Rev 0; 11/07 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels The DS1181L is a spread-spectrum clock modulator IC that reduces EMI in high clock-frequency-based, digital electronic equipment. Using an integrated phase-locked loop (PLL), the DS1181L accepts an input clock signal in the range of 20MHz to 134MHz and delivers a spread-spectrum modulated output clock signal. The PLL modulates, or dithers, the output clock about the center input frequency at a pin-selectable magnitude, allowing direct EMI control and optimization. In addition, through an enable pin the dithering can be enabled or disabled for easy comparison of system performance during EMI testing. This same input pin also allows the DS1181L output to be three-stated. By dithering the system clock, all the address, data, and timing signals generated from this signal are also dithered so that the measured EMI at the fundamental and harmonic frequencies is greatly reduced. This is accomplished without changing clock rise/fall times or adding the space, weight, design time, and cost associated with mechanical shielding. The DS1181L is provided in an 8-pin TSSOP package and operates over a full automotive temperature range of -40°C to +125°C. Features ♦ Modulates a 20MHz to 134MHz Clock with Center Spread-Spectrum Dithering ♦ Selectable Spread-Spectrum Modulation Magnitudes of: ±0.5% ±1.0% ±1.5% ±2.0% ♦ Low 75ps Cycle-to-Cycle Jitter ♦ Spread-Spectrum Disable Mode ♦ Pin Compatible with Alliance/PulseCore Semiconductor P2040 Series Devices ♦ Clock Output Disable ♦ Low Cost ♦ Low Power Consumption ♦ 3.3V Single Voltage Supply ♦ -40°C to +125°C Temperature Range ♦ Small 8-Pin TSSOP Package Applications LCD Panels for TVs, Desktop Monitors, and Notebook and Tablet PCs Automotive Telematics and Infotainment Printers Typical Operating Circuit appears at end of data sheet. Ordering Information PART TEMP RANGE PIN-PACKAGE DS1181LE+ -40°C to +125°C 8 TSSOP DS1181LE+T -40°C to +125°C 8 TSSOP +Denotes a lead-free package. T = Tape and reel. Pin Configuration Block Diagram VCC DS1181L CLKIN fIN = 20MHz TO 134MHz VCC PLL WITH CENTERDITHERED SPREADSPECTRUM SSO fSSO = 20MHz to 134MHz (DITHERED) ENABLE LOGIC CRSEL SMSEL1 SMSEL2 SSEN TOP VIEW + CLKIN 1 8 VCC SMSEL1 2 7 CRSEL SMSEL2 3 6 SSO 5 SSEN DS1181L GND 4 CONFIGURATION DECODE AND CONTROL GND TSSOP ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 DS1181L General Description DS1181L 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels ABSOLUTE MAXIMUM RATINGS Voltage Range on VCC Relative to GND .............-0.5V to +3.63V Voltage Range on Any Lead Relative to GND ................-0.5V to (VCC + 0.5V), not to exceed +3.63V Operating Temperature Range .........................-40°C to +125°C Storage Temperature Range .............................-55°C to +125°C Soldering Temperature...................See J-STD-020 Specification Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS (TA = -40°C to +125°C, unless otherwise noted.) PARAMETER Supply Voltage SYMBOL VCC CONDITIONS (Note 1) MIN 3.6 V V 0.2 x VCC V 0V < VIN < VCC ±1 μA SSO < 80MHz 15 80MHz SSO < 134MHz 7 VIH Input Logic 0 VIL -0.3 SSO Load CL UNITS VCC + 0.3 Input Logic 1 IFLOAT MAX 3.0 0.8 x VCC Input Logic Float (SSEN, CRSEL) TYP pF CLKIN Frequency f IN 20 134 MHz CLKIN Duty Cycle f INDC 40 60 % MAX UNITS 18 mA DC ELECTRICAL CHARACTERISTICS (VCC = +3.0V to +3.6V, TA = -40°C to +125°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP Supply Current ICC CL = 7pF, f IN = 134MHz SMSEL1/SMSEL2/CLKIN Input Leakage I IL:1 0V < VIN < VCC -1 +1 μA CRSEL/SSEN Input Leakage IIL:2 0V < VIN < VCC -100 +100 μA Output Leakage (SSO) I OZ SSEN = float -1 +1 μA Low-Level Output Voltage (SSO) VOL I OL = 4mA 0.4 V High-Level Output Voltage (SSO) VOH I OH = -4mA 2.4 V AC ELECTRICAL CHARACTERISTICS (VCC = +3.0V to +3.6V, TA = -40°C to +125°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS TYP UNITS 60 % SSO Rise Time tR CL = 7pF 1 ns SSO Fall Time tF CL = 7pF 1 ns Peak Cycle-to-Cycle Jitter tJ TA = -40°C to +85°C, 10,000 cycles 75 ps t POR 40 MAX f SSODC Power-Up Time Measured at VCC/2 MIN SSO Duty Cycle (Note 2) Note 1: All voltages referenced to ground. Currents into the IC are positive and out of the IC are negative. Note 2: Time between power applied to device and stable output. 2 _______________________________________________________________________________________ 50 ms 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels SUPPLY CURRENT vs. SUPPLY VOLTAGE CLKIN = 134MHz 10 ICC (mA) CLKIN = 20MHz 4 CLKIN = 20MHz 6 CL = 7pF CL = 7pF 0 0 0 3.1 3.2 3.3 3.4 3.5 6 2 2 CL = 7pF 3.6 -40 10 60 20 110 40 60 80 100 120 TEMPERATURE (°C) FREQUENCY (MHz) DUTY CYCLE vs. SUPPLY VOLTAGE DUTY CYCLE vs. TEMPERATURE SPECTRUM ATTENUATION vs. FREQUENCY AT DIFFERENT DITHER AMPLITUDES 60 DS1181L toc04 CLKIN = 72MHz 56 52 50 48 54 52 50 48 46 46 44 44 42 42 40 CLKIN = 72MHz 56 DUTY CYCLE (%) 54 58 fOUT = 72MHz 0.5% ±1% ±1.5% ±2% 10dB 13dB 15dB 17dB ATTENUATION (dB) 60 DS1181L toc06 VCC (V) DS1181L toc05 3.0 VCC = 3.0V 4 4 2 DUTY CYCLE (%) VCC = 3.6V 8 8 ICC (mA) ICC (mA) 8 58 10 CLKIN = 66MHz CLKIN = 66MHz 6 DS1181L toc03 10 12 DS1181L toc02 CLKIN = 134MHz SUPPLY CURRENT vs. FREQUENCY SUPPLY CURRENT vs. TEMPERATURE 12 DS1181L toc01 12 RBW = 120KHz CENTER DITHER 40 3.0 3.1 3.2 3.3 VCC (V) 3.4 3.5 3.6 -40 10 60 TEMPERATURE (°C) 110 FREQUENCY (MHz) _______________________________________________________________________________________ 3 DS1181L Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels DS1181L Pin Description PIN NAME 1 CLKIN 2 SMSEL1 FUNCTION Clock Input. 20MHz to 134MHz clock input (fIN). Spread-Spectrum Magnitude Select Inputs. These digital inputs select the desired spread-spectrum magnitude as shown in the table below. SMSEL2 SMSEL1 MAGNITUDE SELECTED (%) 0 0 ±2.0 0 1 1 0 ±1.5 ±1.0 1 1 ±0.5 3 SMSEL2 4 GND Ground 5 SSEN Spread-Spectrum Enable. Three-level input to enable/disable spread-spectrum and to three-state the output. 0 = Power-up/spread-spectrum enabled. Float = SSO three-stated. 1 = Power-up/spread-spectrum disabled (not a bypass mode). 6 SSO Spread-Spectrum Clock Output. Outputs a center-dithered spread-spectrum version of the clock input at CLKIN. Clock Range and Dither Rate Select. Three-level input that determines the dither rate. See the Detailed Description section for details. 7 CRSEL 8 VCC CRSEL CLKIN RANGE (MHz) 0 66 to 134 Float 33 to 80 1 20 to 38 DITHER RATE f IN/832 Supply Voltage Detailed Description The DS1181L modulates an input clock to generate a center-dithered spread-spectrum output. A 20MHz to 134MHz clock is applied to the CLKIN pin. An internal PLL dithers the output clock about its center frequency at a user-selectable magnitude. Spread-Spectrum Dither Magnitude The DS1181L can generate dither magnitudes up to ±2%. The desired magnitude is selected using input pins SMSEL1 and SMSEL2 as shown in Table 1. Spread-Spectrum Dither Rate The output spread-spectrum dither rate is fixed at fIN/832. Table 2. Dither Rate CRSEL CLKIN RANGE (MHz) 0 66 to 134 Float 33 to 80 1 20 to 38 Table 1. Dither Magnitude 4 SMSEL2 SMSEL1 MAGNITUDE SELECTED (%) 0 0 ±2.0 0 1 ±1.5 1 0 ±1.0 1 1 ±0.5 _______________________________________________________________________________________ DITHER RATE f IN/832 20MHz to 134MHz Spread-Spectrum Clock Modulator for LCD Panels Power-Supply Decoupling To achieve best results, it is highly recommended that a decoupling capacitor is used on the IC power-supply pins. Typical values of decoupling capacitors are 0.01µF and 0.1µF. Use a high-quality, ceramic, surface-mount capacitor, and mount it as close as possible to the VCC and GND pins of the IC to minimize lead inductance. IF SSEN = 1 fIN + (0.5%, 1.0%, 1.5%, OR 2.0% OF fIN) DITHER AMOUNT (±0.5%, ±1.0%, ±1.5%, OR ±2.0%) fIN fIN - (0.5%, 1.0%, 1.5%, OR 2.0% OF fIN) 1 fSSO DITHER CYCLE RATE TIME CLKIN RANGE (MHz) 20 TO 134 DITHER RATE fIN/832 Figure 1. DS1181L Spread-Spectrum Frequency Modulation Typical Operating Circuit VCC fIN = 20MHz TO 134MHz VCC CLKIN DECOUPLING CAPACITOR CRSEL SMSEL1 DS1181L SSO fSSO SMSEL2 GND SSEN DITHERED NOTE: IN THE ABOVE CONFIGURATION WITH SMSEL1, SMSEL2, AND SSEN CONNECTED TO GND AS WELL AS CRSEL CONNECTED TO VCC, THE DEVICE IS CONFIGURED WITH A SPREAD-SPECTRUM MAGNITUDE OF ±2.0%, AND ALLOWS A CLKIN BETWEEN 20MHz and 38MHz. Package Information (For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.) PACKAGE TYPE DOCUMENT NO. 8 TSSOP 56-G2021-000 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. DS1181L Application Information Spread-Spectrum Enable On power-up, the output clock (SSO) remains three-stated until the internal PLL reaches a stable frequency. The SSEN input can be used to disable the spread-spectrum modulation and to three-state the SSO output. If the SSEN pin is pulled high, the spread-spectrum modulation is turned off, but the device still uses the internal PLL to generate the clock signal at SSO. If the SSEN pin is floated, the output is three-stated.