ASM3P2853A Peak EMI Reducing Solution 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. 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 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 ASM3P2853A is targeted towards EMI management for high speed digital applications such as PC peripheral devices, consumer electronics and embedded controller systems. Block Diagram VDD XIN XOUT Crystal Oscillator SSONB PWDNB PLL1 USB Clock (48MHz Unmodulated) PLL2 50MHz Modulated VSS (c)2010 SCILLC. All rights reserved. FEBRUARY 2012 - Rev. 3 Publication Order Number: ASM3P2853/D ASM3P2853A Pin Configuration XIN 1 XOUT 2 8 50MHz 7 USB Clock ASM3P2853A VDD 3 6 SSONB VSS 4 5 PWDNB Pin Description Pin# Pin Name Type 1 XIN I Description 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. Connection to crystal. If using an external reference clock, this pin must be left 2 XOUT O 3 VDD P Power supply for the analog and digital blocks. 4 VSS P Ground to entire chip. 5 PWDNB I 6 SSONB I 7 8 USB Clock 50MHz unconnected. Power-down control pin. Pull low to enable the power-down mode. Connect to VDD, if not used. Digital logic input used to enable spread spectrum function (Active LOW). Spread spectrum is enabled when LOW, disabled when HIGH. O Clock output-1 (48MHz unmodulated). O Clock output-2 (50MHz modulated). Rev. 2 | Page 2 of 7 | www.onsemi.com ASM3P2853A Absolute Maximum Ratings Symbol VDD, VIN TSTG Rating Unit Voltage on any pin with respect to Ground Parameter -0.5 to +4.6 V Storage temperature -65 to +125 C Ts Max. Soldering Temperature (10 sec) 260 C TJ TDV Junction Temperature Static Discharge Voltage (As per JEDEC STD22- A114-B) 150 2 C 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 Supply Voltage Ambient Operating Temperature Range Crystal Resonator Frequency Output Driver Load Capacitance Condition / Description VDD 2.5V 5% TA Min Typ Max 2.375 2.5 2.625 V -40 - +85 C FXIN 25 CL - - MHz 15 Crystal Specifications Fundamental AT cut parallel resonant crystal Nominal frequency 25MHz Frequency tolerance 50ppm or better at 25C Operating temperature range -25C to +85C Storage temperature -40C to +85C Load capacitance 18pF Shunt capacitance 7pF maximum ESR 25 Note: CY is Load Capacitance and Rx is used to prevent oscillations at overtone frequency of the Fundamental frequency. Typical Crystal Interface Circuit R Crystal XIN Rx XOUT CY CY CY = 2*(CP - CS), Where CP = Load capacitance of crystal from crystal vendor datasheet CS = Stray capacitance due to CIN, PCB, Trace etc. Rev. 2 | Page 3 of 7 | www.onsemi.com Unit pF ASM3P2853A DC Electrical Characteristics Parameter Symbol Conditions / Description Min Typ Max Unit IDD VDD = 2.5V, FXIN = 25MHz, CL = 15pF 7 13 20 mA IDDL VDD = 2.5V, XIN = 0, PWDNB = 0 - 12 - uA Overall Supply Current, Dynamic Supply Current, Static All input pins High-Level Input Voltage Low-Level Input Voltage High-Level Input Current Low-Level Input Current (pull-up) VIH VDD = 2.5V 1.7 - - V VIL VDD = 2.5V - - 0.7 V IIH - - 25 A IIL - - -25 A Clock Outputs High-Level Output Source Current Low-Level Output Sink Current High-Level Output Source Current Low-Level Output Sink Current Output Impedance IxOH VDD = 2.5V ,V(XIN) = 0, VO = 2V - -15 - mA IxOL VDD = V(XIN) = 2.5V, VO = 0.4V - 15 - mA IOH VO = 2V - 8 - mA IOL VO = 0.4V - 8 - mA - 42 - ZO Rev. 2 | Page 4 of 7 | www.onsemi.com ASM3P2853A AC Electrical Characteristics Parameter 1 Symbol Min Typ Max Unit - 2 - nS - 1.5 - nS tjc - 250 - pS tp - 175 - pS 45 50 55 % - - 5 mS Measured from 20% to 80% of the Rise Time tr 1 tf Fall Time Jitter (Cycle-to-Cycle) Jitter (Period) Conditions / Description signal level Measured from 80% to 20% of the signal level Ratio of pulse width (as measured from Clock Duty Cycle td rising edge to next falling edge at VDD/2) to one clock period Power-up time tON first locked cycle after power-up (With stable VDD and valid input clock) Note: 1. CL = 15 pF, Input clock frequency = 25MHz Typical Application Schematic using ASM3P2853A Device 25MHz fundamental Crystal 1 XIN 2 XOUT 3 VDD 50MHz 8 USB Clock 7 SSONB B VSS PWDNB ASM3P2853A 6 27pF +2.5V Modulated 50MHz output 27pF 4 0.1uF 5 Rev. 2 | Page 5 of 7 | www.onsemi.com Un-modulated 48MHz output ASM3P2853A Package Information 8-Pin SOIC package H E D A2 A C D e A1 L B Dimensions Symbol Inches Min Max Millimeters Min Max A1 0.004 0.010 0.10 0.25 A 0.053 0.069 1.35 1.75 A2 0.049 0.059 1.25 1.50 B 0.012 0.020 0.31 0.51 C 0.007 0.010 0.18 0.25 D 0.193 BSC 4.90 BSC E 0.154 BSC 3.91 BSC e 0.050 BSC 1.27 BSC H 0.236 BSC 6.00 BSC L 0.016 0.050 0 8 0.41 1.27 0 8 Coplanarity 4 mil Rev. 2 | Page 6 of 7 | www.onsemi.com ASM3P2853A Ordering Code Part number Marking ASM3P2853AG-08SR AEC Package Configuration 8-pin SOIC, TAPE & REEL, Green Temperature Range 0C to +70C 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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