ASM3P2775A Peak EMI Reducing Solution
Features
• Generates an EMI optimized clock signal at the output. • Integrated loop filter components. • Operates with a 3.3V Supply. • Operating current less than 4mA. • CMOS design. • Input frequency range: 13MHz to 30MHz • Generates a 1X low EMI spread spectrum clock of the input frequency. • Frequency deviation: ±1.8% (Typ) @14.7MHz Input Frequency. • Available in 6L-TSOP (6L-TSOT-23) package. The ASM3P2775A uses the most efficient and optimized modulation profile approved by the FCC and is implemented by using a proprietary all digital method. The ASM3P2775A 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 result 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 ASM3P2775A is targeted towards all portable devices with very low power requirements like MP3 players and digital still cameras.
Product Description
The ASM3P2775A is a versatile spread spectrum frequency modulator designed specifically for a wide range of clock frequencies. The ASM3P2775A reduces electromagnetic interference (EMI) at the clock source, allowing system wide reduction of EMI of all clock dependent signals. The ASM3P2775A allows significant system cost savings by reducing the number of circuit board layers, ferrite beads and shielding that are traditionally required to pass EMI regulations.
Key Specifications
Description Supply voltage Cycle-to-Cycle Jitter Output Duty Cycle Modulation Rate Equation Frequency Deviation Specification VDD = 3.3V ± 0.3V ±200pS (typ) 45/55% (worst case) FIN/640 ±1.8% (Typ) @ 14.7MHz
Block Diagram
VDD PD
Modulation XIN/CLKIN XOUT Crystal Oscillator Frequency Divider Feedback Divider
PLL
Phase Detector
Loop Filter
VCO
Output Divider ModOUT
VSS
©2010 SCILLC. All rights reserved. JANUARY 2010 – Rev. 1
Publication Order Number: ASM3P2775/D
ASM3P2775A
Pin Configuration (6L-TSOP Package)
PD 1 XOUT
2
6
VSS ModOUT VDD
ASM3P2775A
5 4
XIN / CLKIN 3
Pin Description Pin#
1 2 3 4 5 6
Pin Name
PD XOUT XIN / CLKIN VDD ModOUT VSS
Type
I O I P O P
Description
Power-down control pin. Pull low to enable power-down mode. Connect to VDD if not used. Crystal connection. If using an external reference, this pin must be left unconnected. Crystal connection or external reference frequency input. This pin has dual functions. It can be connected either to an external crystal or an external reference clock. Power supply for the entire chip. Spread spectrum clock output. Ground connection.
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ASM3P2775A
Modulation Profile
Specifications Description
Frequency Range Modulation Equation Frequency Deviation
Specification
13MHz < CLKIN < 30MHz FIN/640 ±1.8% (Typ) @ 14.7MHz
Absolute Maximum Ratings Symbol
VDD, VIN TSTG TA Ts TJ TDV Storage temperature Operating temperature
Parameter
Rating
-0.5 to +4.6 -65 to +125 -40 to +85 260 150 2
Unit
V ° C ° 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.
Operating Conditions Parameter
VDD TA CL CIN Supply Voltage Operating Temperature (Ambient Temperature) Load Capacitance Input Capacitance
Description
Min
3.0 0
Max
3.6 +70 15 7
Unit
V ° C pF pF
Rev. 1 | Page 3 of 8 | www.onsemi.com
ASM3P2775A
DC Electrical Characteristics Symbol
VIL VIH IIL IIH IXOL IXOH VOL VOH IDD ICC VDD tON ZOUT Input low voltage Input high voltage Input low current Input high current XOUT output low current (@ 0.4V, VDD = 3.3V) XOUT output high current (@ 2.5V, VDD = 3.3V) Output low voltage (VDD = 3.3 V, IOL = 8mA) Output high voltage (VDD = 3.3 V, IOH = 8mA) Static supply current Operating voltage Power-up time (first locked cycle after power-up) Output impedance
1 1
Parameter
Min
VSS-0.3 2.0
Typ
Max
0.8 VDD+0.3 -35 35
Unit
V V µA µA mA mA
3 3 0.4 2.5 10 3.5 3.0 3.3 45 3.6 5
V V uA mA V mS
Dynamic supply current (3.3V, 16MHz and no load)
Notes: 1. XIN / CLKIN pin and PD pin are pulled low. 2. VDD and XIN / CLKIN input are stable, PD pin is made high from low.
AC Electrical Characteristics Symbol
CLKIN ModOUT fd tLH tHL
1 1
Parameter
Input frequency Output frequency Frequency Deviation Input Frequency = 13MHz Input Frequency = 30MHz
Min
13 13
Typ
Max
30 30
Unit
MHz MHz %
±1.85% ±1.45% 0.5 0.3 1.1 0.8 ±200 45 50 1.3 1.0 ±300 55
Output rise time (measured from 0.8 to 2.0V) Output fall time (measured at 2.0V to 0.8V) Jitter (cycle-to-cycle) Output duty cycle
nS nS pS %
tJC tD
Note: 1. tLH and tHL are measured into a capacitive load of 15pF.
Rev. 1 | Page 4 of 8 | www.onsemi.com
ASM3P2775A
Typical Crystal Specifications
Fundamental AT cut parallel resonant crystal Nominal frequency Frequency tolerance Operating temperature range Storage temperature Load capacitance Shunt capacitance ESR 14.31818MHz ±50ppm or better at 25° C -25° to +85° C C -40° to +85° C C 18pF 7pF maximum 25 Ω
Note: CL is Load Capacitance and Rx is used to prevent oscillations at overtone frequency of the Fundamental frequency.
Typical Crystal Interface Circuit
R
Crystal XIN CL
Rx XOUT
CL
CL = 2*(CP – CS), Where CP = Load capacitance of crystal from crystal vendor datasheet. CS = Stray capacitance due to CIN, PCB, Trace, etc.
Rev. 1 | Page 5 of 8 | www.onsemi.com
ASM3P2775A
Typical Application Schematic
VDD C1 0.1µF
C2 2.2µF VDD XIN / CLKIN CL Y1 XOUT CL ASM3P2775A VDD ModOUT Rs ModOUT Clock
PD VSS
Note: Refer to Pin Description table for Functionality details.
Rev. 1 | Page 6 of 8 | www.onsemi.com
ASM3P2775A
Package Information 6L-TSOP Package
Dimensions Symbol Min
A A1 A2 b H D B e C L θ ….. 0.00 0.033 0.012
Inches Max
0.04 0.004 0.036 0.02
Millimeters Min Max
…… 0.00 0.84 0.30 0.127 BSC 2.90 BSC 1.60 BSC 0.950 BSC 2.80 BSC 0.30 0° 0.50 4° 1.00 0.10 0.90 0.50
0.005 BSC 0.114 BSC 0.06 BSC 0.0374 BSC 0.11 BSC 0.0118 0° 0.02 4°
Rev. 1 | Page 7 of 8 | www.onsemi.com
ASM3P2775A
Ordering Information Part Number
ASM3P2775AF-06OR
Marking
X4L
Package Type
6L-TSOP (6L-TSOT-23), TAPE & REEL, Pb Free
Temperature
0° to +70° C C
A “microdot” placed at the end of last row of marking or just below the last row toward the center of package indicates Pb-free.
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