RT9266 Tiny Package, High Efficiency, Step-up DC/DC Converter General Description Features The RT9266 is a compact, high efficiency, and low voltage l 1.0V Low Start-up Input Voltage step-up DC/DC converter with an Adaptive Current Mode l High Supply Capability to Deliver 3.3V 100mA with 1 Alkaline Cell PWM control loop, includes an error amplifier, ramp generator, comparator, switch pass element and driver l 17µA Quiescent (Switch-off) Supply Current in which providing a stable and high efficient operation l Zero Shutdown Mode Supply Current over a wide range of load currents. It operates in stable l 90% Efficiency waveforms without external compensation. The low start-up input voltage below 1V makes RT9266 l 450kHz Fixed Switching Frequency l Providing Flexibility for Using Internal and External Power Switches suitable for 1 to 4 battery cells applications of providing up to 300mA output current. The 450kHz high switching rate minimized the size of external components. Besides, the 17µA low quiescent current together with high efficiency maintains long battery lifetime. The output voltage is set with two external resistors. Both internal 2A switch and driver for driving external power devices (NMOS or NPN) are provided. Ordering Information l Small SOT-26 & SOT89-5 Package Applications l PDA l DSC l LCD Panel l RF-Tags l MP3 l Portable Instrument l Wireless Equipment RT9266 Pin Configurations Package Type E : SOT-26 X5 : SOT-89-5 Operating Temperature Range C : Commercial Standard P : Pb Free with Commercial Standard Marking Information (TOP VIEW) CE 1 6 FB EXT 2 5 VDD GND 3 4 LX For marking information, contact our sales representative SOT-26 directly or through a RichTek distributor located in your area, otherwise visit our website for detail. GND LX 5 4 1 2 3 CE VDD FB SOT-89-5 DS9266-06 June 2004 www.richtek.com 1 RT9266 Typical Application Circuit L1 + VIN D1 3.3 to 10 uH C3 100uF 1N5819 VOUT 3.3V/5V C2 1uF R1 1.6M/3M VDD RT9266 LX EXT GND FB + CE C1 100uF R2 980k/1M Figure 1. RT9266 Typical Application for Portable Instruments 3.1V to 5V for 12V 2.8V to 5V for 9V VIN L1 D1 + 4.7uH C4 100uF 1N5819 RVDD 100 CVDD 1uF CE EXT RT9266 LX GND FB Q1 N MOS 12V/9V 300mA R1 C3 0.1uF 860k/620k RM 0.22 R2 100k C2 1uF + VDD C1 100uF Figure 2. RT9266 High Voltage Applications www.richtek.com 2 DS9266-06 June 2004 RT9266 L1 + VIN D1 3.3 to 10 uH C3 100uF VOUT 3.3V/5V 1N5819 C2 1uF VDD CE LX RT9266 EXT + GND Q1 N MOS R1 1.6M/3M FB C1 100uF R2 980k/1M Figure 3. RT9266 for Higher Current Applications L1 VIN 3.3V/5V R3 100 C2 1uF 4.7uH C8 1uF C3 10uF C1 1uF Q1 CE VDD LX RT9266 FB GND N MOS C4 10uF C6 C7 1uF 0.1uF VOUT2 +18V 10mA VOUT1 +9V 10mA R1 620k EXT R2 100k C5 10uF VOUT3 -9V 10mA Figure 4. RT9266 for Multi-Output Applications DS9266-06 June 2004 www.richtek.com 3 RT9266 Functional Pin Description Pin No. Pin Name Pin Function RT9266CX5 RT9266CE 1 1 CE -- 2 EXT Output pin for driving external NMOS 5 3 GND Ground 4 4 LX Pin for switching 2 5 VDD Input positive power pin of RT9266 3 6 FB Chip enable RT9266 gets into shutdown mode when CE pin set to low. Feedback input pin Internal reference voltage for the error amplifier is 1.25V. Function Block Diagram EXT RT9266 VDD LX Q1 N MOS - FB + 1.25V Loop Control Circuit R1 VDD R2 Shut Down Q2 N MOS CE Over Temp. Detector GND Test Circuit I (VIN) A L1 D1 10uH + VIN C3 100uF I (VDD) VOUT 3.3V/5V C2 1uF + A 1N5819 R1 1.6M/3M VDD CE RT9266 LX EXT GND FB C4 102 C1 100uF C5 106 R2 980k/1M www.richtek.com 4 DS9266-06 June 2004 RT9266 Absolute Maximum Ratings l −0.3V to 7V −0.3V to 7V Other I/O Pin Voltages ----------------------------------------------------------------------------------------- −0.3V to (VDD + 0.3V) l LX Pin Switch Current ------------------------------------------------------------------------------------------ 2.5A l EXT Pin Driver Current ----------------------------------------------------------------------------------------- 200mA l Package Thermal Resistance l Supply Voltage --------------------------------------------------------------------------------------------------- l LX Pin Switch Voltage ------------------------------------------------------------------------------------------ SOT-26, θJC ------------------------------------------------------------------------------------------------------- 145 ° C/W SOT-89-5, θJC ---------------------------------------------------------------------------------------------------- 45 °C/W l Operating Junction Temperature ---------------------------------------------------------------------------- 125 °C l Storage Temperature Range ---------------------------------------------------------------------------------- −65° C to +150° C NOTE: Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under any conditions. Moreover, such values for any two items must not be reached simultaneously. Operation above these absolute maximum ratings may cause degradation or permanent damage to the device. These are stress ratings only and do not necessarily imply functional operation below these limits Electrical Characteristics (VIN = 1.5V, VDD set to 3.3V, Load Current = 0, T A = 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 V Shutdown Current I (VIN) IOFF CE Pin = 0V, VIN = 4.5V -- 0.01 1 µA Switch-off Current I (VDD) ISWITCH OFF VIN = 6V -- 17 25 µA Continuous Switching Current ISWITCH 0.4 0.55 0.7 mA -- µA VIN = CE= 3.3V, VFB = GND * No Load Current I (VIN) INO LOAD VIN = 1.5V, VOUT = 3.3V -- 75 Feedback Reference Voltage VREF Close Loop, VDD = 3.3V 1.225 1.25 1.275 V Switching Frequency FS VDD = 3.3V 425 500 575 kHz Maximum Duty DMAX VDD = 3.3V 85 95 -- % VDD = 3.3V -- 0.3 1.1 LX ON Resistance Current Limit Setting ** Ω VDD = 3.3V 1.6 2 2.6 A EXT ON Resistance to VDD VDD = 3.3V -- 5 8.5 Ω EXT ON Resistance to GND VDD = 3.3V -- 5 8.5 Ω VIN = 3.5 ~ 6V, IL = 1mA -- 1.5 10 mV/V -- mV/mA Line Regulation Load Regulation ILIMIT ∆VLINE ∆VLOAD CE Pin Trip Level VIN = 2.5V, IL = 1 ~ 100mA VDD = 3.3V -- 0.25 *** 0.4 0.8 1.2 V Temperature Stability for Vout TS -- 50 -- ppm/°C Thermal Shutdown Hysterises ∆TSD -- 10 -- °C DS9266-06 June 2004 www.richtek.com 5 RT9266 Note : * No Load Current is highly dependent on practical system design and component selection that cannot be covered by production testing. Typical No Load Current is verified by typical application circuit with recommended components. No Load Current performance is guaranteed by Switch Off Current and Continuous Switching Current. ** Current Limit is guaranteed by design at T A = 25°C. ***Load Regulation is not tested at production due to practical instrument limitation. Load Regulation performance is dominantly dependent on DC loop gain and LX ON Resistance that are guaranteed by “ Line Regulation ” and “ LX ON Resistance” tests in production. www.richtek.com 6 DS9266-06 June 2004 RT9266 Typical Operating Characteristics (Refer to Test Circuit) Efficiency vs. Output Current Efficiency vs. Output Current 95 95 VOUT = 5V, TA = 25°C VOUT = 3.3V, TA = 25°C 90 Efficiency (%) Efficiency (%) 90 VIN = 4.0V VIN = 3.5V VIN = 3.0V VIN = 2.5V VIN = 2.0V 85 80 75 VIN = 3.0V 85 VIN = 2.5V 80 VIN = 2.0V 75 VIN = 1.5V VIN = 1.5V VIN = 1.0V 70 70 000 001 010 100 0.1 1000 1 Input Current I(VDD) vs. Output Current 1000 21 VIN = 3V, VOUT = 5V VOUT = 5V @ no load 20 Input Current ( µ A) 200 Input Current ( µ A) 100 Input Current I(VDD) vs. Input Voltage 250 150 100 50 19 18 17 16 0 15 0.01 0.1 1 10 100 1000 2.5 3.0 3.5 Output Current (mA) 4.0 4.5 5.0 Input Voltage (V) Supply Current I(VIN) vs. Input Voltage Supply Current I(VIN) vs. Input Voltage 180 90 VOUT = 5V @ no load VOUT = 3.3V @ no load 80 150 Supply Current ( µA) Supply Current ( µ A) 1 10 Output Current (mA) Output Current (mA) 120 90 60 70 60 50 40 30 30 0 1.5 2.0 2.5 3.0 3.5 Input Voltage (V) DS9266-06 June 2004 4.0 4.5 1.5 2 2.5 3 3.5 Input Voltage (V) www.richtek.com 7 RT9266 Switching Swichting Frequency vs. VDD Pin Voltage Start Up Voltage vs. Output Current 1.6 VOUT = 3.3V VIN = 2.4V to 2.8V 1.4 VIN = 3V to 5.6V 500 Start Up Voltage (V) Switching Rate Frequency (KHz). Switching Frequency (kHz) 600 400 300 VIN = 1.2V to 2.2V 1.2 1.0 0.8 0.6 0.4 200 0.2 (In C.R. mode) 0.0 100 0 1 2 3 4 5 0 6 30 60 90 120 150 180 VDD Pin Voltage (V) Output Current (mA) LX Pin Wave Form & Output Ripple LX Pin Wave Form & Output Ripple VIN = 1V, VOUT = 3.3V @ 10mA Output Ripple Output Ripple LX Wave Form LX Wave Form VIN = 1V, VOUT = 3.3V @ 100mA 210 Time (1µs/Div) Time (1µs/Div) LX Pin Wave Form & Output Ripple LX Pin Wave Form & Output Ripple LX Wave Form Time (1µs/Div) www.richtek.com 8 VIN = 2V, VOUT = 3.3V @ 10mA Output Ripple Output Ripple LX Wave Form VIN = 2V, VOUT = 3.3V @ 200mA Time (1µs/Div) DS9266-06 June 2004 RT9266 LX Pin Wave Form & Output Ripple LX Wave Form VIN = 3V, VOUT = 3.3V @ 10mA Output Ripple Output Ripple LX Wave Form VIN = 3V, VOUT = 3.3V @ 200mA LX Pin Wave Form & Output Ripple Time (1µs/Div) Time (1µs/Div) LX Pin Wave Form & Output Ripple LX Pin Wave Form & Output Ripple LX Wave Form VIN = 2V, VOUT = 5V @ 20mA Output Ripple Output Ripple LX Wave Form VIN = 2V, VOUT = 5V @ 200mA Time (1µs/Div) Time (1µs/Div) LX Pin Wave Form & Output Ripple LX Pin Wave Form & Output Ripple LX Wave Form Time (1µs/Div) DS9266-06 June 2004 VIN = 3V, VOUT = 5V @ 20mA Output Ripple Output Ripple LX Wave Form VIN = 3V, VOUT = 5V @ 200mA Time (1µs/Div) www.richtek.com 9 RT9266 LX Pin Wave Form & Output Ripple LX Pin Wave Form & Output Ripple LX Wave Form Time (1µs/Div) Time (1µs/Div) Transient Response Transient Response VIN = 3V, VOUT = 3.3V IOUT = 10mA IOUT = 10mA 200mA Output Transient Voltage VIN = 2V, VOUT = 3.3V Output Transient Voltage 200mA Time (50µs/Div) Time (50µs/Div) Transient Response Transient Response VIN = 3V, VOUT = 5V VIN = 4.5V, VOUT = 5V IOUT = 10mA IOUT = 10mA 200mA Time (50µs/Div) www.richtek.com 10 Output Transient Voltage Output Transient Voltage VIN = 4.5V, VOUT = 5V @ 20mA Output Ripple Output Ripple LX Wave Form VIN = 4.5V, VOUT = 5V @ 200mA 200mA Time (50µs/Div) DS9266-06 June 2004 RT9266 Output Voltage vs. Temperature Output Voltage vs. Temperature 5 3.34 VIN = 3V, VOUT = 5V, IOUT = 100mA VIN = 1.8V, VOUT = 3.3V, IOUT = 100mA 4.98 Output Voltage(V) Output Voltage(V) 3.32 3.3 3.28 3.26 3.24 3.22 4.96 4.94 4.92 4.9 4.88 4.86 4.84 3.2 -40 -10 20 50 80 Temperature (°C) DS9266-06 June 2004 110 140 -40 -10 20 50 80 110 140 Temperature (°C) www.richtek.com 11 RT9266 Application Information Output Voltage Setting Layout Guide Referring to Typical Application Circuits, the output l A full GND plane without gap break. l VDD to GND noise bypass − Short and wide connection voltage of the switching regulator (VOUT) can be set with Eq.1. for the 1µF MLCC capacitor between Pin5 and Pin3. VOUT = ( 1+ R1 R2 ) × 1.25V Eq.1 l VIN to GND noise bypass − Add a capacitor close to L1 inductor, when VIN is not an idea voltage source. l Feedback Loop Design Referring to Typical Application Circuits. The selection of R1 and R2 based on the trade-off between quiescent current consumption and interference immunity is stated below: Minimized FB node copper area and keep far away from noise sources. l Minimized parasitic capacitance connecting to LX and EXT nodes, which may cause additional switching loss. Board Layout Example (2-Layer Board) l Follow Eq.1 l Higher R reduces the quiescent current (Path current (Refer to Typical Application Circuits Figure 2 for the board) = 1.25V/R2), however resistors beyond 5MΩ are not recommended. l Lower R gives better noise immunity, and is less sensitive to interference, layout parasitics, FB node leakage, and improper probing toVFB pins. OUT Prober Parasitics R1 FB Pin _ Q + l R2 A proper value of feed forward capacitor parallel with - Top Layer - 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. 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 DS9266-06 June 2004 RT9266 Outline Dimension 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 0.000 0.152 0.000 0.006 B 1.397 1.803 0.055 0.071 b 0.250 0.559 0.010 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- 26 Surface Mount Package DS9266-06 June 2004 www.richtek.com 13 RT9266 D D1 b1 A C B C1 e e H A b Symbol b1 b Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 1.400 1.600 0.055 0.063 b 0.360 0.520 0.014 0.020 B 2.400 2.600 0.094 0.102 b1 0.406 0.533 0.016 0.021 C -- 4.250 -- 0.167 C1 0.800 -- 0.031 -- D 4.400 4.600 0.173 0.181 D1 -- 1.700 -- 0.067 e 1.400 1.600 0.055 0.063 H 0.380 0.430 0.014 0.017 5-Lead SOT-89 Surface Mount Package www.richtek.com 14 DS9266-06 June 2004