A2181A-08TT Alliance Semiconductor, A2181A-08TT Datasheet - Page 2

• Manufacturer Part Number: A2181A-08TT
• Description: 3.3 V, 3 MHz to 78 MHz, general purpose EMI reduction IC
• Manufacturer: Alliance Semiconductor

October 2003
rev 1.0
Pin Configuration
Pin Description (P278XA)
Pin#
Input Frequency Selection Table
FS1
1
2
3
4
5
6
7
8
0
0
1
1
XIN/CLKIN
XOUT
FS1
LF
VSS
ModOUT
FS0
VDD
FS0
Pin Name
0
1
0
1
Input (MHz)
10 to 19
20 to 38
39 to 78
3 to 9
Type
O
P
I
I
I
I
I
I
Notice: The information in this document is subject to change without notice.
Connect to crystal or clock input.
Crystal output
Digital logic input used to select input frequency range (see the Input
Frequency Selection Table). This pin has an internal pull-up resistor.
External Loop Filter for the PLL. By changing the value of the CRC circuit,
the percentage spread can be adjusted accordingly. See the Loop Filter
Selection Table for detail value.
Ground Connection. Connect to system ground.
Spread Spectrum Clock Output.
Digital logic input used to select input frequency range (see the Input
Frequency Selection Table). This pin has an internal pull-up resistor.
Connect to +3.3 V
10 to 19
20 to 38
39 to 78
P2781X
3 to 9
Output Frequency Scaling (MHz)
General Purpose EMI Reduction IC
78 to 156
P2782X
20 to 38
40 to 76
6 to 18
Description
156 to 312
80 to 152
P2784X
12 to 36
40 to 76
Modulation Rate (KHz)
P2781/82/84
Fin / 1024
Fin / 128
Fin / 256
Fin / 512
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