 100,000 866(1%)
270 10,000 1,000
270 12,000 1,200
270 6,800 1,200
270 3,900 1,200
270 12,000 2,200
270 10,000 2,200
270 5,600 2,200
270 3,300 2,200
BW = ± 1.25%
C1
C2
R1
(pF) (pF)
()
560 100,000 910
560 100,000 1,100
680 6,800
1,200
470 4,700
1,200
330 3,300
1,200
330 3,300
1,500
680 6,800
2,200
390 3,900
2,200
270 2,700
2,200
270 2,700
2,700
Low-Cost Notebook EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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