Si9175 Vishay Siliconix New Product High Performance Step-Down DC-DC Converter With Adjustable Output Voltage FEATURES D D D D D D D D D D D D D D Synchronizable to13-MHz Clock D User Selectable PWM, PSM, or AUTO Mode D PSM Frequency ≥20 kHz for Inaudible Harmonics 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 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 Si9175 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 integrated high frequency error amplifier with internal compensation minimizes external components. In order to insure efficient conversion throughout the entire load range, PWM (pulse width modulation), PSM (pulse skipping mode) or Auto mode can be selected. In PWM mode, 2-MHz switching permits use of small external inductor and capacitor sizes allowing one of the smallest solutions. To minimize system noise, the switching frequency can be synchronized to an external 13-MHz clock. PSM mode provides increased efficiency at light loads. In PSM mode the oscillator frequency is kept above 20 kHz to avoid audio band interference. When operating in Auto mode, the converter automatically selects operating in either PWM or PSM mode according to load current demand. The Si9175 is available in 10-pin MSOP and even smaller MLP33 packages and is specified to operate over the industrial temperature range of –40_C to 85_C. TYPICAL APPLICATIONS CIRCUIT BATTERY VIN 2.2 mH LX VDD CIN 10 mF COUT 4.7 mF Si9175 VOUT R1 PGND 13 MHz SYNC FB ENABLE PWM/PSM/AUTO Document Number: 71728 S-21823—Rev. A, 07-Oct-02 SD MODE REF AGND REF R2 www.vishay.com 1 Si9175 Vishay Siliconix New Product ABSOLUTE MAXIMUM RATINGS Voltages Referenced to AGND = 0 V VIN, VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 V Lx, SD, MODE, FB, CREF, SYNC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . --0.3 to 6.2 V (or to VDD +0.3 V whichever is less) GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . --0.3 to +0.3 V ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . --65 to 125_C Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150_C Power Dissipation (Package)a 10-pin MSOPb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481 mW 10-pin MLP33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915 mW Thermal Impedance (ΘJA) 10-Pin MSOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135_C/W 10-Pin MLP33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71_C/W Peak Inductor Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 A Notes a. Device mounted with all leads soldered or welded to PC board. b. Derate 7.4 mW/_C above 85_C. c. Derate 14 mW/_C above 85_C. 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 RANGE VIN Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 V to 5.5 V Inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 mH CIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mF Ceramic Operating Load Current PWM Mode . . . . . . . . . . . . . . . . . . . . . . 0 to 600 mA COUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 mF Ceramic Operating Load Current PSM Mode . . . . . . . . . . . . . . . . . . . . . . . 0 to 150 mA SPECIFICATIONS Test Conditions Unless Specified Parameter Modef Symbol Limits --40_C to 85_C, VIN = VDD,, CIN = 10 mF, COUT = 4.7 mF L = 2.2 mH, 2.6 V ≤ VIN ≤ 5.5 V, R1 = 11.3 kΩ, R2 = 20 kΩ Mina VIN rising 2.3 Typb Maxa Unit Under Voltage Lockout (UVLO) Under Voltage Lockout (turn-on) Hysteresis 2.5 0.1 V Shutdown (SD) Logic HIGH VSDH Logic LOW VSDL Delay to Outputc ten Pull Down ISD 1.6 0.4 RL = 3.3 Ω Settle Within ±2% accuracy SD rising tr < 1 ms 100 RL = 51 Ω 100 Input at VIN V ms mA Mode Selection Tri-Level Logic (MODE) MODE Pin HIGH PWM MODE Pin LOW Auto VIN --0.4 VIN 0.4 Mode Pin Input Current MODE = GND --5 MODE = VIN 5 V mA Oscillator Frequency fOSC 1.6 2 2.4 MHz External Clock Synchronization (SYNC) Frequency SYNC Input = 500 mVp-p Ac Coupled Sinewave 13 Frequency = 13 MHz 0.2 MHz 0.8 Vp-p Error Amplifier (FB Pin) FB Voltage Accuracy Power Supply Rejection Input Bias Current www.vishay.com 2 VFB PSRR VIN = 2.6 V to 5.5 VDC IFB VFB = 1.25 V TA = 25_C 1.190 TA = --40 to 85_C 1.173 1.215 1.240 1.257 60 --1 0.01 V db 1 mA Document Number: 71728 S-21823—Rev. A, 07-Oct-02 Si9175 Vishay Siliconix New Product SPECIFICATIONS Test Conditions Unless Specified Parameter Modef Symbol --40_C to 85_C, VIN = VDD,, CIN = 10 mF, COUT = 4.7 mF L = 2.2 mH, 2.6 V ≤ VIN ≤ 5.5 V, R1 = 11.3 kΩ, R2 = 20 kΩ Maximum Output Current PWM ILOAD VIN = 3.6 V Maximum Output Current PSM ILOAD VIN = 3.6 V Dropout Voltagee VDD VIN = 2.6 V, IOUT = 600 mA Closed Loop Bandwidth BW Limits Mina 600 Typb Maxa Unit Converter Operation Load Regulationc Line Regulation PWM PWM 150 190 IOUT = 30 mA to 600 mA 0.5 IOUT = 30 mA to 75 mA 0.25 IAUpk 200 Maximum Inductor Peak Current Limit ILpk 1500 On Resistance Output Ripple Voltage Efficiency Frequency P-Channel N-Channel rDS(on) DS( ) PWM 0 05 Ω COUT(ESR) 0.05 PSM PWM VIN = 3 3.6 6 V, V VOUT = 3 3.3 3V PSM PSM %/V mA 250 VIN = 3 3.6 6V mΩ 250 IOUT = 600 mA 60 IOUT = 30 mA 80 IOUT = 600 mA 90 IOUT = 30 mA 80 IOUT ≥ 30 mA mV % 0.1 PWM/PSM Switch Threshold Current mA kHz 0.1 VOUT = 3 3.0 0 V, V VIN = 3 3.5 5 V to 5.5 55V PSM 300 300 VIN = 3.6 V VOUT = 1.9 V @ 25_C PSM mA mVp-p % 20 kHz Supply Current Input Supply Current PWM PSM Shutdown Supply Current ISUPPLY (VDD & VIN) IOUT = 0 mA, mA VIN = 3 3.6 6 V (not switching, switching FB = GND) ISD SD = Low 450 750 mA 400 2 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: 71728 S-21823—Rev. A, 07-Oct-02 www.vishay.com 3 Si9175 Vishay Siliconix New Product PIN CONFIGURATION MSOP-10 MLP33 LX 1 10 PGND AGND 2 9 VIN FB 3 8 SYNC VDD 4 7 SD REF 5 6 MODE LX AGND FB VDD REF 10 9 8 7 6 2 3 4 5 PGND VIN SYNC SD MODE Top View Top View PIN DESCRIPTION Pin Number Name 1 LX 2 AGND Function Inductor connection Low power analog ground 3 FB Output voltage feedback 4 VDD Input supply voltage for the analog circuit. 5 REF Internal reference, no connection should be made to this pin. Used to select switching mode of the buck converter PWM/PSM Pin Logic: 6 MODE 7 SD 8 SYNC 9 VIN 10 PGND MODE Pin VIN Open GND Operating Mode PWM PSM AUTO 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 MLP33 Part Number Marking Temperature Part Number Marking Temperature Si9175DH-T1 9175 --40 to 85_C Si9175DM-T1 9175 --40 to 85_C Additional voltage options are available. www.vishay.com 4 Eval Kit Temperature Range Board Si9175DB --40 to 85_C Surface Mount Document Number: 71728 S-21823—Rev. A, 07-Oct-02 Si9175 Vishay Siliconix New Product FUNCTIONAL BLOCK DIAGRAM VDD VIN Si9175 PMOS Current Sense Error Amplifier FB -+ REF Clamp PWM Comparator -+ PWM and Pulse Skipping Logic LX To IC Bias Voltage Reference UVLO ÷6 AGND SYNC 2 MHz Oscillator MODE SD PGND DETAIL DESCRIPTION General The Si9175 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. The major blocks of the Si9175 are shown in the Functional Block Diagram. The 0.25-Ω 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 <30 ms. Sensing of the inductor current for control is accomplished internally without power wasting resistors. The switching frequency can be synchronized to an external 13-MHz clock signal. accomplished in PWM mode to ensure start-up under all load conditions. Switching to other modes of operation occurs according to the state of the MODE pin and the load current. The start-up sequence occurs after SD switches from LOW to HIGH with VIN applied, or after VIN rises above the UVLO threshold and SD is a logic HIGH. Mode Control (MODE) The MODE pin allows the user to control the mode of operation or to enable the Si9175 to automatically optimize the mode of operation according to load current. There are three different modes of operation as controlled by the MODE pin. Switching waveforms are shown in the Typical Switching Waveform sections, page 9. Start-Up PWM Mode (MODE pin = HIGH) When voltage is applied to VIN and VDD, the under-voltage lockout (UVLO) circuit prevents the oscillator and control circuitry from turning on until the voltage on the exceeds 2.4 V. With a typical UVLO hysteresis of 0.1 V, the converter operates continuously until the voltage on VIN drops below 2.3 V, whereupon the converter shuts down. This hysteresis prevents false start-stop cycling as the input voltage approaches the UVLO switching threshold. Start-up is always With the MODE pin in the logic HIGH condition, the Si9175 operates as a 2-MHz fixed frequency voltage mode converter. A NMOS synchronous rectification MOSFET transistor provides very high conversion efficiency for large load currents by minimizing the conduction losses. PWM mode provides low output ripple, fast transient response, and switching frequency synchronization. Output load currents can range from 0 to 600 mA. Document Number: 71728 S-21823—Rev. A, 07-Oct-02 www.vishay.com 5 Si9175 Vishay Siliconix New Product The error amplifier and comparator control the duty cycle of the PMOS MOSFET to continuously force the REF pin and FB pin voltages to be equal. As the input-to-output voltage difference drops, the duty cycle of the PMOS MOSFET can reach 100% to allow system designers to extract the maximum stored energy from the battery. The dropout voltage is 190 mV at 600 mA. During each cycle, the PMOS switch current is limited to a maximum of 1.5 A (typical) thereby protecting the IC while continuing to force maximum current into the load. Pulse Skipping Mode (MODE pin = OPEN) By leaving the MODE pin open-circuit, the converter runs in pulse skipping mode (PSM). In PSM mode the oscillator continues to operate, but switching only occurs if the FB pin voltage is below the REF voltage at the start of each clock cycle. Clock cycles are skipped thereby reducing the switching frequency to well below 100 kHz and minimizing switching losses for improved efficiency at loads under 150 mA. Although PSM mode switching frequency varies with line and load conditions, the minimum PSM frequency will be kept above 20 kHz for load currents of 30 mA or more to prevent switching noise from reaching the audio frequency range. Each time the PMOS switch is turned on, the inductor current is allowed to reach 300 mA. Once achieved, the PMOS switch is turned off and the NMOS switch is turned on in the normal manner. However, unlike PWM mode, the NMOS switch, turns off as the switch current approaches zero current to maximize efficiency. The PMOS switch remains on continuously (100% duty cycle) when the input-voltage-to-output-voltage difference is low enabling maximum possible energy extraction from the battery. nominal. There is hysteresis in the switchover threshold to provide smooth operation. Thus, the mode PSM-to-PWM mode switchover current for increasing load currents is higher than that of PWM-to-PSM mode switchover for decreasing load currents. Oscillator Synchronization (SYNC) The internal oscillator provides for a fixed 2-MHz switching frequency. In order to minimize system noise, the oscillator of the Si9175 can be synchronized to an external clock, typically an ac-coupled 13-MHz sine wave. An on-chip divide-by-six circuit sets the converter switching frequency to 2.167 MHz in this mode. The frequency lock range of the synchronization circuitry is typically 20%. If synchronization is not required, the SYNC pin must be tied to GND permitting the internal oscillator to oscillate at 2 MHz. Dynamic Output Voltage Control (REF) The Si9175 is designed with an adjustable output voltage which has a change of VFB to VIN -- VDROP. VOUT is defined according to the following relationship: VOUT = 1 + R1 × VFB R2 Converter Shutdown (SD pin) PSM mode is recommend for load currents of 150 mA or less. With logic LOW level on the SD pin, the Si9175 is shutdown. Shutdown reduces current consumption to less than 2-mA by shutting off all of the internal circuits. Both the PMOS and NMOS transistors are turned off. A logic HIGH enables the IC to start up as described in “Start-up” section. Auto Mode Thermal Shutdown When the MODE pin grounded, the converter is set to Auto mode. Switching between PWM mode and PSM modes takes place automatically without an external control signal. For heavy load operation, the converter will operate in PWM mode to achieve maximum efficiency. When delivering light load currents, the converter operates in PSM mode to conserve power. The switchover threshold between the two modes is determined by the peak inductor current, which is 300 mA The Si9175 includes thermal shutdown circuitry, which turns off the regulator when the junction temperature exceeds 165_C. Once the junction temperature drops below 145_C, the regulator is enabled. If the condition causing the over temperature, the Si9175 begins thermal cycling, turning the regulator on and off in response to junction temperature. Restart from a thermal shutdown condition is the same as described in the “Start-up” section. www.vishay.com 6 Document Number: 71728 S-21823—Rev. A, 07-Oct-02 Si9175 Vishay Siliconix New Product APPLICATIONS CIRCUIT BATT CIN 10 mF VIN 2.2 mH VDD C1 C2 VOUT LX COUT 4.7 mF Si9175 R1 PGND 13 MHz SYNC FB ENABLE PWM/PSM/AUTO SD REF MODE REF AGND R2 CIN = 10 mF, Ceramic, Murata GRM42-2X5R106K16 C1, C2 = 0.01 mF, Vishay VJ0603Y 104KXXAT COUT = 4.7 mF, Ceramic, Murata GRM42-6X5R475K16 R1 = 8.2 kΩ, Vishay CRCW06031132F R2 = 20 kΩ, Vishay CRCW06032002F L = 2.2 mH, Toko A914BYW-2R2M TYPICAL CHARACTERISTICS VSDH VSDL SD tr tf Undefined (Load Dependent) ten VOUT Time d Indicates VOUT settles to ±2% of the final value. Figure 1. Document Number: 71728 S-21823—Rev. A, 07-Oct-02 PWM Mode VOUT Settling www.vishay.com 7 Si9175 Vishay Siliconix New Product TYPICAL CHARACTERISTICS Dropout Voltage vs. ILOAD Auto Mode Efficiency vs. Load 100 200 VIN = 3.6 V VOUT = 3.0 V Dropout Voltage (mV) Efficiency (%) 95 90 VOUT = 1.9 V 85 80 160 VIN = 2.6 V VIN = 3.6 V 120 80 VIN = 5.5 V 40 75 0 70 0 100 200 300 400 500 0 600 100 200 300 400 500 600 Load Current (mA) Load Current (mA) PSM vs. PWM Efficiency PWM 95 90 100 VIN = 3.6 V VOUT = 1.9 V COUT = 4.7 mF 85 80 75 0 100 200 300 400 500 600 Load Current (mA) Auto Mode Efficiency vs. Load Direction 100 Efficiency (%) VOUT Ripple PSM VOUT Ripple (mVp-p) Efficiency (%) 100 PSM 80 60 40 Load Decreasing 95 20 Load Increasing 90 PWM 85 0 80 0 75 0 100 200 300 400 500 600 30 60 90 120 150 Load Current (mA) Load Current (mA) www.vishay.com 8 Document Number: 71728 S-21823—Rev. A, 07-Oct-02 Si9175 Vishay Siliconix New Product TYPICAL SWITCHING WAVEFORMS (VIN = 3.6 V, VOUT = 3.0 V) PWM mode Heavy-Load Switching Waveforms, IOUT = 600 mA, MODE = HIGH PWM Mode Medium-Load Switching Waveforms, IOUT = 300 mA, MODE = HIGH VLX, 5 V/div VLX, 2 V/div Inductor Current 500 mA/div Inductor Current 500 mA/div VOUT (AC-Coupled) 10 mV/div VOUT (AC-Coupled) 10 mV/div 200 nS/div 200 nS/div PWM Mode Light-Load Switching Waveforms, IOUT = 0 mA, MODE = HIGH PSM Mode Light-Load Switching Waveforms, IOUT = 150 mA, MODE = OPEN VLX, 5 V/div VLX, 5 V/div Inductor Current 200 mA/div Inductor Current 200 mA/div VOUT (AC-Coupled) 10 mV/div VOUT (AC-Coupled) 10 mV/div 1.0 mS/div 200 nS/div PSM Mode Light-Load Switching Waveforms, IOUT = 30 mA, MODE = OPEN VLX, 5 V/div Inductor Current 200 mA/div VOUT (AC-Coupled) 100 mV/div 2.0 mS/div Document Number: 71728 S-21823—Rev. A, 07-Oct-02 www.vishay.com 9 Si9175 Vishay Siliconix New Product TYPICAL WAVEFORMS (VIN = 3.6 V, VOUT = 1.9 V) PWM Mode Heavy-Load Switching Waveforms, IOUT = 600 mA, MODE = HIGH PWM Mode Medium-Load Switching Waveforms, IOUT = 300 mA, MODE = HIGH VLX, 5 V/div VLX, 5 V/div Inductor Current 500 mA/div Inductor Current 500 mA/div VOUT (AC-Coupled) 10 mV/div VOUT (AC-Coupled) 10 mV/div 200 nS/div 200 nS/div PWM Mode Light-Load Switching Waveforms, IOUT = 0 mA, MODE = HIGH PSM Mode Light-Load Switching Waveforms, IOUT = 150 mA, MODE = OPEN VLX, 5 V/div VLX, 5 V/div Inductor Current 200 mA/div Inductor Current 200 mA/div VOUT (AC-Coupled) 10 mV/div 200 nS/div VOUT (AC-Coupled) 100 mV/div 1.0 mS/div PSM Mode Light-Load Switching Waveforms, IOUT = 30 mA, MODE = OPEN VLX, 5 V/div Inductor Current 200 mA/div VOUT (AC-Coupled) 100 mV/div 2.0 mS/div www.vishay.com 10 Document Number: 71728 S-21823—Rev. A, 07-Oct-02 Si9175 Vishay Siliconix New Product TYPICAL START-UP AND SHUTDOWN TRANSIENT WAVEFORMS (VIN = 3.6 V, VOUT = 1.9 V) Start-Up, RLOAD = 4 Ω Start-Up, VIN = VSD = 3.6 V, RLOAD = 4 Ω VIN, VSD, 1 V/div VSD, 1 V/div VOUT, 500 mV/div VOUT, 500 mV/div 20 mS/div 20 mS/div Shutdown, RLOAD = 4 Ω Enable Switching, RLOAD = 4 Ω VSD, 1 V/div VSD 1 V/div VOUT, 500 mV/div VOUT, 500 mV/div 200 mS/div 20 mS/div TYPICAL MODE SWITCH TRANSIENT WAVEFORM Output Transient At Mode Switch, ILOAD = 30 mA VOUT (AC-Coupled) 200 mV/div Mode Pin 1 V/div 100 mS/div Document Number: 71728 S-21823—Rev. A, 07-Oct-02 www.vishay.com 11 Si9175 Vishay Siliconix New Product TYPICAL LOAD TRANSIENT WAVEFORMS (VIN = 3.6 V, VOUT = 1.9 V) Load Transient, Auto Mode, ILOAD = 30 to 500 mA, MODE = LOW Load Transient, PWM Mode, ILOAD = 30 to 500 mA, L = 2.2 mH, MODE= HIGH ILOAD, 200 mA /div ILOAD, 200 mA /div VOUT (AC-Coupled) 50 V/div VOUT (AC-Coupled) 50 mV/div 10 mS/div 10 mS/div Load Transient (PSM Mode), ILOAD = 30 to 150 mA, L = 2.2 mH ILOAD, 200 mA /div VOUT (AC-Coupled) 50 mV/div 100 mS/div www.vishay.com 12 Document Number: 71728 S-21823—Rev. A, 07-Oct-02