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ASM3P2853AG-08SR

P1-P3P4-P6P7-P7
ASM3P2853A
Peak EMI Reducing Solution
©2010 SCILLC. All rights reserved. Publication Order Number:
FEBRUARY 2012 – Rev. 3 ASM3P2853/D
Features
• Generates an EMI optimized clock signal at output.
• Input frequency: 25MHz.
• Frequency outputs:
o USB Clock (48MHz unmodulated)
o 50MHz (modulated), ±1% centre spread
• Modulation rate: 39KHz.
• Spread Spectrum ON/OFF control
• Supply voltage range 2.5V ± 5%.
• Available in 8-Pin SOIC package.
Product Description
The ASM3P2853A is a versatile spread spectrum
frequency modulator. The ASM3P2853A reduces
electromagnetic interference (EMI) at the clock source.
The ASM3P2853A allows significant system cost savings
by reducing the number of circuit board layers and
shielding that are required to pass EMI regulations. The
ASM3P2853A modulates the output of PLL in order to
spread the bandwidth of a synthesized clock, thereby
decreasing 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 clock generators. Lowering EMI by increasing a
signal’s bandwidth is called spread spectrum clock
generation.
Applications
ASM3P2853A is targeted towards EMI management for
high speed digital applications such as PC peripheral
devices, consumer electronics and embedded controller
systems.
Block Diagram
V
SS
V
DD
Crystal
Oscillator
50MHz
Modulated
XIN
XOUT
USB Clock
(48MHz
Unmodulated)
PLL1
PLL2
PWDNB
SSONB
ASM3P2853A
Rev. 2 | Page 2 of 7 | www.onsemi.com
Pin Configuration
Pin Description
Pin#
Pin
Name
Type Description
1 XIN I
Connection to crystal or external reference frequency input. This pin has dual
functions. It can be connected either to an external crystal or an external
reference clock.
2 XOUT O
Connection to crystal. If using an external reference clock, this pin must be left
unconnected.
3 V
DD
P Power supply for the analog and digital blocks.
4 V
SS
P Ground to entire chip.
5 PWDNB I
Power-down control pin. Pull low to enable the power-down mode. Connect to
VDD, if not used.
6 SSONB I
Digital logic input used to enable spread spectrum function (Active LOW).
Spread spectrum is enabled when LOW, disabled when HIGH.
7
USB
Clock
O Clock output-1 (48MHz unmodulated).
8 50MHz O Clock output-2 (50MHz modulated).
50MHz
V
SS
XOUT
XIN
V
DD
8
7
6
5
1
2
3
4
ASM3P2853A
PWDNB
SSONB
USB Clock
ASM3P2853A
Rev. 2 | Page 3 of 7 | www.onsemi.com
Absolute Maximum Ratings
Symbol Parameter Rating Unit
VDD, V
IN
Voltage on any pin with respect to Ground -0.5 to +4.6 V
T
STG
Storage temperature -65 to +125 °C
T
s
Max. Soldering Temperature (10 sec) 260 °C
T
J
Junction Temperature 150 °C
T
DV
Static Discharge Voltage (As per JEDEC STD22- A114-B) 2 KV
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.
Operating Conditions
Parameter Symbol Condition / Description Min Typ Max Unit
Supply Voltage V
DD
2.5V ± 5% 2.375 2.5 2.625 V
Ambient Operating
Temperature Range
T
A
-40 - +85 °C
Crystal Resonator Frequency F
XIN
25 MHz
Output Driver Load Capacitance C
L
- - 15 pF
Crystal Specifications
Fundamental AT cut parallel resonant crystal
Nominal frequency 25MHz
Frequency tolerance ±50ppm or better at 25°C
Operating temperature range -25°C to +85°C
Storage temperature -40°C to +85°C
Load capacitance 18pF
Shunt capacitance 7pF maximum
ESR 25Ω
Note: C
Y
is Load Capacitance and Rx is used to prevent oscillations at overtone frequency of the Fundamental frequency.
Typical Crystal Interface Circuit
C
Y
= 2*(C
P
– C
S
),
Where C
P
= Load capacitance
of crystal from crystal vendor datasheet
C
S
= Stray capacitance due to C
IN,
PCB, Trace etc.
C
Y
Rx
C
Y
Crystal
R
XIN XOUT
P1-P3P4-P6P7-P7

ASM3P2853AG-08SR

Mfr. #:
Buy ASM3P2853AG-08SR
Manufacturer:
ON Semiconductor
Description:
Clock Generators & Support Products 2.5V CUSTOM CG
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
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