400mA Synchronous y Step-Down p DC/DC Converters New Product Release XC9244/XC9245 Series Digital Camera Mobile Phone Notebook PC Portable Gaming The XC9244/XC9245 series are small step-down synchronous DC/DC converters with an internal 0.65㱅 P-ch driver transistor and an internal 0.45㱅 N-ch switch transistor. A stable current up to 400mA maximum can be supplied using only a coil and two small ceramic capacitors as external components. The XC9244 uses PWM fixed control and the XC9245 uses PWM/PFM auto switching control to achieve a high-efficiency DC/DC converter with low ripple voltage. The small USPN-6 package is used to enable space-saving. USPN-6 (1.3mm㬍1.3mm㬍0.4mm) Miniaturization achieves space-saving! 1 䂓TYPICAL APPLICATION CIRCUIT 䂓Mounting area comparison XC9235 / XC9236 (600mA) L=4.7㱘H VOUT 400mA VIN VIN Lx CE CIN=4.7㱘F (ceramic) CL 2012 size VSS 50％ Reduction CL CIN 1608 size XC9235 XC9236 USP-6C CL=10㱘F (ceramic) VOUT CE CIN 2012 size XC9244 / XC9245 (400mA) Miniaturized 1608 size USPN-6 Using a small coil and small capacitors, a high-efficiency DC/DC converter can be mounted using only about half the area of previous products. By simply adding a coil to the small LDO mounting area, a space-saving, high-efficiency power supply with low heat generation can be configured. 2 Low-ripple voltage is maintained from light-load currents to heavy-load currents. 䂓VIN=4.2V䇭VOUT=3.3V 䂓 Ripple Voltage vs. Output Current䇭䇭 CIN=4.7㱘F(CM105X5R475) L=4.7㱘H(SPM3012),CL=10㱘F(CM105X5R106) 50 90 Ripple Voltage: Vr (mV) Efficiency : EFFI(%) 100 80 70 60 XC9245 XC9244 50 40 30 20 10 1 10 100 30 20 XC9244 1000 XC9245 10 0 0.1 0 0.1 Regular ICs 40 1 10 100 1000 Output Current : IOUT(mA) Output Current : IOUT(mA) To maintain high efficiency from light loads to heavy loads, the XC9245 automatically switches between PWM control and PFM control based on the load current. Near the switching point, ripple voltage normally grows large due to coil current overlay. The XC9245 uses unique circuit technology to enable smooth switching that holds down current overlay while maintaining high efficiency. This achieves low ripple voltage across the full range of loads. The ripple voltage depends on the ESR (Equivalent Series Resistance) of the capacitor, and the efficiency depends on the DCR (Direct Current Resistance) of the coil. Features 2.3V 䌾 6.0V Input Voltage Output Voltage Selectable 0.8V 䌾 4.0V䋨0.05V Increments䋩 Driver Transistor Built-In 0.65㱅P-ch Driver Transistor Maximum Duty Cycle 100% Function Current Limiter Circuit (Constant Current & Latching) Capacitor Low ESR Ceramic Capacitor Control Methods Output Current 0.45㱅N-ch Synchronous Switch Transistor 94% (VIN=4.2V VOUT=3.3V) 400mA PWM (XC9244) PWM/PFM Auto(XC9245) Oscillation Frequency 1.2MHz ±15% Package USPN-6 High Efficiency CLHigh Speed Discharge, Soft Start Circuit www.torex.co.jp/english/ July 2011 䃂 Values shown in this sheet can be changed without any prior notice. New Product Release 400mA Synchronous Step-Down DC/DC Converters XC9244/XC9245 Series 3 High efficiency is achieved by optimization of the switching transistor size. 䂓Power loss in a step-down synchronous DC/DC 䂓VIN=5.0V䇭VOUT=1.5V VIN 100 (P-ch) Thermal loss due to on-resistance and output current of switching transistor. Coil 㪣㪯 DC/DC Converters Control Circuit CE DC resistance component of coil 䋨 䋩 㪚㪣 Low Side Switch (N-ch) 㪭㪦㪬㪫 90 80 Efficiency : EFFI(%) High Side Switch XC9236 60 50 XC9245 40 LDO 30 20 10 Thermal loss due to DC resistance and output current of coil. VSS 70 0 0.1 1 10 100 1000 Output Current : IOUT(mA) 䂓Coil current waveform (continuous) when the dropout voltage is large Power loss in a synchronous step-down DC/DC converter is partly due to loss in the switching transistors. As an innovation to miniaturize the XC9244/XC9245 series without losing efficiency, we optimized the size of the synchronous rectification switching transistor. Step-down DC/DC converters are often used when the dropout voltage is large. Focusing on the fact that the on-time of the low-side switch becomes longer when the dropout voltage is large, we set the low-side (N-ch) on-resistance to 0.45㱅, smaller than the 0.65㱅 high-side (P-ch) on-resistance. Also, we succeeded to reduce parasitic capacitances of the switching transistors with the miniaturization. As shown in the above graph, the result is a high-efficiency greater than our standard-size XC9236 series, particularly when the dropout voltage is large and output current is small. Low Side Switch ON Time High Side Switch ON Time 4 Comparison of step-down synchronous DC/DC converter characteristics. ޣThe optimum product can be selected for the currentޤ 䇭䇭䇭XC9244/XC9245 䇭䇭䇭䇭䇭䇭䇭䇭䇭XC9235/XC9236/XC9237 Maximum Output Current Output Voltage Input Voltage Oscillation Frequency Control High Side P-ch ON Resistance Low Side N-ch ON Resistance Supply Current 400mA 0.8V䌾4.0V (0.05V Increments) 䇭䇭䇭䇭XC9223/XC9224 䇭䇭䇭䇭䇭 1000mA 2000mA 0.8V䌾4.0V (0.05V Increments) 0.9V䌾VIN can be set with using externally connected resistors 0.9V䌾VIN can be set with using externally connected resistors 2.3V䌾6.0V 1.8V䌾6.0V 2.5V䌾6.0V 1.2MHz±15% 1.2MHz±15% 3MHz±15% 1MHz±15% 䋨Synchronous external clock䋩 2MHz±15% 䋨Synchronous external clock䋩 PWM䋺䋨XC9244䋩 PWM/PFM Auto䋺䋨XC9245䋩 XC9242/XC9243 600mA PWM䋺䋨XC9235䋩 PWM/PFM Auto䋺䋨XC9236䋩 Manual䋺(XC9237) PWM/PFM Auto (With PWM Fixed Pin)䋺 䋨Both XC9223/XC9224䋩 2.7V䌾5.5V 1.2MHz±15% PWM䋺䋨XC9242䋩 PWM/PFM Auto䋺(XC9243) 0.65Ω @ VIN=5.0V 0.35Ω @ VIN=5.0V 0.19Ω @ VIN=5.0V 0.11Ω @ VIN=5.0V 0.45Ω @ VIN=5.0V 0.45Ω @ VIN=5.0V 0.21Ω @ VIN=5.0V 0.11Ω @ VIN=5.0V 18㱘A 15㱘A(1.2MHz) 30㱘A(1MHz) 41㱘A Package (mm) USPN-6 (1.3×1.3×0.4) SOT-25 (2.9×2.8) USP-6C (1.8×2.0×0.6) USP-6EL (1.8×2.0×0.4) MSOP-10 (3.0×4.9) USP-10B (2.9×2.6×0.6) USP-10B (2.9×2.6×0.6) Function 䊶CE Function 䊶Current Limiter Circuit 䋨Constant Current & Latching䋩 䊶CL High Speed Discharge 䊶High Speed Soft Start 䊶CE Function 䊶Current Limiter Circuit 䋨Constant Current & Latching䋩 䊶CL High Speed Discharge 䊶High Speed Soft Start 䊶Synchronous External Clock 䊶CE Function 䊶Current limit binary switching selection 䋨Constant Current & Latching䋩 䊶Short-circuit Protection 䊶Thermal Shutdown 䊶Soft Start 䊶Voltage Detect Function 䊶CE Function 䊶Current Limiter Circuit 䋨Constant Current & Automatic Recovery䋩 䊶Thermal Shutdown 䊶CL High Speed Discharge 䊶Soft Start (XC9224 is always on) www.torex.co.jp/english/ July 2011 䃂 Values shown in this sheet can be changed without any prior notice.