SM8760CA Spread Spectrum Clock Generator OVERVIEW The SM8760CA is a compact clock generator IC with 4-times multiplication clock signal output that has a spread spectrum (SS) function to reduce undesirable EMI radiation. The SM8760CA has built-in crystal oscillator circuit, PLL, and loop filter. It accepts an input clock signal, generated using an external crystal or direct external clock input, and outputs 1 SS-modulated 4-times multiplication clock signal and 1 unmodulated reference signal. In addition, the SM8760CA features control pins to select SS modulation function ON/OFF and power-down modes. FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ PINOUT Spread spectrum clock output to reduce EMI Modulation rate: Center spread: ± 1.0% Input frequency • Using crystal element connection: 12.75MHz (fundamental frequency) • Using external input clock: 12.75MHz Multiplication: 4-time multiplication Operating supply voltage: 3.3 ± 0.3V Low jitter: 350ps typ (Cycle-to-Cycle) Functions: Power-down function, SS modulation ON/OFF Mode control pins: Pull-up resistors built-in Package: 8-pin VSOP (Top view) XT XTN PDN ENS 1 8 4 5 VDD CLKOUT VSS REFOUT APPLICATIONS ■ ■ ■ ■ ■ Printer (laser/inkjet) Photocopiers, scanners LCD/PDP displays Projectors Miscellaneous electronic equipment PACKAGE DIMENSIONS (Unit: mm) 0 to 10 ° 0.5 ± 0.2 8-pin VSOP 6.4 ± 0.3 SM8760CAV + 0.1 0.05 0.15 − 0.575TYP 3.1 ± 0.3 1.15 ± 0.05 Package 0.65 0.10 0.1 ± 0.05 Device 4.4 ± 0.2 ORDERING INFORMATION 0.22 ± 0.1 0.12 M SEIKO NPC CORPORATION —1 SM8760CA BLOCK DIAGRAM VDD VSS REFOUT XT X'tal OSC XTN R Counter Phase Detector & Charge Pump LPF N Counter VCO Post Divider CLKOUT (PLL) Mode, R/N Counter setting, Divider setting, etc. SS Control SSC Control Control Logic ENS PDN PIN DESCRIPTION Number Name I/O Function 1 XT I Crystal oscillator element connection or external clock input 2 XTN O Crystal oscillator element connection 3 PDN I Power-down control (with built-in pull-up resistor) 4 ENS I SS modulation function ON/OFF (with built-in pull-up resistor) 5 REFOUT O Reference clock output 6 VSS GND 7 CLKOUT O SS clock output 8 VDD PWR Supply voltage Ground SEIKO NPC CORPORATION —2 SM8760CA 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 150 mW TSTG −55 to +125 °C Output voltage range Power dissipation Storage temperature range Recommended Operating Conditions VSS = 0V unless otherwise noted. Rating Parameter Symbol Supply voltage range VDD Output load capacitance CL Master clock frequency fXTAL Operating temperature range Condition Unit min typ max +3.0 – +3.6 V CLKOUT, REFOUT output pins – – 15 pF Crystal oscillator element connection – 12.75 – External clock input – 12.75 – –20 – +80 TOPR MHz °C ELECTRICAL CHARACTERISTICS DC Characteristics VDD = 3.3 ± 0.3V, VSS = 0V, Ta = −20 to +80°C, fXTAL = 12.75MHz unless otherwise noted. Rating Parameter Current consumption Symbol max – 9 14 0.85VDD – – – – 0.15VDD 0.80VDD – – – – 0.20VDD VIN = VDD, built-in pull-up resistor – – 1 IIL1 VIN = 0V, built-in pull-up resistor –100 – – IIH2 VIN = VDD – – 40 VIN = 0V –40 – – VDD – 0.4 – – – – 0.4 IDD VDD PDN, ENS VIL1 XT VIL2 IIH1 PDN, ENS XT IIL2 Output voltage Unit typ VIH2 Input current Condition min VIH1 Input voltage Pins VOH VOL All outputs excluding XTN pin VDD = 3.3V, Ta = 25°C, crystal oscillator element connection, all outputs unloaded VDD = 3.3V VDD = 3.3V IOH = −2mA IOL = 2mA mA V µA V SEIKO NPC CORPORATION —3 SM8760CA AC Characteristics VDD = 3.3 ± 0.3V, VSS = 0V, Ta = −20 to +80°C unless otherwise noted. Rating Parameter Symbol Clock frequency Pins Condition Unit min typ max Crystal connection – 12.75 – External clock input*1 – 12.75 – fin XT Output clock rise time*2 tr CLKOUT, REFOUT CL = 15pF, VOL = 0.2VDD to VOH = 0.8VDD transition time – 2.0 – ns Output clock fall time*2 tf CLKOUT, REFOUT CL = 15pF, VOH = 0.8VDD to VOL = 0.2VDD transition time – 2.0 – ns 1-sigma jitter, Ta = 25°C, CL = 15pF, VO = 0.5VDD – 25 – Peak-to-peak jitter, Ta = 25°C, CL = 15pF, VO = 0.5VDD – 180 – CLKOUT Cycle-to-cycle jitter, Ta = 25°C, CL = 15pF, VO = 0.5VDD – 350 – Ta = 25°C, CL = 15pF, VO = 0.5VDD 45 50 55 % – 1 5 ms REFOUT Output clock jitter*2 tjitter Output clock duty cycle*2 Dt CLKOUT, REFOUT Power-up time*2,*3 tp CLKOUT, REFOUT 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 SEIKO NPC CORPORATION —4 SM8760CA FUNCTIONAL DESCRIPTION Master Clock The SM8760CA master clock can be generated by the crystal oscillator formed by connecting a crystal (fundamental mode) between XT (pin 1) and XTN (pin 2) 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 SM8760CA to breakdown. C1 External Clock XT (Pin1) XT (Pin1) Internal Circuits Oscillator Internal Circuits Oscillator Open XTN (Pin2) XTN (Pin2) C2 C1, C2 = 5 to 33pF Figure 2. Crystal element connection Figure 3. External clock input Function Controls The SM8760CA power-down and SS modulation ON/OFF functions are controlled using the PDN and ENS input pins as shown in Table 1. The power-down function is controlled using the PDN input pin. When PDN (pin 3) is “H”, normal operating mode is selected. When PDN is “L”, power-down mode is selected. In power-down mode, the CLKOUT and REFOUT output pins are in a high impedance state. The SS modulation function is controlled using the ENS input pin. When ENS (pin 4) is “H”, the SS modulation function is ON, and an SS-modulated clock is output on the CLKOUT pin. When ON, the modulation mode and amplitude is a fixed center spread modulation ± 1.0%. When ENS is “L”, the SS modulation function is OFF. Table 1. Function summary PDN (Pin 3) ENS (Pin 4) H H H L L H L L Power Down Output (Pin 5, Pin 7) OFF Clock out ON Hi-Z SS ON/OFF SS Mode SS Modulation [%] ON Center spread ± 1.0 OFF − 0.0 − − − Note. “H” signal represents VDD level, and “L” represents VSS level. SEIKO NPC CORPORATION —5 SM8760CA Typical Connection Circuit A typical connection circuit diagram is shown in Figure 4. 1) The SM8760CA 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) R201 and R202 are impedance matching resistor for board pattern. 4) 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 SM8760CA. C202 is a 33µF (approximately) electrolytic capacitor. C101 GND C102 Application Load GND R201 0 to 22Ω X'tal 12.75MHz GND XT XTN CLKOUT PDN VSS ENS REFOUT C201 0.1µF + PDN ENS VDD VDD C202 33µF IC1 SM8760CAV GND Application Load R202 0 to 22Ω GND Figure 4. Typical connection circuit Note. This is a sample connection diagram only, and its use is not a guarantee of SM8760CA device characteristics. SEIKO NPC CORPORATION —6 SM8760CA CLKOUT Output Spectrum Sample A sample SM8760CA CLKOUT output spectrum is shown in Figure 5. MKR:51.0MHz 9.21dBm RL:10.0dBm 10dB/AT30dB CNF:51MHz SPF:2.6MHz W:A ST 3s D:PK RB3kHz VB1kHz (a) ENS = "L", SS OFF MKR:50.709MHz − 9.19dBm W:A RL:10.0dBm 10dB/AT30dB ST 3s D:PK CNF:51MHz SPF:2.6MHz RB3kHz VB1kHz (b) ENS = "H", SS ± 1.0% Figure 5. Output spectrum sample Note. These spectrum diagrams were obtained using the NPC evaluation board. These spectrum diagrams are not guaranteed SM8760CA device characteristics. SEIKO NPC CORPORATION —7 SM8760CA 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 SEIKO NPC CORPORATION (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. SEIKO NPC CORPORATION 15-6, Nihombashi-kabutocho, Chuo-ku, Tokyo 103-0026, Japan Telephone: +81-3-6667-6601 Facsimile: +81-3-6667-6611 http://www.npc.co.jp/ Email: [email protected] NC0401BE 2006.04 SEIKO NPC CORPORATION —8