SI9174

Si9174 Vishay Siliconix High Performance Step-Down DC-DC Converter With Dynamically Adjustable Output Voltage D D D D D D D D D D D D D D FEATURES 2-MHz PWM Operation Integrated MOSFET Switches 2.6-V to 6.0-V Input Voltage Range Minimal Number of External Components Up to 96% conversion efficiency 600-mA Load Capability 100% Duty Cycle Allows Low Dropout Integrated Compensation Circuit Over-Current Protection Shutdown Current < 2 mA Thermal Shutdown Integrated UVLO 10-Pin MSOP and Space Saving MLP33 Packaging DAC Input for Dynamic Output Voltage Adjustment D Synchronizable to13-MHz Clock D User Selectable PWM, PSM, or AUTO Mode D PSM Frequency w20 kHz for Inaudible Harmonics APPLICATIONS D D D D D D D D D W-CDMA Cell Phone PDAs/Palmtop PCs LCD Modules Portable Image Scanners GPS Receivers Smart Phones MP3 Players 3G Cell Phone Digital Cameras DESCRIPTION The Si9174 is a high efficiency 600-mA step down converter with internal low on resistance power MOSFET switch and synchronous rectifier transistors. It is designed to convert one cell LiIon battery or three cell alkaline battery voltages to a dynamically adjustable dc output. The voltage on the DAC pin controls the output voltage. The output voltage is adjustable between 0.4 V and the input voltage VIN less a small dropout voltage and settles in 2.6, VIN − VDAC > 0.5 V VFB = 1.25 V VDAC −20 0.28 −1 0.01 VDAC +20 2.45 1 mV V mA 2 Document Number: 71668 S-41148—Rev. C, 14-jun-04 Si9174 Vishay Siliconix SPECIFICATIONS Parameter Modef Converter Operation Maximum Output Current Maximum Output Current Dropout Voltagee Closed Loop Bandwidth Load Regulationc Line Regulation PWM PSM PWM PSM IAUpk ILpk Negative Transition on VDAC rDS( ) DS(on) VIN = 3.6 V 6 0.05 0 05 W COUT(ESR) VIN = 3.6 V, VOUT = 3.3 V 6V 3 IOUT w 30 mA IOUT = 600 mA IOUT = 30 mA IOUT = 600 mA IOUT = 30 mA 20 PWM PSM ILOAD ILOAD VDD BW VIN = 3.6 V .6 VOUT = 1.9 V @ 25_C IOUT = 30 mA to 600 mA IOUT = 30 mA to 75 mA VIN = 3.6 V VIN = 3.6 V VIN = 2.6 V, IOUT = 600 mA 190 300 0.5 0.25 "0.1 "0.1 200 1500 1500 250 250 60 80 90 80 mW mVp-p % kHz mA 600 150 300 mA mA mV kHz % %/V Test Conditions Unless Specified Symbol −40_C to 85_C, VIN = VDD, VDAC = 1.215 V, CIN = 10 mF, COUT = 4.7 mF, L = 2.2 mH, 2.6 V v VIN v 5.5 V R1 = 11.3 kW, R2 = 20 kW Limits Mina Typb Maxa Unit VOUT = 3.0 V, VIN = 3.5 V to 5 5 V 0V 5 5.5 PWM/PSM Switch Threshold Current Maximum Inductor Peak Current Limit Maximum NMOS Transistor Current Sink On Resistance Output Ripple Voltage Efficiency Frequency PWM P-Channel N-Channel PWM PSM PWM PSM PSM Supply Current Input Supply Current Shutdown Supply Current PWM PSM ISUPPLY (VDD & VIN) ISD IOUT = 0 mA VIN = 3.6 V (not switching FB = GND) A, 6 switching, SD = Low 500 400 2 800 mA Thermal Shutdown Thermal Shutdown Temperaturec Thermal Hysteresisc TJ(S/D) 165 20 _C Notes a. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum, is used in this data sheet. b. Typical values are for DESIGN AID ONLY, not guaranteed or subject to production testing. c. Guaranteed by design. d. Settling times, ts, apply after ten. e. Bypass is a device mode of operation, in which, the device is in 100% duty cycle. Bypass operation is possible in either PWM or PSM. f. Operating modes are controlled with the MODE pin where Auto mode = MODE = LOW, PWM Mode = MODE = HIGH, and PSM mode = MODE = OPEN. Document Number: 71668 S-41148—Rev. C, 14-jun-04 www.vishay.com 3 Si9174 Vishay Siliconix PIN CONFIGURATION MSOP-10 LX AGND FB VDD DAC 1 2 3 4 5 10 9 8 7 6 MLP33 PGND VIN SYNC SD MODE LX AGND FB VDD DAC 10 9 8 7 6 PGND VIN SYNC SD MODE 2 3 4 5 Top View Top View PIN DESCRIPTION Pin Number 1 2 3 4 5 Name LX AGND FB VDD DAC Inductor connection Low power analog ground Output voltage feedback Input supply voltage for the analog circuit. Voltage from external DAC to adjust output voltage. Used to select switching mode of the buck converter PWM/PSM Pin Logic: Function 6 MODE MODE Pin VIN Open GND Operating Mode PWM PSM AUTO 7 8 9 10 SD SYNC VIN PGND Logic low disables IC and reduces quiescent current to below 2 mA Converter switching frequency can be synchronized to 1/6 of the clock frequency at this pin. Input supply voltage Low impedance power ground ORDERING INFORMATION MSOP-10 Standard Part Number Si9174DH-T1 MLP33 Temperature −40 to 85_C Marking 9174 Standard Part Number Si9174DM-T1 Lead (Pb)-Free Part Number Si9174DM-T1—E3 Marking 9174 Temperature −40 to 85_C Additional voltage options are available. Eval Kit Si9174DB Temperature Range −40 to 85_C Board Surface Mount www.vishay.com 4 Document Number: 71668 S-41148—Rev. C, 14-jun-04 Si9174 Vishay Siliconix FUNCTIONAL BLOCK DIAGRAM VDD Si9174 VIN PMOS Current Sense Error Amplifier − + Clamp − + FB DAC PWM Comparator PWM and Pulse Skipping Logic LX To IC Bias Voltage Reference UVLO B6 2 MHz Oscillator NMOS Current Sense AGND SYNC MODE SD PGND DETAIL DESCRIPTION General The Si9174 is a high efficiency synchronous dc-dc converter that is ideally suited for lithium ion battery or three cell alkaline applications, as well as step-down of 3.3-V or 5.0-V supplies. It is design to provide power to the power amplifier in WCDMA cell phones, but can utilized in any applications requiring a dynamically adjustable 600-mA power supply. The major blocks of the Si9174 are shown in the Functional Block Diagram. The 0.25-W internal MOSFETs switching at a frequency of 2-MHz minimize PC board space while providing high conversion efficiency and performance. The high frequency error-amplifier with built-in loop compensation minimizes external components and provides rapid output settling times of