SM8761 series Spread Spectrum Clock Generator OVERVIEW The SM8761 series are compact clock generator ICs that have a spread spectrum (SS) function to reduce undesirable EMI radiation. They have a built-in crystal oscillator circuit, PLL, and loop filter. They accept an input clock signal, generated using an external crystal or direct external clock input, and output an SS-modulated clock signal. In addition, versions are available for center spread and down spread modulation mode, and all have a mode control pin to select the SS modulation function. FEATURES ■ ■ ■ Spread spectrum clock output to reduce EMI Correspond to wide range of output frequency Low jitter ■ ■ ■ Operating supply voltage: 3.3 ± 0.3V Multiplication: 1-time multiplication Package: 8-pin SOP SM8761AA SM8761AB Spectrum modulation mode Down spread Center spread Spectrum modulation rate*1 – 1.0% to – 3.8% ± 0.75% to ± 2.25% Crystal element connection 20MHz to 40MHz 12MHz to 32MHz External input clock 20MHz to 108MHz 12MHz to 32MHz Input frequency Output frequency 20MHz to 108MHz 12MHz to 32MHz Multiplication 1-time multiplication 1-time multiplication 200ps (typ) @33MHz Jitter (Cycle-to-Cycle) 200ps (typ) @16MHz 120ps (typ) @75MHz *1. The modulation rate that can be selected varies with the input frequency. PINOUT PACKAGE DIMENSIONS (Top view) (Unit: mm) 0.15 −+ 0.1 8 XTN VDD 2 7 MSEL1 VSS 3 6 MSEL0 CLKOUT 4 5 TSTN 0.4 ± 0.2 1 4.4 ± 0.2 XT 6.2 ± 0.3 0.05 0.695typ 1.5 ± 0.1 0.05 ± 0.05 5.2 ± 0.3 1.27 0.10 0.4 ± 0.1 APPLICATIONS ■ ■ ■ ■ ■ Printer (laser/inkjet) Photocopiers, scanners LCD/PDP displays Projectors Miscellaneous electronic equipment 0 to 10° 0.12 M ORDERING INFORMATION Device Package SM8761AAS SM8761ABS 8-pin SOP NIPPON PRECISION CIRCUITS INC.—1 SM8761 series BLOCK DIAGRAM VDD XT X'tal OSC R Counter VSS Phase Detector & Charge Pump LPF N Counter VCO XTN Post Divider CLKOUT (PLL) SS Control Mode, R/N Counter setting, Divider setting, etc. SS Control Control Logic MSEL0 MSEL1 TSTN PIN DESCRIPTION Number Name I/O*1 1 XT I 2 VDD PWR Supply voltage 3 VSS GND Ground 4 CLKOUT O SS clock output 5 TSTN Ip Test (Tie HIGH or leave open circuit) 6 MSEL0 I SS modulation rate setting 7 MSEL1 I SS modulation rate setting 8 XTN O Crystal oscillator element connection Function Crystal oscillator element connection or external clock input *1. Built-in pull-up resistor NIPPON PRECISION CIRCUITS INC.—2 SM8761 series SPECIFICATIONS Absolute Maximum Ratings Parameter Symbol Rating Unit Supply voltage range VDD −0.3 to +6.5 V Input voltage range VIN −0.3 to VDD + 0.3 V VOUT −0.3 to VDD + 0.3 V PD 300 mW TSTG −55 to +125 °C Output voltage range Power dissipation Storage temperature range Recommended Operating Conditions SM8761AA VSS = 0V unless otherwise noted. Rating Parameter Symbol Supply voltage range VDD Output load capacitance CL Master clock frequency fIN Operating temperature range Condition Unit min typ max +3.0 – +3.6 V CLKOUT output pin – – 15 pF Crystal oscillator element connection 20 – 40 External clock input 20 – 108 –20 – +80 TOPR MHz °C SM8761AB VSS = 0V unless otherwise noted. Rating Parameter Symbol Supply voltage range VDD Output load capacitance CL Master clock frequency fIN Operating temperature range TOPR Condition Unit min typ max +3.0 – +3.6 V CLKOUT output pin – – 15 pF Crystal oscillator element connection 12 – 32 External clock input 12 – 32 –20 – +80 MHz °C NIPPON PRECISION CIRCUITS INC.—3 SM8761 series ELECTRICAL CHARACTERISTICS DC Characteristics SM8761AA VDD = 3.3 ± 0.3V, VSS = 0V, Ta = −20 to +80°C unless otherwise noted. Rating Parameter Current consumption Symbol Pins Condition VDD = 3.3V, Ta = 25°C, external input clock, fin = 33MHz, all outputs unloaded IDD VIH2 MSEL0, MSEL1 TSTN VIL2 VIH3 XT VIL3 IIH1 MSEL0, MSEL1 IIL1 Input current IIH2 TSTN IIL2 IIH3 XT IIL3 Output voltage VOH VOL max – 11 16 mA VDD = 3.3V, Ta = 25°C, external input clock, fin = 75MHz, all outputs unloaded – 16 24 0.85VDD – – 0.45VDD 0.50VDD 0.55VDD – – 0.15VDD 0.85VDD – – – – 0.15VDD 0.80VDD – – – – 0.20VDD VIN = VDD – – 1 VIN = 0V –1 – – VIN = VDD, built-in pull-up resistor – – 1 VIN = 0V, built-in pull-up resistor –100 – – VIN = VDD – – 40 VIN = 0V –40 – – VDD – 0.4 – – – – 0.4 VDD = 3.3V VIL1 Input voltage typ VDD VIH1 VIM1 Unit min CLKOUT VDD = 3.3V VDD = 3.3V IOH = −2mA IOL = 2mA V µA V NIPPON PRECISION CIRCUITS INC.—4 SM8761 series SM8761AB VDD = 3.3 ± 0.3V, VSS = 0V, Ta = −20 to +80°C unless otherwise noted. Rating Parameter Current consumption Symbol Pins Condition VDD = 3.3V, Ta = 25°C, external input clock, fin = 12MHz, all outputs unloaded IDD VIH2 MSEL0, MSEL1 TSTN VIL2 VIH3 XT VIL3 IIH1 MSEL0, MSEL1 IIL1 Input current IIH2 TSTN IIL2 IIH3 XT IIL3 Output voltage VOH VOL max – 5 8 mA VDD = 3.3V, Ta = 25°C, external input clock, fin = 24MHz, all outputs unloaded – 6 10 0.85VDD – – 0.45VDD 0.50VDD 0.55VDD – – 0.15VDD 0.85VDD – – – – 0.15VDD 0.80VDD – – – – 0.20VDD VIN = VDD – – 1 VIN = 0V –1 – – VIN = VDD, built-in pull-up resistor – – 1 VIN = 0V, built-in pull-up resistor –100 – – VIN = VDD – – 40 VIN = 0V –40 – – VDD – 0.4 – – – – 0.4 VDD = 3.3V VIL1 Input voltage typ VDD VIH1 VIM1 Unit min CLKOUT VDD = 3.3V VDD = 3.3V IOH = −2mA IOL = 2mA V µA V NIPPON PRECISION CIRCUITS INC.—5 SM8761 series AC Characteristics SM8761AA VDD = 3.3 ± 0.3V, VSS = 0V, Ta = −20 to +80°C unless otherwise noted. Parameter Symbol Pins Clock frequency fin XT Output clock rise time*2 tr Output clock fall time*2 Rating Condition Unit min typ max Crystal connection 20 – 40 External clock input*1 20 – 108 CLKOUT CL = 15pF, VOL = 0.2VDD to VOH = 0.8VDD transition time – 2.0 – ns tf CLKOUT CL = 15pF, VOH = 0.8VDD to VOL = 0.2VDD transition time – 2.0 – ns – 200 – CLKOUT Cycle-to-cycle jitter, Ta = 25°C, CL = 15pF, VO = 0.5VDD fin = 33MHz tjitter fin = 75MHz – 120 – Output clock duty cycle*2 Dt CLKOUT 45 50 55 % Power-up time*2,*3 tp CLKOUT – 1 5 ms Output clock jitter*2 Ta = 25°C, CL = 15pF, VO = 0.5VDD MHz ps *1. When using an external clock input, it is recommended that the clock on XT have 50% duty and VDD level signal amplitude. Note that the input signal voltage must not exceed the absolute maximum rating, otherwise it may cause the device to breakdown. *2. Measured using the circuit in Figure 1 on the NPC standard evaluation board. *3. The power-up time is the time from when the supply reaches 3.0V after the supply is turned ON until each output clock reaches its designated frequency to within ± 0.1%. SM8761AB VDD = 3.3 ± 0.3V, VSS = 0V, Ta = −20 to +80°C unless otherwise noted. Parameter Symbol Pins Clock frequency fin XT Output clock rise time*2 tr Output clock fall time*2 tf Output clock jitter*2 tjitter Rating Condition Unit min typ max Crystal connection 12 – 32 External clock input*1 12 – 32 CLKOUT CL = 15pF, VOL = 0.2VDD to VOH = 0.8VDD transition time – 2.0 – ns CLKOUT CL = 15pF, VOH = 0.8VDD to VOL = 0.2VDD transition time – 2.0 – ns fin = 12MHz – 450 – CLKOUT Cycle-to-cycle jitter, Ta = 25°C, CL = 15pF, VO = 0.5VDD fin = 16MHz – 200 – fin = 20MHz – 300 – fin = 27MHz – 180 – 45 50 55 % – 1 5 ms Output clock duty cycle*2 Dt CLKOUT Power-up time*2,*3 tp CLKOUT Ta = 25°C, CL = 15pF, VO = 0.5VDD MHz ps *1. When using an external clock input, it is recommended that the clock on XT have 50% duty and VDD level signal amplitude. Note that the input signal voltage must not exceed the absolute maximum rating, otherwise it may cause the device to breakdown. *2. Measured using the circuit in Figure 1 on the NPC standard evaluation board. *3. The power-up time is the time from when the supply reaches 3.0V after the supply is turned ON until each output clock reaches its designated frequency to within ± 0.1%. X'tal + + DUT Active Probe (HP1152A) Oscilloscope (Infinium HP54845A) Passive Probe (HP10435A) Frequency & Time Interval Analyzer (HP5371A) DUT: Device Under Testing Jitter Measurement System (ASA, M1) Figure 1. Measurement circuit NIPPON PRECISION CIRCUITS INC.—6 SM8761 series FUNCTIONAL DESCRIPTION Master Clock The SM8761 series master clock can be generated by the crystal oscillator formed by connecting a crystal between XT (pin 1) and XTN (pin 8) as shown in Figure 2. Alternatively, an external master clock can be input directly on XT (pin 1) as shown in Figure 3. If an external clock is input on XT, it is recommended that the clock have 50% duty and VDD level voltage amplitude. Note that the input clock amplitude voltage must not exceed the absolute maximum rating, otherwise it may cause the SM8761 series to breakdown. C1 XT (Pin1) Internal Circuits Oscillator XTN (Pin8) C2 C1, C2 = 5 to 33pF Figure 2. Crystal element connection External Clock XT (Pin1) Oscillator Internal Circuits Open XTN (Pin8) Figure 3. External clock input NIPPON PRECISION CIRCUITS INC.—7 SM8761 series Function Controls The SM8761 series power-down and SS modulation ON/OFF functions are controlled using the MSEL0 and MSEL1 input pins as shown in Table 1. SM8761AA MSEL1 (Pin 7) MSEL0 (Pin 6) L L L M Input/Output frequency range [MHz] SS mode SS modulation*1 [%] –2.3 –3.2 20 to 54 (Low range) H M L –1.9 M M –3.8 M H –2.5 H L H M H H 50 to 108 (High range) Down spread −2.8 L –1.9 Down spread –1.0 –1.2 *1. The modulation rates in the table above are reference values at 30MHz to 40MHz (Low range) and 70MHz to 80MHz (High range). The modulation rate varies with the input/output frequency. Note. Signal level “H” represents VDD level, “L” represents VSS level, and “M” represents 1/2VDD. SM8761AB MSEL1 (Pin 7) MSEL0 (Pin 6) L L L M L H M L M M M H H L H M H H Input/Output frequency range [MHz] SS mode SS modulation*1 [%] ± 1.25 12 to 18 (Low range) Center spread ± 0.75 ± 1.75 ± 2.25 (reserved)*2 ± 2.25 18 to 32 (High range) Center spread ± 1.25 ± 0.75 ± 1.75 *1. The modulation rates in the table above are reference values at 12MHz (Low range) and 24MHz (High range). The modulation rate varies with the input/output frequency. *2. If MSEL1 (pin 7) and MSEL0 (pin 6) are both simultaneously "M" level, then SM8761AB operation cannot be guaranteed. Note. Signal level “H” represents VDD level, “L” represents VSS level, and “M” represents 1/2VDD. NIPPON PRECISION CIRCUITS INC.—8 SM8761 series Typical Connection Circuit A typical connection circuit diagram is shown in Figure 4. 1) The SM8761 series oscillator circuit between XT and XTN has a built-in feedback resistor (approximately 250kΩ). 2) The oscillator circuit capacitances C101 and C102 connected to XTN and XT, to match the crystal load capacitor. 3) If using an external clock input on XT, then connections to XT and XTN should be as shown in figure 3. 4) R201 is impedance matching resistor for board pattern. 5) C201 and C202 are bypass capacitors inserted between the supply voltage lines. C201 is a 0.1µF (approximately) multi-layer ceramic capacitor connected directly alongside the SM8761 series. C202 is a 33µF (approximately) electrolytic capacitor. C102 C101 VSS VSS X'tal VDD + XT C202 33µF C201 0.1µF XTN VDD MSEL1 MSEL1 VSS MSEL0 MSEL0 CLKOUT VSS TSTN IC1 SM8761 Application Load R201 0 to 22Ω VSS Note. This is a sample connection diagram only, and its use is not a guarantee of SM8761 series device characteristics. Figure 4. Typical connection circuit MSEL1 and MSEL0 Connection Method MSEL1 and MSEL0 both support a 1/2VDD "M" level for 3-value ("H", "M", "L") DC voltage input control. Typical connection circuits for each input level shown in figure 5. "H" level is input by connection to VDD, and "L" level by connection to VSS. "M" level is input by connection to the center tap of two identical resistances in series between VDD and VSS. The recommended resistance is 4.7kΩ. VDD VDD R301 4.7kΩ XTN XTN MSEL1 MSEL1 MSEL1 MSEL0 MSEL0 XTN TSTN MSEL0 R302 4.7kΩ TSTN TSTN VSS VSS (a)“H” level (b)“M” level (c)“L” level Figure 5. MSEL1 and MSEL0 typical connections NIPPON PRECISION CIRCUITS INC.—9 SM8761 series CLKOUT Output Spectrum Sample (SM8761AA) A sample SM8761AA CLKOUT output spectrum is shown in Figure 6. MKR:33.200MHz 9.37dBm RL:10.0dBm 10dB/AT30dB CNF:33.2MHz SPF:3.3MHz W:A ST 3s D:PK RB3kHz VB1kHz (a) NPC test mode: SS OFF, fin = 33.2MHz MKR:32.434MHz −5.19dBm RL:10.0dBm 10dB/AT30dB CNF:33.2MHz SPF:3.3MHz W:A ST 3s D:PK RB3kHz VB1kHz (b) MSEL1 = "L"/ MSEL0 = “H”: down spread –2.8%, fin = 33.2MHz Figure 6. Output spectrum sample Note. The output spectrum sample in figure (a) is for NPC test mode with the SS function OFF. Note. These spectrum diagrams were obtained using the NPC evaluation board. These spectrum diagrams are not guaranteed SM8761 series device characteristics. NIPPON PRECISION CIRCUITS INC.—10 SM8761 series Please pay your attention to the following points at time of using the products shown in this document. The products shown in this document (hereinafter “Products”) are not intended to be used for the apparatus that exerts harmful influence on human lives due to the defects, failure or malfunction of the Products. Customers are requested to obtain prior written agreement for such use from NIPPON PRECISION CIRCUITS INC. (hereinafter “NPC”). Customers shall be solely responsible for, and indemnify and hold NPC free and harmless from, any and all claims, damages, losses, expenses or lawsuits, due to such use without such agreement. NPC reserves the right to change the specifications of the Products in order to improve the characteristic or reliability thereof. NPC makes no claim or warranty that the contents described in this document dose not infringe any intellectual property right or other similar right owned by third parties. Therefore, NPC shall not be responsible for such problems, even if the use is in accordance with the descriptions provided in this document. Any descriptions including applications, circuits, and the parameters of the Products in this document are for reference to use the Products, and shall not be guaranteed free from defect, inapplicability to the design for the mass-production products without further testing or modification. Customers are requested not to export or re-export, directly or indirectly, the Products to any country or any entity not in compliance with or in violation of the national export administration laws, treaties, orders and regulations. Customers are requested appropriately take steps to obtain required permissions or approvals from appropriate government agencies. NIPPON PRECISION CIRCUITS INC. 4-3, Fukuzumi 2-chome, Koto-ku, Tokyo 135-8430, Japan Telephone: +81-3-3642-6661 Facsimile: +81-3-3642-6698 http://www.npc.co.jp/ Email: [email protected] NC0408AE 2004.12 NIPPON PRECISION CIRCUITS INC.—11