DS1090 Low-Frequency, Spread-Spectrum EconOscillator General Description The DS1090 is a low-cost, dithered oscillator intended to be used as an external clock for switched-mode power supplies and other low-frequency applications. The dithering or sweeping function reduces peak-radiated emissions from the power supply at its fundamental frequency, as well as harmonic frequencies. The device consists of a resistor-programmed master oscillator, factory-programmed clock prescaler, and a pin-programmed dither circuit. These features allow the DS1090 to be used in applications where a spread-spectrum clock is desired to reduce radiated emissions. A combination of factory-set prescalers and external resistor allows for output frequencies ranging from 125kHz to 8MHz. Both dither frequency and dither percentage are set using control pins. Features Low-Cost, Spread-Spectrum EconOscillatorTM Simple User Programming Output Frequency Programmable from 125kHz to 8MHz Dither Percentage Programmable from 0% to 8% Dither Rate Programmable (fMOSC/512, 1024, 2048, or 4096) 3.0V to 5.5V Single-Supply Operation CMOS/TTL-Compatible Output Operating Temperature Range: -40C to +85C Ordering Information OUTPUT FREQUENCY RANGE PRESCALER PINPACKAGE DS1090U-1+ 4MHz to 8MHz 1 8 SOP DS1090U-2+ 2MHz to 4MHz 2 8 SOP DS1090U-4+ 1MHz to 2MHz 4 8 SOP DS1090U-8+ 500kHz to 1MHz 8 8 SOP DS1090U-16+ 250kHz to 500kHz 16 8 SOP DS1090U-32+ 125kHz to 250kHz 32 8 SOP PART Applications Switched-Mode Power Supplies Servers Printers Embedded Microcontrollers Industrial Controls Typical Operating Circuit VOUT VIN Pin Configuration VCC VCC DC-DC STEP-DOWN CONVERTER JC0 45k TO 91k J0 GND TOP VIEW OUT DS1090 JC1 RSET Add "T" for Tape & Reel orders. J1 OUT 1 RSET 2 8 7 JC0 3 6 J1 GND 4 5 J0 VCC DS1090 SOP EconOscillator is a trademark of Maxim Integrated Products, Inc. 19-7500; Rev 3; 9/16 JC1 DS1090 Low-Frequency, Spread-Spectrum EconOscillator Absolute Maximum Ratings Voltage Range on VCC Relative to Ground..........-0.5V to +6.0V Voltage Range on Input Pins Relative to Ground............................... -0.5V to (VCC + 0.5V), not to exceed 6.0V Operating Temperature Range............................ -40C to +85C Storage Temperature Range............................. -55C to +125C Soldering Temperature.......................................See IPC/JEDEC J-STD-020A 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 DC Operating Conditions (TA = -40C to +85C) PARAMETER SYMBOL MAX UNITS 3.0 5.5 V VIH 0.7 x VCC VCC + 0.3 V VIL -0.3 +0.3 x VCC V TYP 1.4 MAX UNITS 1.7 3 Supply Voltage VCC Input Logic 1 (J0, J1, JC0, JC1) Input Logic 0 (J0, J1, JC0, JC1) CONDITIONS (Note 1) MIN TYP DC Electrical Characteristics (VCC = +3.0V to +5.5V, TA = -40C to +85C, unless otherwise noted.) PARAMETER SYMBOL Supply Current ICC High-Level Output Voltage (OUT) VOH Low-Level Output Voltage (OUT) VOL CONDITIONS CL = 15pF, VCC = 3.3V, RSET = 40k CL = 15pF, VCC = 5.5V, RSET = 40k IOH = -4mA VCC = min V +1.0 A VIH = VCC Low-Level Input Current (J0, J1, JC0, JC1) IIL VIL = 0V www.maximintegrated.com V 0.4 IIH IRES 2.4 mA IOL = 4mA High-Level Input Current (J0, J1, JC0, JC1) Resistor Current MIN VCC = max -1.0 A 150 A Maxim Integrated 2 DS1090 Low-Frequency, Spread-Spectrum EconOscillator AC Electrical Characteristics (VCC = +3.0V to +5.5V, TA = -40C to +85C, unless otherwise noted.) PARAMETER SYMBOL Internal Master Oscillator Frequency fMOSC Output Frequency Tolerance fOUT Voltage Frequency Variation Temperature Frequency Variation fOUT fOUT Peak-to-Peak Dither (3) (Note 5) Power-Up Time Load Capacitance Note Note Note Note Note MIN MAX UNITS 4.0 8.0 MHz VCC = 3.3V, TA = +25C -3.0 +3.0 % TA = +25C, RSET = 60k, VCC = 3.0V to 3.6V (Notes 2, 3) -0.5 +0.5 TA = +25C, RSET = 60k, VCC = 4.5V to 5.5V (Notes 2, 3) -1.25 +1.25 VCC = 3.3V (Notes 2, 3, 4) -2.0 +2.0 J0 = GND, J1 = GND 0 J0 = VCC, J1 = GND 2 J0 = VCC, J1 = VCC 8 tPOR + tSTAB (Note 6) CL (Note 7) 4MHz to 8MHz, TA = +25C (Note 3) <4MHz (Note 4) tR, tF TYP % CL = 15pF 0.1 45 % % 4 J0 = GND, J1 = VCC Output Duty Cycle Output Rise/Fall Time CONDITIONS 0.5 ms 30 pF 55 50 20 % ns 1: 2: 3: 4: 5: All voltages referenced to ground. This is the change observed in output frequency due to changes in temperature or voltage. See the Typical Operating Characteristics section. Parameter is guaranteed by design and is not production tested. This is a percentage of the output period. Parameter is characterized but not production tested. This can be varied from 0% to 8%. Note 6: This indicates the time between power-up and the outputs becoming active. An on-chip delay is intentionally introduced to allow the oscillator to stabilize. tSTAB is equivalent to ~500 clock cycles and is dependent upon the programmed output frequency. Note 7: Output voltage swings can be impaired at high frequencies combined with high output loading. www.maximintegrated.com Maxim Integrated 3 DS1090 Low-Frequency, Spread-Spectrum EconOscillator Typical Operating Characteristics (VCC = +3.3V, TA = +25C, unless otherwise noted.) 40k 60k 0.95 1.10 60k 0.90 0.70 4.0 4.5 5.0 DS1090 toc03 4V 2 3V 1 0.50 5.5 -40 -15 10 35 60 0 85 5 10 15 20 25 30 35 SUPPLY VOLTAGE (V) TEMPERATURE (C) LOAD CAPACITANCE (pF) OUTPUT VOLTAGE HIGH vs. OUTPUT CURRENT OUTPUT VOLTAGE LOW vs. OUTPUT CURRENT OUTPUT FREQUENCY vs. SUPPLY VOLTAGE 0.4 DS1090 toc04 VCC = 3.0V OUTPUT VOLTAGE (V) 3.0 VCC = 3.0V 2.9 2.8 10 0.3 TA = +25C 9 0.2 40 DS1090 toc06 3.5 FREQUENCY (MHz) 3.0 5V 3 80k 80k 3.1 OUTPUT VOLTAGE (V) 40k TA = +25C, RSET = 40k DS1090 toc05 0.70 1.30 SUPPLY CURRENT vs. OUTPUT LOADING 4 SUPPLY CURRENT (mA) 1.45 NO LOAD, VCC = 3.3V SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) NO LOAD, TA = +25C 1.20 1.50 DS1090 toc01 1.70 SUPPLY CURRENT vs. TEMPERATURE DS1090 toc02 SUPPLY CURRENT vs. SUPPLY VOLTAGE 40k 8 7 60k 80k 6 0.1 5 2.7 -5 -4 -3 -2 OUTPUT CURRENT (mA) www.maximintegrated.com -1 0 0 0 1 2 3 OUTPUT CURRENT (mA) 4 5 4 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) Maxim Integrated 4 DS1090 Low-Frequency, Spread-Spectrum EconOscillator Typical Operating Characteristics(continued) (VCC = +3.3V, TA = +25C, unless otherwise noted.) 8 7 60k 80k VCC = 3.3V 50 VCC = 5V 49 5 10 35 60 -15 10 35 DS1090 toc09 14 12 10 FREQUENCY ERROR (%) 40k 3.5 2.0 DS1090 toc10 0 60k 4.0 4.5 SUPPLY VOLTAGE (V) www.maximintegrated.com 60k 5.5 70 80 0 80k -1.0 -30 -40 -50 VCC = 3.3V, TA = +25C, JC0 = JC1 = 1 OFF -10 -20 2% 4% 8% -60 40k 5.0 60 POWER SPECTRUM vs. SPREAD 0 1.0 -2.0 50 40 RSET (k) FREQUENCY ERROR vs. TEMPERATURE (FROM +25C) VCC = 3.3V 8 85 60 FREQUENCY ERROR vs. SUPPLY VOLTAGE (FROM 3.3V) 80k 3.0 -40 TEMPERATURE (C) 2.5 -2.5 48 85 TEMPERATURE (C) TA = +25C FREQUENCY ERROR (%) 16 DS1090 toc12 -15 POWER (dBm) -40 5.0 -5.0 VCC = 3.3V, TA = +25C DS1090U-1 DS1090 toc11 4 18 RESISTOR CURRENT (mA) 51 40k DUTY CYCLE (%) FREQUENCY (MHz) 9 RSET = 40k DS1090 toc08 VCC = 3.3V 6 52 DS1090 toc07 10 RESISTOR CURRENT vs. RESISTOR VALUE DUTY CYCLE vs. TEMPERATURE OUTPUT FREQUENCY vs. TEMPERATURE -40 -15 10 35 TEMPERATURE (C) -70 60 85 -80 4.80 5.35 5.90 FREQUENCY (MHz) Maxim Integrated 5 DS1090 Low-Frequency, Spread-Spectrum EconOscillator Pin Description PIN 1 NAME OUT FUNCTION Oscillator Output 2 RSET Frequency Control Resistor Input 4 GND Ground 5 J0 6 J1 3 VCC Positive-Supply Terminal Dither Amplitude (Percentage) Inputs (see Table 2) 7 JC0 8 JC1 Dither Rate Divisor Inputs (see Table 1) Block Diagram DS1090 RSET VOLTAGEBIAS CIRCUIT MASTER OSCILLATOR (VCO) + fMOSC + FACTORY PROGRAMMED PRESCALER fOSC BUFFER fOUT OUT ( 1, 2, 4, 8, 16, OR 32) 4MHz-8MHz VCC VCC GND DITHER GENERATOR + - TRIANGLE GENERATOR DITHER AMPLITUDE (0, 2, 4, OR 8%) f MOD ( 128) DITHER RATE ( 4, 8, 16, OR 32) J0 J1 JC0 JC1 www.maximintegrated.com Maxim Integrated 6 DS1090 Low-Frequency, Spread-Spectrum EconOscillator DITHER AMOUNT (2, 4, OR 8%) (- 1, 2, or 4% of fMOSC) 1 fMOD fMOSC fMOSC (MHz) 8 IF DITHER AMOUNT = 0% (+ 1, 2, or 4% of fMOSC) Programmed fMOSC DS1090 fig01 9 MASTER OSCILLATOR FREQUENCY vs. EXTERNAL RESISTOR SELECTION 7 6 TIME 5 Figure 2. Center Frequency Dither Diagram 4 3 Factory-Programmed Prescaler 40 50 60 70 80 90 RSET RESISTANCE (k) Figure 1. Master Oscillator Frequency Detailed Description The DS1090 is a center-dithered, spread-spectrum silicon oscillator for use as an external clock in reduced-EMI applications. With a combination of factory-programmed prescalers and a user-selected external resistor, output frequencies from 125kHz to 8MHz can be achieved. The output center frequency can be dithered by selecting the desired dither rate and amplitude with discrete inputs J0, J1, JC0, and JC1. The DS1090 contains four basic circuit blocks: master oscillator, factory-programmed prescaler, dither generator, and the voltage-bias circuit that provides the feedback path to the master oscillator for frequency control and dithering functions. Master Oscillator The master oscillator is programmable in the application by the use of an external resistor (RSET) tied to ground (GND). Resistor values of 45k to 91k vary the square-wave output frequency of the voltage-controlled master oscillator (fMOSC) from 8MHz down to 4MHz (see Figure 1). The master oscillator (Hz) frequency can be stated as f MOSC www.maximintegrated.com 3.6461E+11 Resistor The prescaler divides the frequency of the master oscillator by 1, 2, 4, 8, 16, or 32 to generate the square-wave output clock (fOSC). This divisor is factory-set and is an ordering option. Dither Generator Spread-spectrum functionality is achieved by a userconfigurable divider (determines dither rate), a triangle generator, and a user-configurable dither amplitude circuit (see Block Diagram). The input to the triangle-wave generator is derived from the internal master oscillator and is fed through a user-configurable divider. The settings of control pins JC0 and JC1 determine this dither rate divisor setting (see Table 1), dividing the master clock by 4, 8, 16, or 32. The clock signal is further divided by 128 in the triangle-wave generator, which results in a triangle-wave signal of either 1/512th, 1/1024th, 1/2048th, or 1/4096th of the master oscillator (fMOD), depending upon the user's divisor setting. The dithering frequency can be also expressed as the result of f MOD = f MOSC Divisor x 128 where Divisor is 4, 8, 16, or 32. Table 1. Dither Rate Divisor Settings JC1 JC0 0 0 0 1 1 0 1 1 DITHERING PERCENTAGE (fMOSC/n) fMOSC /512 fMOSC /1024 fMOSC /2048 fMOSC /4096 DIVISOR SETTING 4 8 16 32 Maxim Integrated 7 DS1090 Low-Frequency, Spread-Spectrum EconOscillator Table 2. Dither Percentage Setting J1 J0 DITHER PERCENT (%) 0 0 0 0 1 2 1 0 4 1 1 8 Dither Percentage Settings RSET Resistor Selection The value of the resistor used to select the desired frequency is calculated using the formula in the Master Oscillator section (see also Figure 1). It is recommended to use, at minimum, a 1%-tolerance, 1/16th-watt component with a temperature coefficient that satisfies the overall stability requirements desired of the end-equipment. Place the external RSET resistor as close as possible to minimize lead inductance. Dither amplitude (measured in percent from the master oscillator center frequency) is set using input pins J0 and J1. This circuit uses a sense current from the master oscillator bias circuit to adjust the amplitude of the triangle-wave signal to a voltage level that modulates the master oscillator to a percentage of its resistor-set center frequency. This percentage is set in the end application to be 0%, 2%, 4%, or 8% (see Table 2). 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 0.01F and 0.1F. 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. Application Information Chip Information Pin Connection The DS1090 is intended to provide a fixed-frequency, dithered clock to be used as a clock driver for DC-DC converters and other applications requiring a lowfrequency EMI-reduced clock oscillator. All control pins must be biased per Tables 1 and 2 for proper operation for the individual application's requirements. RSET must be tied to ground (GND) by a customer-supplied resistor. www.maximintegrated.com Power-Supply Decoupling SUBSTRATE CONNECTED TO GROUND Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. Maxim Integrated 8 DS1090 Low-Frequency, Spread-Spectrum EconOscillator Revision History REVISION NUMBER REVISION DATE 1 2/07 -- -- 2 2/15 Remove automotive reference from data sheet 1 3 9/16 Corrected typo in Benefits and Features section 1 DESCRIPTION PAGES CHANGED For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated's website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. (c) 2016 Maxim Integrated Products, Inc. 9 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Maxim Integrated: DS1090U-1+ DS1090U-1+T DS1090U-16+ DS1090U-16+T DS1090U-2+ DS1090U-2+T DS1090U-32+ DS1090U-32+T DS1090U-4+ DS1090U-4+T DS1090U-8+T DS1090U-2/V+ DS1090U-8+ DS1090U-2/V+T DS1090U-8/V+ DS1090U-8/V+T