November 2003 ASM3P2531A rev 1.0 dependent signals. It allows significant system cost Features FCC approved method of EMI attenuation. savings by reducing the number of circuit board layers Generates a low EMI spread spectrum of the and shielding traditionally required to pass EMI input clock frequency. regulations. Optimized for input frequency range between 35MHz – 55MHz. The ASM3P2531A modulates the output of a single PLL Internal loop filter minimizes external in order to spread the bandwidth of a synthesized clock, components and board space. thereby decreasing the peak amplitudes of its harmonics. Frequency Deviation: ±1.65%. This results in significantly lower system EMI compared Low inherent cycle-to-cycle jitter. to the typical narrow band signal produced by oscillators 3.3 V or 5 V operating voltage. and most clock generators. Lowering EMI by increasing CMOS/TTL compatible inputs and outputs. a signal’s bandwidth is called spread spectrum clock Ultra low power CMOS design: 5.50 mA @3.3 V. generation. Supports notebook VGA and other LCD timing controller applications. The ASM3P2531A uses the most efficient and optimized Available in 8-pin SOIC and TSSOP. modulation profile approved by the FCC and is implemented by using a proprietary all-digital method. Product Description The ASM3P2531A is a versatile spread spectrum Applications frequency modulator designed specifically for a wide The ASM3P2531A is targeted toward the notebook VGA range of clock frequencies. It reduces electromagnetic chip and other displays using an LVDS interface, PC interference (EMI) at the clock source allowing system- peripheral devices, and embedded systems wide reduction of EMI of downstream clock and data Block Diagram STOP VDD PLL Modulation CLKIN Crystal Oscillator Frequency Divider Feedback Divider Phase Detector Loop Filter VCO Output Divider MODOUT VSS Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 1 of 8 November 2003 ASM3P2531A rev 1.0 Pin Configuration CLKIN 1 8 NC VDD 2 7 NC VSS 3 6 NC ModOUT 4 5 STOP ASM3P2531A Spread Range Selection, VDD = 3.3 V CLKIN frequency Spreading range Modulation rate 35 MHz – 55 MHz ±1.65% (CLKIN/1280) KHz Pin Description Pin# Pin Name Type Description 1 CLKIN I External reference frequency input. 2 VDD P Power supply for the entire chip. 3 VSS P Ground to entire chip. 4 ModOUT O Spread spectrum clock output or reference output. Refer Standby Mode Selection. 5 STOP I Active LOW signal. When HIGH, enables ModOUT and when LOW, ModOUT would be LOW. 6 NC - No connect. 7 NC - No connect. 8 NC - No connect. Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 2 of 8 November 2003 ASM3P2531A rev 1.0 Schematic for a Typical Application Input clock 35MHz – 55MHz 1 ASM3P3531A CLKIN NC 8 2 VDD NC 7 3 VSS NC 6 STOP 5 VDD 0.1µF Ferrite Bead VDD 0Ω 4 ModOUT EMI reduced clock output 35MHz – 55MHz 0Ω Use either pull-up or pulldown resistors with 0Ω Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 3 of 8 November 2003 ASM3P2531A rev 1.0 Absolute Maximum Ratings Symbol VDD, VIN Parameter Voltage on any pin with respect to GND Rating -0.5 to +7.0 Unit V TSTG Storage temperature -65 to +125 °C TA Operating temperature 0 to +70 °C DC Electrical Characteristics Symbol Parameter Min Typ Max Unit V VIL Input low voltage GND - 0.3 0.8 VIH Input high voltage 2.0 VDD + 0.3 V IIL Input low current -35 µA IIH Input high current 35 µA VOL Output low voltage 0.4 V VDD = 3.3 V, IOL = 20 mA VDD = 5.0 V, IOL = 20 mA 2.5 V VDD = 5.0 V, IOL = 20 mA 4.5 V VOH Output high voltage IDD Static supply current standby mode Normal mode ICC Dynamic supply current 0.6 fIN-min fIN-typ mA fIN-max 3.3 V and 10 pF loading 3.2 7.0 mA 5.0 V and 10 pF loading 6.2 13.6 mA 5.5 V VDD Operating voltage tON Power-up time (first locked cycle after power up) ZOUT V VDD = 3.3 V, IOL = 20 mA 2.7 Clock output impedance 3.3 0.18 mS 50 Ω AC Electrical Characteristics Symbol fIN fOUT Parameter Input frequency Output rise time tHL 1 Output fall time Typ 35 Output frequency tLH 1 Min 35 Measured at 0.8 V to 2.0 V 0.7 Measured at 1.2 V to 3.75 V Measured at 2.0 V to 0.8 V tJC Jitter (cycle to cycle) Output duty cycle Unit 55 MHz 55 MHz 1.1 ns 0.75 0.6 Measured at 1.2 V to 3.75 V TD 0.9 Max 0.8 ns 1.0 0.75 45 Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 50 ns ns 360 ps 55 % 4 of 8 November 2003 ASM3P2531A rev 1.0 Package Information 8-Pin SOIC Symbol Dimensions in inches Dimensions in millimeters Min Max Min Max A 0.053 0.069 1.35 1.75 A1 0.004 0.010 0.10 0.25 B 0.013 0.022 0.33 0.53 C 0.007 0.012 0.18 0.27 D 0.188 0.197 4.78 5.00 E 0.150 0.158 3.80 4.01 H 0.228 0.244 5.80 6.20 e 0.050 BSC 1.27 BSC L 0.016 0.035 0.40 0.89 θ 0° 8° 0° 8° Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 5 of 8 November 2003 ASM3P2531A rev 1.0 Package Information 8-Pin TSSOP Symbol Dimensions in inches Dimensions in millimeters Min Max Min Max A - 0.043 - 1.10 A1 0.002 0.006 0.05 0.15 A2 0.033 0.037 0.85 0.95 B 0.008 0.012 0.19 0.30 C 0.004 0.008 0.09 0.20 D 0.114 0.122 2.90 3.10 H E 0.252 BSC 0.169 e 6.40 BSC 0.177 4.30 0.026 BSC 4.50 0.65 BSC L 0.020 0.028 0.50 0.70 θ 0° 8° 0° 8° Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 6 of 8 November 2003 ASM3P2531A rev 1.0 Ordering Information Ordering Code Package Type Operating Range ASM3P2531A-08ST 8-pin 150mil SOIC -TUBE Commercial ASM3P2531A-08SR 8-pin 150-mil SOIC -TAPE & REEL Commercial ASM3I2531A-08ST 8-pin 150mil SOIC -TUBE Industrial ASM3I2531A-08SR 8-pin 150-mil SOIC -TAPE & REEL Industrial ASM3P2531A-08TT 8-pin 4.4mm TSSOP -TUBE Commercial ASM3P2531A-08TR 8-pin 4.4mm TSSOP -TAPE & REEL Commercial ASM3I2531A-08TT 8-pin 4.4mm TSSOP -TUBE Industrial ASM3I2531A-08TR 8-pin 4.4mm TSSOP - TAPE & REEL Industrial Ordering Information A S M 3 P 2 5 3 1 A - 0 8 T R OR - SOT23/T/R TT – TSSOP, TUBE TR - TSSOP, T/R VT – TVSOP, TUBE VR – TVSOP, T/R ST – SOIC, TUBE SR - SOIC, T/R QR – QFN, T/R QT - QFN, TUBE BT - BGA, TUBE BR – BGA, T/R PIN COUNT PART NUMBER X = Automotive I = Industrial 1 – reserved 2 - Non PLL based 3 – EMI Reduction 4 – DDR support products 5 – STD Zero Delay Buffer P or n/c = Commercial 6 – power management 7 – power management 8 – power management 9 – Hi performance 0 - reserved Alliance Semiconductor Mixed Signal Product Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 7 of 8 November 2003 ASM3P2531A rev 1.0 Alliance Semiconductor Corporation 2595, Augustine Drive, Santa Clara, CA 95054 Tel# 408-855-4900 Fax: 408-855-4999 www.alsc.com Copyright © Alliance Semiconductor All Rights Reserved Preliminary Information Part Number: ASM3P2531A Document Version: v1.0 © Copyright 2003 Alliance Semiconductor Corporation. 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Alliance does not authorize its products for use as critical components in life-supporting systems where a malfunction or failure may reasonably be expected to result in significant injury to the user, and the inclusion of Alliance products in such life-supporting systems implies that the manufacturer assumes all risk of such use and agrees to indemnify Alliance against all claims arising from such use. Low Frequency EMI Reduction Notice: The information in this document is subject to change without notice. 8 of 8