September 2004
ASM3P2180A
rev 1.0
Pin Diagram
CLKIN / X1
NC / X2
GND
1
2
3
4
8
7
6
5
NC
FS1
VDD
ASM3P2180A
CLKOUT
SS%
Modulation Width Selection
SS%
Output
0
1
FIN ≥ FOUT ≥ FIN – 1.25%
FIN ≥ FOUT ≥ FIN – 2.4%
Frequency Range Selection
FS1
0
Modulation Rate
6 ≤ FIN ≤10
1
18 ≤ FIN ≤ 30
Pin Description
Pin#
Pin Name
Type
Description
Crystal connection or external reference frequency input. This pin has
dual functions. It can be connected to either an external crystal or an
external reference clock.
1
CLKIN / X1
I
Crystal connection. Connection for an external crystal. If using an
external reference, this pin must be left unconnected.
2
3
NC / X2
GND
O
P
Ground to entire chip.
Modulation width selection. When spread spectrum feature is turned
on, this pin is used to select the amount of variation and peak EMI
reduction that is desired on the output signal. Internal pull-up resistor.
4
SS%
I
5
6
CLKOUT
VDD
O
P
Output modulated frequency. Copy of the un-modulated input clock.
Power supply for the entire chip (3.3V).
Frequency selection bit 1. This pin selects the frequency range of
operation. (Refer to the Frequency Range Selection Table). This pin
has an internal pull-up resistor.
7
8
FS1
NC
I
-
No connect.
Peak Reducing EMI Solution
2 of 7
Notice: The information in this document is subject to change without notice.
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
