RT8008 Preliminary 1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter General Description Features The RT8008 is a high-efficiency pulse-width-modulated (PWM) step-down DC-DC converter. Capable of delivering 600mA output current over a wide input voltage range from 2.2 to 5.5V, the RT8008 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy-terminals. Two operational modes are available: PSM/PWM/ Low-Dropout autoswitch and shut-down modes. Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky diode is required in practical application. The RT8008 automatically turns off the synchronous rectifier while the inductor current is low and enters discontinuous PWM mode. This can increase efficiency at light load condition. The RT8008 enters PSM (Pulse-Skipping Mode) at extremely light load condition. The equivalent switching frequency is reduced to increase the efficiency in PSM. The RT8008 enters Low-Dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. RT8008 enter shutdown mode and consumes less than 0.1uA when EN pin is pulled low. +2.2V to +5.5V Input Range Adjustable Output From 0.6V to VIN 1.0V, 1.2V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/ Adjustable Output Voltage 600mA Output Current 95% Efficiency No Schottky Diode Required 50uA Quiescent Current 1.5MHz Fixed-Frequency PWM Operation Pulse-skipping Mode Operation During Light Ioad Small SOT-23-5 and TSOT-23-5 Package RoHS Compliant and 100% Lead (Pb)-Free Applications Cellular Telephones Personal Information Appliances Wireless and DSL Modems MP3 Players Portable Instruments Ordering Information RT8008(- Package Type B : SOT-23-5 J5 : TSOT-23-5 Operating Temperature Range C : Commercial Standard P : Pb Free with Commercial Standard The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 1.5MHz. This along with small SOT-23-5 and TSOT-23-5 package provides small PCB area application. Other features include soft start, lower internal reference voltage with 2% accuracy, over temperature protection, and over current protection. Output Voltage Default : Adjustable 10 : 1.0V 12 : 1.2V 15 : 1.5V 18 : 1.8V 25 : 2.5V 33 : 3.3V Pin Configurations (TOP VIEW) EN 1 GND 2 LX 3 5 FB/VOUT ) Note : RichTek Pb-free products are : `RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. 4 VIN SOT-23-5/TSOT-23-5 DS8008-00 December 2005 `Suitable for use in SnPb or Pb-free soldering processes. `100% matte tin (Sn) plating. www.richtek.com 1 RT8008 Preliminary Typical Application Circuit 4 VIN 2.2V to 5.5V VIN CIN 4.7uF LX 3 L 2.2uH VOUT RT8008 1 EN VOUT COUT 5 10uF GND 2 Figure 1. Fixed Voltage Regulator VIN 2.2V to 5.5V 4 CIN VIN LX VOUT C1 RT8008 4.7uF 1 EN FB GND 2 R1 ⎞ ⎛ V OUT = V REF x ⎜ 1 + ⎟ R2 ⎝ ⎠ 3 L 2.2uH R1 COUT 5 10uF IR2 R2 with R2 = 300kΩ to 60kΩ so the IR2 = 2μA to 10μA, and (R1 x C1) should be in the range between 3x10-6 and 6x10-6ΩF for component selection. Figure 2. Adjustable Voltage Regulator Functional Pin Description Pin Number Pin Name Pin Function 1 EN Chip Enable (Active High) 2 GND Ground 3 LX Pin for Switching 4 VIN Power Input 5 FB/VOUT Feedback Input Pin www.richtek.com 2 DS8008-00 December 2005 RT8008 Preliminary Function Block Diagram VIN EN RS1 OSC & Shutdown Control Slope Compensation FB/VOUT Error Amplifier Current Limit Detector PSM/PWM Mode Detector Current Sense Control Logic PWM Comparator Driver LX RC COMP UVLO & Power Good Detector Zero Detector RS2 VREF GND DS8008-00 December 2005 www.richtek.com 3 RT8008 Preliminary Absolute Maximum Ratings (Note 1) Supply Input Voltage -----------------------------------------------------------------------------------------------------Enable, FB Voltage ------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOT-23-5, TSOT-23-5 ----------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 4) SOT-23-5, TSOT-23-5, θJA ----------------------------------------------------------------------------------------------SOT-23-5, TSOT-23-5, θJC ----------------------------------------------------------------------------------------------Junction Temperature Range -------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 2) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------------------ Recommended Operating Conditions 6.5V VIN + 0.6V 0.4W 250°C/W 130°C/W 150°C 260°C −65°C to 150°C 2kV 200V (Note 3) Supply Input Voltage ------------------------------------------------------------------------------------------------------ 2.2V to 5.5V Operating Ambient Temperature Range ------------------------------------------------------------------------------ −40°C to 85°C Operating Junction Temperature Range ------------------------------------------------------------------------------ −40°C to 125°C Electrical Characteristics (VIN = 3.6V, VOUT = 2.5V, VREF = 0.6V, L = 2.2μH, CIN = 4.7μF, COUT = 10μF, TA = 25°C, IMAX = 600mA unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Units 2.2 -- 5.5 V Input Voltage Range VIN Quiescent Current IQ IOUT = 0mA, VFB = VREF + 5% -- 50 100 μA Shutdown Current IQ(SD) EN = GND -- 0.1 1 μA Reference Voltage VREF For adjustable output voltage 0.588 0.6 0.612 V Adjustable Output Range VOUT VREF -- VIN V Output Voltage Accuracy FB Input Current ΔVOUT VIN = 2.2 to 5.5V, VOUT = 1.0V 0mA < IOUT < 600mA -3 -- +3 % ΔVOUT VIN = 2.2 to 5.5V, VOUT = 1.2V 0mA < IOUT < 600mA -3 -- +3 % ΔVOUT VIN = 2.2 to 5.5V, VOUT = 1.5V 0mA < IOUT < 600mA -3 -- +3 % ΔVOUT VIN = 2.2 to 5.5V, VOUT = 1.8V 0mA < IOUT < 600mA -3 -- +3 % ΔVOUT VIN = 2.8 to 5.5V, VOUT = 2.5V 0mA < IOUT < 600mA -3 -- +3 % ΔVOUT VIN = 3.5 to 5.5V, VOUT = 3.3V 0mA < IOUT < 600mA -3 -- +3 % ΔVOUT VIN = VOUT + 0.2V to 5.5V 0mA < IOUT < 600mA -3 -- +3 % IFB VFB = VIN -50 -- 50 nA To be continued www.richtek.com 4 DS8008-00 December 2005 RT8008 Preliminary Parameter Symbol Test Conditions Min Typ Max VIN = 3.6V -- 0.35 -- VIN = 2.5V -- 0.45 -- VIN = 3.6V -- 0.30 -- VIN = 2.5V -- 0.40 -- Units Ω PMOSFET RON PRDS(ON) IOUT = 200mA NMOSFET RON NRDS(ON) IOUT = 200mA P-Channel Current Limit IP(LM) VIN = 2.2 to 5.5 V 0.8 -- 1.8 A EN High-Level Input Voltage VENH VIN = 2.2V to 5.5V 1.5 -- -- V EN Low-Level Input Voltage VENL VIN = 2.2V to 5.5V -- -- 0.4 V Undervoltage Lock Out threshold -- 1.8 -- V Hysteresis -- 0.1 -- V 1.2 1.5 1.8 MHz -- 160 -- °C -- 50 -- ns 100 -- -- % -1 -- 1 μA Oscillator Frequency fOSC Thermal Shutdown Temperature TSD VIN = 3.6V, IOUT = 100mA Min. On Time Max. Duty Cycle LX Leakage Current VIN = 3.6V, VLX = 0V or VLX = 3.6V Ω Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. 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 remain possibility to affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Pin 2 of SOT-23-5/TSOT-23-5 packages is the case position for θJC measurement. DS8008-00 December 2005 www.richtek.com 5 RT8008 Preliminary Typical Operating Characteristics Efficiency vs. Input Voltage Efficiency vs. Output Current 100 100% 100 100% VOUT = 1.8V 90 90% 95 95% 80 80% Efficiency (%) Efficiency (%) 70 70% IOUT = 150mA 90 90% VOUT = 1.2V 60 60% 50 50% 40 40% 30 30% IOUT = 300mA 85 85% 80 80% 75 75% IOUT = 1mA 70% 70 20 20% 65% 65 10 10% VOUT = 1.2V VIN = 3.3V 0%0 60% 60 0.1 1 10 100 1000 2.5 3 4.5 5 5.5 Switching Frequency vs. Temperature Quiescent Current vs. Input Voltage 1.7 Switching Frequency (MHz) 55 53 51 49 47 1.65 1.6 1.55 1.5 1.45 1.4 1.35 VIN = 3.3V, IOUT = 300mA TA = 25°C 1.3 45 2.5 3 3.5 4 4.5 5 -40 -30 -20 -10 5.5 0 10 20 30 40 50 60 70 80 Temperature (°C) Input Voltage(V) Output Voltage vs. Output Current Output Voltage vs. Output Current 1.25 1.84 1.24 1.83 1.82 Output Voltage (V) 1.23 Output Voltage (V) 4 Input Voltage (V) Output Current (mA) Quiescent Current (uA) 3.5 1.22 1.21 1.2 1.19 1.18 1.17 1.81 1.8 1.79 1.78 1.77 1.76 1.75 1.74 1.16 VIN = 3.3V 1.15 1.73 VIN = 3.3V 1.72 0 50 100 150 200 250 300 350 400 450 500 550 600 Output Current (mA) www.richtek.com 6 0 50 100 150 200 250 300 350 400 450 500 550 600 Output Current (mA) DS8008-00 December 2005 Preliminary I LOAD (500mA/Div) Load Transient Response Load Transient Response VIN = 5V, VOUT = 1.2V, IOUT = 300mA to 50mA VOUT (50mV/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 600mA to 300mA I LOAD (500mA/Div) I LOAD (500mA/Div) Time (250μs/Div) Time (250μs/Div) Load Transient Response Load Transient Response VIN = 5V, VOUT = 1.2V, IOUT = 600mA to 300mA I LOAD (500mA/Div) VIN = 5V, VOUT = 1.2V, IOUT = 600mA to 50mA VOUT (100mV/Div) VOUT (100mV/Div) Time (250μs/Div) I LOAD (500mA/Div) VOUT (100mV/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 600mA to 50mA Time (250μs/Div) Time (250μs/Div) DS8008-00 Load Transient Response VOUT (100mV/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 300mA to 50mA I LOAD (500mA/Div) VOUT (100mV/Div) Load Transient Response RT8008 December 2005 Time (250μs/Div) www.richtek.com 7 RT8008 Preliminary VOUT EN (1V/Div) (2V/Div) Start-Up VIN = 2.2V, VOUT = 1.2V, IOUT = 600mA Time (1ms/Div) ILX (500mA/Div) ILX (500mA/Div) VOUT EN (1V/Div) (2V/Div) Start-Up VIN = 3.3V, VOUT = 1.2V, IOUT = 600mA Time (1ms/Div) ILX (500mA/Div) VOUT EN (1V/Div) (5V/Div) Start-Up VIN = 5V, VOUT = 1.2V, IOUT = 600mA Time (1ms/Div) www.richtek.com 8 DS8008-00 December 2005 Preliminary Applications Information RT8008 The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings airflow and temperature difference between junction to ambient. The maximum power dissipation can be calculated by following formula : The value of junction to case thermal resistance θJC is popular for users. This thermal parameter is convenient for users to estimate the internal junction operated temperature of packages while IC operating. It's independent of PCB layout, the surroundings airflow effects and temperature difference between junction to ambient. The operated junction temperature can be calculated by following formula : PD(MAX) = ( TJ(MAX) - TA ) / θJA TJ = TC + PD x θJC Where T J(MAX) is the maximum operation junction temperature 125°C, TA is the ambient temperature and the θJA is the junction to ambient thermal resistance. Where TC is the package case (Pin 2 of package leads) temperature measured by thermal sensor, PD is the power dissipation defined by user's function and the θJC is the junction to case thermal resistance provided by IC manufacturer. Therefore it's easy to estimate the junction temperature by any condition. Thermal Considerations For recommended operating conditions specification of RT8008 DC/DC converter, where TJ (MAX) is the maximum junction temperature of the die (125°C) and TA is the maximum ambient temperature. The junction to ambient thermal resistance θ JA is layout dependent. For SOT-23-5/TSOT-23-5 packages, the thermal resistance θJA is 250° C/W on the standard JEDEC 51-3 single-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by following formula : PD(MAX) = ( 125°C - 25°C ) / 250 = 0.4 W for SOT-23-5/ TSOT-23-5 packages The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance θJA. For RT8008 packages, the Figure 1 of derating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. Maximum Power Dissipation (mW) 450 Single Layer PCB 400 350 SOT-23-5, TSOT-23-5 Packages 300 250 200 150 100 50 0 0 20 40 60 80 100 120 140 Ambient Temperature (°C) Figure 1. Derating Curves for RT8008 Package DS8008-00 December 2005 www.richtek.com 9 RT8008 Preliminary Outline Dimension H D L B C b A A1 e Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.889 1.295 0.035 0.051 A1 0.000 0.152 0.000 0.006 B 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 C 2.591 2.997 0.102 0.118 D 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 H 0.080 0.254 0.003 0.010 L 0.300 0.610 0.012 0.024 SOT-23-5 Surface Mount Package www.richtek.com 10 DS8008-00 December 2005 RT8008 Preliminary H D L B C b A A1 e Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.700 1.000 0.028 0.039 A1 0.000 0.100 0.000 0.004 B 1.397 1.803 0.055 0.071 b 0.300 0.559 0.012 0.022 C 2.591 3.000 0.102 0.118 D 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 H 0.080 0.254 0.003 0.010 L 0.300 0.610 0.012 0.024 TSOT-23-5 Surface Mount Package RICHTEK TECHNOLOGY CORP. RICHTEK TECHNOLOGY CORP. Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)89191466 Fax: (8862)89191465 Email: [email protected] DS8008-00 December 2005 www.richtek.com 11