SP6669 600mA 1.5MHz Synchronous Step Down Converter February 2012 Rev. 2.1.0 GENERAL DESCRIPTION The SP6669 is a synchronous current mode PWM step down (buck) converter capable of delivering up to 600mA of current. It features a pulse skip mode (PSM) for light load efficiency and a LDO mode for 100% duty cycle. With a 2.5V to 5.5V input voltage range and a 1.5MHz switching frequency, the SP6669 allows the use of small surface mount inductors and capacitors ideal for battery powered portable applications. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. The SP6669 is available in an adjustable output voltage version, using an external resistor divider circuit, as well as fixed output voltage versions of 1.2V, 1.5V and 1.8V. Built-in over temperature and output over voltage lock-out protections insure safe operations under abnormal operating conditions. The SP6669 is offered in a RoHS compliant, "green"/halogen free 5-pin SOT23 package. APPLICATIONS Portable Equipments Battery Operated Equipments Audio-Video Equipments Networking & Telecom Equipments FEATURES Guaranteed 600mA Output Current Input Voltage: 2.5V to 5.5V 1.5MHz PWM Current Mode Control 100% Duty Cycle LDO Mode Operations Achieves 95% Efficiency Fixed/Adjustable Output Voltage Range As Low as 0.6V with 3% Accuracy 1.2V, 1.5V, 1.8V Fixed Voltage Options Excellent Line/Load Transient Response 200A Quiescent Current Over Temperature Protection RoHS Compliant "Green"/Halogen Free 5-Pin SOT23 Package TYPICAL APPLICATION DIAGRAM Fig. 1: SP6669 Application Diagram (Adj. version shown) Exar Corporation 48720 Kato Road, Fremont CA 94538, USA www.exar.com Tel. +1 510 668-7000 - Fax. +1 510 668-7001 SP6669 600mA 1.5MHz Synchronous Step Down Converter ABSOLUTE MAXIMUM RATINGS OPERATING RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. Input Voltage Range VIN ............................... 2.7V to 5.5V Operating Temperature Range ................... -40C to 85C Thermal Resistance JA .....................................250C/W Thermal Resistance Jc....................................... 90C/W Input Voltage VIN ....................................... -0.3V to 6.0V Enable VFB Voltage ....................................... -0.3V to VIN SW Voltage ...................................... -0.3V to (VIN+0.3V) PMOS Switch Source Current (DC) ........................ 800mA NMOS Switch Sink Current .................................. 800mA Peak Switch Sink/Source Current ............................ 1.3A Operating Junction Temperature1 .......................... 125C Storage Temperature .............................. -65C to 150C Lead Temperature (Soldering, 10 sec) ................... 240C ESD Rating (HBM - Human Body Model) .................... 2kV ESD Rating (MM - Machine Model) ...........................200V Note 1: TJ is a function of the ambient temperature TA and power dissipation PD (TJ= TA + PD x 250C/W). ELECTRICAL SPECIFICATIONS Specifications with standard type are for an Operating Junction Temperature of TJ = 25C only; limits applying over the full Operating Junction Temperature range are denoted by a "*". Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TA = 25C, and are provided for reference purposes only. Unless otherwise indicated, VIN = 3.6V. Parameter Min. Typ. Max. Units 30 nA 0.588 0.600 0.612 V 0.4 %/V * * Feedback Current IVFB Regulated Feedback Voltage VFB Reference Voltage Line Regulation VFB Conditions TA=25C VIN=2.5V to 5.5V Output Voltage Accuracy VOUT% -3 +3 % Output Over-Voltage Lockout VOVL 20 50 80 mV VOVL = VOVL - VFB (Adj.) 2.5 7.8 13 % VOVL = VOVL - VOUT (Fixed) 0.4 %/V Output Voltage Line Regulation VOUT Peak Inductor Current IPK 1.0 A Output Voltage Load Regulation VLOADREG 0.5 % 2 * VIN=2.5V to 5.5V VIN=3V, VFB=0.5V or VOUT=90%, Duty cycle <35% Quiescent Current IQ 200 340 A Shutdown Current ISHTDWN 0.1 1 A 1.5 1.8 MHz * VFB=0.6V or VOUT=100% Hz * VFB=0V or VOUT=0V Oscillator Frequency fOSC 1.2 290 VFB=0.5V or VOUT=90% VEN=0V, VIN=4.2V RDS(ON) of PMOS RPFET 0.45 0.55 ISW=100mA RDS(ON) of NMOS RNFET 0.40 0.50 ISW=100mA SW Leakage ILSW 1 A Enable Threshold VEN 1.2 V * V * 1 A * Shutdown Threshold VEN EN Leakage Current IEN 0.4 VEN=0V, VSW=0V or 5V, VIN=5V Note 1: The Switch Current Limit is related to the Duty Cycle. Please refer to figure 15 for details. Note 2: Dynamic quiescent current is higher due to the gate charge being delivered at the switching frequency. (c) 2012 Exar Corporation 2/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter BLOCK DIAGRAM Fig. 2: SP6669 Block Diagram PIN ASSIGNMENT Fig. 3: SP6669 Pin Assignment (c) 2012 Exar Corporation 3/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter PIN DESCRIPTION Name Pin Number Description EN 1 Enable Pin. Do not leave the pin floating. VEN<0.4V: Shutdown mode VEN>1.2V: Device enabled GND 2 Ground Signal SW 3 Switching Node VIN 4 Power Supply Pin. Must be decoupled to ground with a 4.7F or greater ceramic capacitor. Adjustable Version Feedback Input Pin. Connect VFB to the center point of the resistor divider. VFB 5 VOUT Fixed Output Voltage Version, Output Voltage Pin. An internal resistive divider divides the output voltage down for comparison to the internal reference voltage. ORDERING INFORMATION Temperature Range Marking Package Packing Quantity SP6669AEK-L/TRR3 -40CTA+85C QBWW SOT23-5 3K/Tape & Reel Halogen Free SP6669BEK-L/TRR3 -40CTA+85C RBWW SOT23-5 3K/Tape & Reel Halogen Free SP6669CEK-L/TRR3 -40CTA+85C SBWW SOT23-5 3K/Tape & Reel Halogen Free SP6669DEK-L/TRR3 -40CTA+85C TBWW SOT23-5 3K/Tape & Reel Halogen Free Part Number SP6669EB Note 1 Note 2 Adjustable output voltage 1.2V fixed output voltage 1.5V fixed output voltage 1.8V fixed output voltage SP6669 Evaluation Board "YY" = Year - "WW" = Work Week - "X" = Lot Number; when applicable. Note that the SP6669 series is packaged in Tape and Reel with a reverse part orientation as per the following diagram (c) 2012 Exar Corporation 4/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter TYPICAL PERFORMANCE CHARACTERISTICS All data taken at VIN = 2.7V to 5.5V, TJ = TA = 25C, unless otherwise specified - Schematic and BOM from Application Information section of this datasheet. Fig. 4: Efficiency vs Output Current (mA) Fig. 5: Efficiency vs Output Current (mA) Fig. 6: Efficiency vs Output Current (mA) Fig. 7: Efficiency vs Output Current (mA) Fig. 8: Output Voltage vs Load Current Fig. 9: Reference Voltage vs Temperature (c) 2012 Exar Corporation 5/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter Fig. 10: RDS(ON) vs Temperature Fig. 11: RDS(ON) vs Input Voltage Fig. 12: Dynamic Supply Current vs Temperature Fig. 13: Dynamic Supply Current vs Supply Voltage Fig. 14: Oscillator Frequency vs Temperature Fig. 15: Oscillator Frequency vs Supply Voltage (c) 2012 Exar Corporation 6/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter Fig. 16: Discontinuous Operation Fig. 17: Start-up from Shutdown Fig. 18: Load Step Fig. 19: Load Step Fig. 20: Load Step Fig. 21: Load Step (c) 2012 Exar Corporation 7/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter THEORY OF OPERATION Eq. 3: APPLICATIONS 1 VOUT I L ESR 8 f COUT Higher values, lower cost ceramic capacitors are now available in smaller sizes. These capacitors have high ripple currents, high voltage ratings and low ESR that makes them ideal for switching regulator applications. As COUT does not affect the internal control loop stability, its value can be optimized to balance very low output ripple and circuit size. It is recommended to use an X5R or X7R rated capacitors which have the best temperature and voltage characteristics of all the ceramics for a given value and size. The typical application circuit of the adjustable output voltage option and the fixed output voltage option are shown below. Fig. 22: Adjustable Output Voltage Version OUTPUT VOLTAGE - ADJUSTABLE VERSION The adjustable determined by: Eq. 4: Fig. 23: Fixed Output Voltage Version version is R VOUT 0.6V 1 2 R1 Although the SP6669 has an on board over temperature circuitry, the total power dissipation it can support is based on the package thermal capabilities. The formula to ensure safe operation is given in note 1. Inductor ripple current and core saturation are two factors considered to select the inductor value. I L voltage THERMAL CONSIDERATIONS INDUCTOR SELECTION Eq. 1: output V 1 VOUT 1 OUT f L VIN PCB LAYOUT Equation 1 shows the inductor ripple current as a function of the frequency, inductance, VIN and VOUT. It is recommended to set the ripple current between 30% to 40% of the maximum load current. A low ESR inductor is preferred. The following PCB layout guidelines should be taken into account to ensure proper operation and performance of the SP6669: CIN AND COUT SELECTION 2- VFB pin must be connected directly to the feedback resistors. The resistor divider network must be connected in parallel to the COUT capacitor. 1- The GND, SW and VIN traces should be kept short, direct and wide. A low ESR input capacitor can prevent large voltage transients at VIN. The RMS current rating of the input capacitor is required to be larger than IRMS calculated by: Eq. 2: I RMS I OMAX 3- The input capacitor CIN must be kept as close as possible to the VIN pin. VOUT VIN VOUT 4- The SW and VFB nodes should be kept as separate as possible to minize possible effects from the high frequency and voltage swings of the SW node. VIN The ESR rating of the capacitor is an important parameter to select COUT. The output ripple VOUT is determined by: (c) 2012 Exar Corporation 8/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter 5- The ground plates of CIN and COUT should be kept as close as possible. DESIGN EXAMPLE OUPTUT VOLTAGE RIPPLE FOR VIN CLOSE TO VOUT In a single Lithium-Ion battery powered application, the VIN range is about 2.7V to 4.2V. The desired output voltage is 1.8V. When the input voltage VIN is close to the output voltage VOUT, the SP6669 transitions smoothly from the switching PWM converter mode into a LDO mode. The following diagram shows the output voltage ripple versus the input voltage for a 3.3V output setting and a 200mA current load. The inductor value needed can be calculated using the following equation L V 1 VOUT 1 OUT f I L VIN Substituting VOUT=1.8V, VIN=4.2V, IL=180mA to 240mA (30% to 40%) and f=1.3MHz gives A 3.3H inductor can be chosen with this application. An inductor of greater value with less equivalent series resistance would provide better efficiency. The CIN capacitor requires an RMS current rating of at least ILOAD(MAX)/2 and low ESR. In most cases, a ceramic capacitor will satisfy this requirement. Fig. 24: VOUT Ripple Voltage for VIN decreasing close to VOUT (c) 2012 Exar Corporation 9/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter PACKAGE SPECIFICATION 5-PIN SOT23 Unit: mm Symbol Min. Nom. Max A 0.90 1.30 1.40 A1 0.00 0.075 0.15 A2 0.90 1.20 1.25 b 0.30 - 0.50 c 0.08 - 0.20 D 2.80 2.90 3.00 E 2.60 2.80 3.00 E1 1.50 1.60 1.70 0.95 BSC e 1.90 BSC e1 L 0.30 0.45 L1 0.60 REF L2 0.25 BSC 0.60 0 5 10 1 3 5 7 2 6 8 10 Note: JEDEC Outline MO-178 AA (c) 2012 Exar Corporation 10/11 Rev. 2.1.0 SP6669 600mA 1.5MHz Synchronous Step Down Converter REVISION HISTORY Revision Date Description 2.0.0 07/15/2011 Reformat of datasheet Updated package specification 2.1.0 02/07/2012 Updated Typical Application schematics and Design example FOR FURTHER ASSISTANCE Email: customersupport@exar.com Exar Technical Documentation: http://www.exar.com/TechDoc/default.aspx? EXAR CORPORATION HEADQUARTERS AND SALES OFFICES 48720 Kato Road Fremont, CA 94538 - USA Tel.: +1 (510) 668-7000 Fax: +1 (510) 668-7030 www.exar.com NOTICE EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary depending upon a user's specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. or its in all Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. (c) 2012 Exar Corporation 11/11 Rev. 2.1.0