RT9266B Preliminary Tiny Package, High Efficiency, Step-up DC/DC Converter General Description The RT9266B is a compact, high efficiency, and low voltage step-up DC/DC converter with an Adaptive Current Mode PWM control loop, includes an error amplifier, ramp generator, comparator, switch pass element and driver in which providing a stable and high efficient operation over a wide range of load currents. It operates in stable waveforms without external compensation. The low start-up input voltage below 1V makes RT9266B suitable for 1 to 4 battery cells applications with a 500mA internal switch. The 550kHz high switching rate minimized the size of external components. Besides, the 25µA low quiescent current together with high efficiency maintains long battery lifetime. Ordering Information RT9266B Package Type E : SOT-26 Operating Temperature Range C: Commercial Standard Marking Information Features 1.0V Low Start-up Input Voltage at 1mA Load 25µA Quiescent (Switch-off) Supply Current Zero Shutdown Mode Supply Current 90% Efficiency 550kHz Switching Frequency at 3.3V VDD Providing Flexibility for Using Internal and External Power Switches Small SOT-26 Package Applications PDA DSC LCD Panel RF-Tags MP3 Portable Instrument Wireless Equipment Pin Configurations Part Number RT9266BCE (Plastic SOT-26) Pin Configurations TOP VIEW 6 5 4 1 2 3 1. 2. 3. 4. 5. 6. CE EXT GND LX VDD FB For marking information, contact our sales representative directly or through a RichTek distributor located in your area, otherwise visit our website for detail. DS9266B-00 May 2003 www.richtek.com 1 RT9266B Preliminary Typical Application Circuit L1 VIN D1 3.3 to 10 uH C3 10uF SS0520 VOUT 3.3V/5V C2 1uF R1 1.6M/3M VDD CE RT9266B EXT LX FB GND R2 980K/1M C1 10uF Fig. 1 RT9266B Typical Application for Portable Instruments L1 VIN D1 3.3 to 10 uH C3 10uF VOUT 3.3V/5V SS0520 C2 1uF VDD CE LX RT9266B EXT GND Q1 N MOS R1 1.6M/3M C1 10uF FB R2 980K/1M Fig. 2 RT9266B for Higher Current Applications Pin Description Pin Name Pin Function CE Chip enable RT9266B gets into shutdown mode when CE pin set to low. EXT Output pin for driving external NMOS GND Ground LX Pin for switching VDD Input positive power pin of RT9266B FB Feedback input pin Internal reference voltage for the error amplifier is 1.25V. www.richtek.com 2 DS9266B-00 May 2003 RT9266B Preliminary Function Block Diagram EXT RT9266B VCC LX1 + FB 1.25V Q1 N MOS Loop Control Circuit VDD R1 R2 Shut Down Q3 N MOS CE Over Temp. Detector GND Test Circuit I (VIN) A L1 D1 10uH + VIN C3 10uF A I (VDD) VDD CE RT9266B LX EXT GND FB SS0520 VOUT 3.3V/5V C2 1uF R1 1.6M/3M C4 100p C5 10uF R2 980K/1M DS9266B-00 May 2003 www.richtek.com 3 RT9266B Preliminary Absolute Maximum Ratings − 0.3V to 7V − 0.3V to (VDD + 0.8V) − 0.3V to (VDD + 0.3V) 2.5A 200mA Supply Voltage LX Pin Switch Voltage Other I/O Pin Voltages LX Pin Switch Current EXT Pin Driver Current • Package Thermal Resistance SOT-26, θJC Operating Junction Temperature Storage Temperature Range 145°C/W 125°C − 65°C ~ +150°C Electrical Characteristics (VIN = 1.5V, VDD set to 3.3V, Load Current = 0, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Units Start-UP Voltage VST IL = 1mA -- 0.98 1.05 V Operating VDD Range VDD VDD pin voltage 2 -- 6.5 V No Load Current I (VIN) INO LOAD VIN = 1.5V, VOUT = 3.3V -- 150 -- µA Switch-off Current I (VDD) ISWITCH OFF VIN = 6V -- 25 -- µA Shutdown Current I (VIN) IOFF CE Pin = 0V, VIN = 4.5V -- 0.01 1 µA Feedback Reference Voltage VREF Close Loop, VDD = 3.3V 1.225 1.25 1.275 V Switching Frequency FS VDD = 3.3V -- 550 -- kHz Maximum Duty DMAX VDD = 3.3V -- 95 -- % VDD = 3.3V -- 0.35 -- Ω VDD = 3.3V -- 0.5 -- A Current Limit Delay Time VDD = 3.3V -- 300 -- nS EXT ON Resistance to VDD VDD = 3.3V -- 5 -- Ω EXT ON Resistance to GND VDD = 3.3V -- 5 -- Ω LX ON Resistance Current Limit Setting ILIMIT Line Regulation (refer to VFB) ∆VLINE VIN = 1.5 ~ 2.5V, IL = 50mA -- 12 -- mV/V Load Regulation (refer to VFB) ∆VLOAD VIN = 2.5V, IL = 1 ~ 100mA -- 0.25 -- mV/mA 0.4 0.8 1.2 V CE Pin Trip Level VDD = 3.3V Temperature Stability for Vout Ts -- 50 -- ppm/°C Thermal Shutdown TSD -- 165 -- °C Thermal Shutdown Hysterises ∆TSD -- 10 -- °C www.richtek.com 4 DS9266B-00 May 2003 RT9266B Preliminary Typical Operating Characteristics Efficiency vs. Output Current Efficiency vs. Output Current 100 95 VIN = 3V VIN = 2.5V VIN = 2V 90 90 VIN = 1.5V 80 Efficiency (%) Efficiency (%) 85 VIN = 4.5V VIN = 4V VIN = 3.5V VIN = 3V VIN = 2.5V VIN = 2V VIN = 1.5V VIN = 1V 75 70 80 70 65 60 VOUT = 3.3V, TA = 25˚C 1 10 VOUT = 5V, TA = 25˚C 60 100 1 1000 10 5.1 3.32 Output Voltage (V) Output Voltage (V) 1000 Output Voltage vs. Output Current Output Voltage vs. Output Current 3.36 VIN = 3V VIN = 2.5V 3.28 VIN = 2V 3.24 VIN = 1.5V VIN = 1V 1 10 VIN = 4.5V 5.05 VIN = 4V 5 VIN = 3.5V 4.95 VIN = 3V 4.9 VOUT = 3.3V, TA = 25˚C 3.2 VOUT = 5V, TA = 25˚C 4.85 100 1 1000 10 300 700 Input Current (uA) 1 800 250 200 150 100 50 600 500 400 300 200 100 VOUT = 3.3V @ no load VOUT = 5V @ no load 0 0 2 Input Voltage (V) DS9266B-00 May 2003 2.5 1000 Input Current vs. Input Voltage Input Current vs. Input Voltage 1.5 100 Output Current (mA) 350 1 VIN = 2.5V VIN = 2V VIN = 1.5V Output Current (mA) Input Current (uA) 1 100 Output Current ( mA) Output Current (mA) 3 1 2 3 4 5 Input Voltage (V) www.richtek.com 5 RT9266B Preliminary LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 VIN = 1V, VOUT = 3.3V @ 10mA Output Ripple (mV) Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 VIN = 1V, VOUT = 3.3V @ 50mA Time (1us/Div) Time (1us/Div) LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 VIN = 1.5V, VOUT = 3.3V @ 10mA Output Ripple (mV) Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 Time (1us/Div) Time (1us/Div) LX Wave Form (V) 2 0 10 0 -10 VIN = 2V, VOUT = 3.3V @ 10mA Time (1us/Div) www.richtek.com 6 LX Pin Wave Form & Output Ripple Output Ripple (mV) Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 VIN = 1.5V, VOUT = 3.3V @ 100mA 4 2 0 10 0 -10 VIN = 2V, VOUT = 3.3V @ 100mA Time (1us/Div) DS9266B-00 May 2003 RT9266B Preliminary LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 VIN = 2.5V, VOUT = 3.3V @ 10mA Output Ripple (mV) Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 VIN = 2.5V, VOUT = 3.3V @ 100mA Time (1us/Div) Time (1us/Div) LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 VIN = 3V, VOUT = 3.3V @ 10mA Output Ripple (mV) Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 4 2 0 10 0 -10 VIN = 3V, VOUT = 3.3V @ 100mA Time (1us/Div) Time (1us/Div) LX Wave Form (V) 6 4 2 Output Ripple (mV) 0 10 0 -10 VIN = 1.5V, VOUT = 5V @ 10mA Time (1us/Div) DS9266B-00 LX Pin Wave Form & Output Ripple May 2003 Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 6 4 2 0 10 0 -10 VIN = 1.5V, VOUT = 5V @ 80mA Time (1us/Div) www.richtek.com 7 RT9266B Preliminary LX Wave Form (V) LX Pin Wave Form & Output Ripple 6 4 2 0 6 4 2 0 10 0 -10 VIN = 2V, VOUT = 5V @ 10mA Output Ripple (mV) Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 10 0 -10 VIN = 2V, VOUT = 5V @ 100mA Time (1us/Div) Time (1us/Div) LX Pin Wave Form & Output Ripple LX Wave Form (V) LX Wave Form (V) LX Pin Wave Form & Output Ripple 6 4 2 4 2 0 10 0 -10 VIN = 2.5V, VOUT = 5V @ 10mA Output Ripple (mV) 0 Output Ripple (mV) 6 10 0 -10 VIN = 2.5V, VOUT = 5V @ 100mA Time (1us/Div) Time (1us/Div) LX Wave Form (V) 6 4 2 Output Ripple (mV) 0 10 0 -10 VIN = 3V, VOUT = 5V @ 10mA Time (1us/Div) www.richtek.com 8 LX Pin Wave Form & Output Ripple Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 6 4 2 0 10 0 -10 VIN = 3V, VOUT = 5V @ 100mA Time (1us/Div) DS9266B-00 May 2003 RT9266B Preliminary LX Pin Wave Form & Output Ripple LX Wave Form (V) LX Wave Form (V) LX Pin Wave Form & Output Ripple 6 4 2 10 0 -10 VIN = 3.5V, VOUT = 5V @ 10mA Output Ripple (mV) Output Ripple (mV) 0 6 4 2 0 10 0 -10 VIN = 3.5V, VOUT = 5V @ 100mA Time (1us/Div) Time (1us/Div) LX Pin Wave Form & Output Ripple LX Wave Form (V) LX Wave Form (V) LX Pin Wave Form & Output Ripple 6 4 2 10 0 -10 VIN = 4V, VOUT = 5V @ 10mA Output Ripple (mV) Output Ripple (mV) 0 6 4 2 0 10 0 -10 VIN = 4V, VOUT = 5V @ 100mA Time (2.5us/Div) Time (1us/Div) LX Wave Form (V) LX Pin Wave Form & Output Ripple 6 4 2 0 10 0 -10 VIN = 4.5V, VOUT = 5V @ 10mA Time (5us/Div) DS9266B-00 6 4 2 0 May 2003 Output Ripple (mV) Output Ripple (mV) LX Wave Form (V) LX Pin Wave Form & Output Ripple 10 0 -10 VIN = 4.5V, VOUT = 5V @ 100mA Time (1us/Div) www.richtek.com 9 RT9266B Preliminary Load Transient Respones 0 -20 Output Current (mA) 0 -50 ≈ ≈ 50 0 Time (2.5ms/Div) Load Transient Respones Load Transient Respones VIN = 3V, VOUT = 3.3V IOUT = 10mA to 100mA 0 -20 ≈ Output Current (mA) ≈ 50 0 VIN = 3V, VOUT = 5V IOUT = 10mA to 100mA 100 0 -100 ≈ ≈ 100 50 0 Time (2.5ms/Div) Time (2.5ms/Div) Load Transient Respones Load Transient Respones VIN = 3.5V, VOUT = 5V IOUT = 10mA to 100mA 100 0 -100 ≈ ≈ Output Current (mA) Output Voltage (mV) Output Current (mA) 0 Time (2.5ms/Div) 100 100 50 0 Time (2.5ms/Div) www.richtek.com 10 VIN = 1.5V, VOUT = 3.3V IOUT = 10mA to 100mA 50 100 20 Output Voltage (mV) Output Current (mA) 40 20 Output Current (mA) Output Voltage (mV) ≈ ≈ Output Voltage (mV) Output Voltage (mV) VIN = 1V, VOUT = 3.3V IOUT = 10mA to 50mA 20 Output Voltage (mV) Load Transient Respones VIN = 4.2V, VOUT = 5V IOUT = 10mA to 100mA 100 0 -100 ≈ ≈ 100 50 0 Time (2.5ms/Div) DS9266B-00 May 2003 Preliminary RT9266B Switching Frequency vs. VDD Pin Voltage Switching Frequency (kHz)1 700 600 500 400 300 VDD = CE FB = GND TA = 25˚C 200 100 0 1 2 3 4 5 6 VDD Pin Voltage (V) DS9266B-00 May 2003 www.richtek.com 11 RT9266B Preliminary Application Note Output Voltage Setting Referring to application circuits, the output voltage of the switching regulator (VOUT) can be set with Eq.1. VOUT1 = (1 + R1 ) × 1.25 V R2 Eq.1 Feedback Loop Design Referring to application circuits, The selection of R1 and R2 based on the trade-off between quiescent current consumption and interference immunity is stated below: • Follow Eq.1 • Higher R reduces the quiescent current (Path current = 1.25V/R2), however resistors beyond 5MΩ are not recommended. • Lower R gives better noise immunity, and is less sensitive to interference, layout parasitics, FB node leakage, and improper probing to FB pins. Layout Guide • A full GND plane without gap break. • VDD to GND noise bypass – Short and wide connection for the 1µF MLCC capacitor between Pin5 and Pin3. • VIN to GND noise bypass – Add a capacitor close to L1 inductor, when VIN is not an idea voltage source. • Minimized FB node copper area and keep far away from noise sources. • Minimized parasitic capacitance connecting to LX and EXT nodes, which may cause additional switching loss. Board Layout Example (2-Layer Board) (Refer to Application Circuit Fig. 2 for the board) VOUT1 Prober Parasitics R1 _ Q + R2 FB Pin • A proper value of feed forward capacitor parallel with R1 can improve the noise immunity of the feedback loops, especially in an improper layout. An empirical suggestion is around 0~33pF for feedback resistors of MΩ, and 10nF~0.1µF for feedback resistors of tens to hundreds kΩ. - Top Layer – For applications without standby or suspend modes, lower values of R1 and R2 are preferred. For applications concerning the current consumption in standby or suspend modes, the higher values of R1 and R2 are needed. Such “high impedance feedback loops” are sensitive to any interference, which require careful layout and avoid any interference, e.g. probing to FB pin. - Bottom Layer www.richtek.com 12 DS9266B-00 May 2003 RT9266B Preliminary Package Information H D L C B 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 -- 0.152 -- 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 0.102 0.254 0.004 0.010 L 0.356 0.610 0.014 0.024 SOT- 26 Surface Mount Package DS9266B-00 May 2003 www.richtek.com 13 RT9266B Preliminary 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] www.richtek.com 14 DS9266B-00 May 2003