ASM3P2183A
EMI Reduction IC
Features
FCC approved method of EMI attenuation.
Provides up to 15dB EMI reduction.
Generates a 1X low EMI spread spectrum clock of
the input frequency.
Input frequency range: 6MHz to 90MHz.
Internal loop filter minimizes external components
and board space.
Selectable spread options: Down and Center
Spread.
2 spread frequency deviation selections:
o
-1.25% or ± 0.42%
Low inherent cycle-to-cycle jitter.
Supply Voltage: 3.3 V ± 0.3V.
Low power CMOS design.
Supports notebook VGA and other LCD timing
controller applications.
Products are available for Industrial temperature
range.
Available in 8-pin SOIC and TSSOP Packages.
The ASM3P2183A reduces electromagnetic interference
(EMI) at the clock source, allowing system wide reduction
of EMI of down stream clock and data dependent signals.
The ASM3P2183A allows significant system cost savings
by reducing the number of circuit board layers ferrite
beads, shielding and other passive components that are
traditionally required to pass EMI regulations.
The ASM3P2183A uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all digital method.
The ASM3P2183A modulates the output of a single PLL
in order to “spread” the bandwidth of a synthesized clock,
and more importantly, decreases the peak amplitudes of
its harmonics. This results in significantly lower system
EMI compared to the typical narrow band signal produced
by oscillators and most frequency generators. Lowering
EMI by increasing a signal‟s bandwidth is called „spread
spectrum clock generation.‟
Applications
The ASM3P2183A is targeted towards EMI management
for memory and LVDS interfaces in mobile graphic
chipsets and high-speed digital applications such as PC
peripheral devices, consumer electronics, and embedded
controller systems.
Product Description
The ASM3P2183A is a versatile spread spectrum
frequency modulators designed specifically for a wide
range of input clock frequencies from 6MHz to 90MHz.
(Refer
to
Input Frequency and Modulation Rate Table).
The ASM3P2183A can generate an EMI reduced clock
from an OSC or a system generated clock. The
ASM3P2183A offers a Down Spread clock with a
percentage deviation of -1.25% and a Center Spread
clock with a percentage deviation of ± 0.42%.
©2010 SCILLC. All rights reserved.
JANUARY 2010 – Rev. 2
Publication Order Number:
ASM3P2183/D
ASM3P2183A
Block Diagram
FS0
FS1
SS%
V
DD
Modulation
XIN / CLKIN
Crystal
Oscillator
XOUT
Frequency
Divider
Feedback
Divider
PLL
Phase
Detector
Loop
Filter
VCO
Output
Divider
ModOUT
Pin Configuration
V
SS
XIN / CLKIN
1
XOUT
2
8
FS1
7
FS0
ASM3P2183A
V
SS
SS%
3
6
V
DD
ModOUT
4
5
Pin Description
Pin#
1
2
3
4
5
6
7
Pin Name
XIN / CLKIN
XOUT
V
SS
SS%
ModOUT
V
DD
FS0
Type
I
I
P
I
O
P
I
Description
Crystal connection or external frequency input. This pin has dual functions. It can
be connected to either an external crystal or an external reference clock.
Crystal connection. Input connection for an external crystal. If using an external
reference, this pin must be left unconnected.
Ground to entire chip.
Spread range select. Digital logic input used to select frequency deviation
(Refer to
Spread Deviation Selection Table).
This pin has an internal pull-up
resistor.
Spread spectrum low EMI output.
Power supply for the entire chip.
Frequency range select. Digital logic input used to select frequency range
(Refer to
Input Frequency and Modulation Rate Table).
This pin has an internal
pull-up resistor.
Frequency range select. Digital logic input used to select frequency range
(Refer to
Input Frequency and Modulation Rate Table).
This pin has an internal
pull-up resistor.
8
FS1
I
Rev. 2 | Page 2 of 8 | www.onsemi.com
ASM3P2183A
Input Frequency and Modulation Rate Table
FS1 (pin 8)
0
0
1
1
FS0 (pin 7)
0
1
0
1
Frequency Range
6MHz to 13MHz
12MHz to 25MHz
25MHz to 50MHz
50MHz to 90MHz
Spread Deviation Selection Table
SS% (pin 4)
0
1
Spread Deviation (%)
- 1.25
± 0.42
Absolute Maximum Ratings
Symbol
V
DD
, V
IN
T
STG
T
s
T
J
T
DV
Storage temperature
Parameter
Rating
-0.5 to +4.6
-65 to +125
260
150
2
Unit
V
°C
°C
°C
KV
Voltage on any pin with respect to Ground
Max. Soldering Temperature (10 sec)
Junction Temperature
Static Discharge Voltage
(As per JEDEC STD22- A114-B)
Note: These are stress ratings only and are not implied for functional use. Exposure to absolute maximum ratings for prolonged periods of time may affect
device reliability.
Recommended Operating Conditions
Symbol
T
A
VDD
Parameter
Operating Temperature
Core Voltage
Min
0
+3.0
Typ
+3.3
Max
+70
+3.6
Units
°C
V
Rev. 2 | Page 3 of 8 | www.onsemi.com
ASM3P2183A
DC Electrical Characteristics
Symbol
V
IL
V
IH
I
IL
I
IH
I
XOL
I
XOH
V
OL
V
OH
I
CC
I
DD
V
DD
t
ON
Z
OUT
Input low voltage
Input high voltage
Input low current
Input high current
XOUT Output low current
(@ 0.4V, V
DD
= 3.3V)
XOUT Output high current
(@ 2.5V, V
DD
= 3.3V)
Output low voltage (V
DD
= 3.3V, I
OL
= 20mA)
Output high voltage (V
DD
= 3.3V, I
OH
= 20mA)
Dynamic supply current
Normal mode (3.3V, 90MHz and 10pF loading)
Static supply current
Operating voltage
Power up time (first locked clock cycle after power up)
Clock out impedance
1
Parameter
Min
V
SS
– 0.3
2.0
-
-
-
-
-
2.5
-
-
3.0
-
-
Typ
-
-
-
-
3
3
-
-
28
7.0
3.3
0.18
50
Max
0.8
V
DD
+ 0.3
-35
35
-
-
0.4
-
-
-
3.6
-
-
Unit
V
V
µA
µA
mA
mA
V
V
mA
mA
V
mS
Ω
Note: 1. XIN /CLKIN pin is pulled low.
AC Electrical Characteristics
Symbol
f
IN
ModOUT
1
t
LH
1
t
HL
Parameter
Input frequency
Output frequency
Output rise time (measured at 0.8V to 2.0V)
Output fall time (measured at 2.0V to 0.8V)
Jitter (cycle to cycle)
Output duty cycle
Min
6
6
0.3
0.5
-
45
Typ
-
-
0.9
1.0
-
50
Max
90
90
1.1
1.2
200
55
Unit
MHz
MHz
nS
nS
pS
%
t
JC
T
D
Note: 1. t
LH
and t
HL
are measured with a capacitive load of 15pF at 27MHz.
Rev. 2 | Page 4 of 8 | www.onsemi.com
Microchip MCU
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