RT9268 Preliminary Tiny Package, 1.3MHz, Step-up DC/DC Converter General Description The RT9268 is a compact, 1.3MHz, step-up DC/DC converter with a current mode PWM control loop, providing a stable and efficient operation without external compensation. The high switching rate makes RT9268 suitable for ADSL applications providing sufficient output current for variant types of line drivers. The 2V~6V wide applicable VIN range makes it suitable for applications. This device is available space-saving SOT-26 package. The output voltage is set with 2 external resistors. Both internal 2A switch and driver for driving external power devices (NMOS or NPN) are provided. Ordering Information Features 1.3MHz Switching Rate Below 2V Low Start-up Input Voltage Sufficient Supply Capability for Supplying XDSL Line Drivers Zero Shutdown Mode Supply Current Providing Flexibility for Using Internal and External Power Switches Small SOT-26 Package Applications XDSL Line Drivers USB Devices PCMCIA Cards Mini-PCI Cards Pin Configurations Part Number RT9268 Package type E : SOT-26 RT9268CE (Plastic SOT-26) Pin Configurations TOP VIEW 6 5 4 1 2 3 Operating temperature range C: Commercial standard DS9268-00 October 2002 1. 2. 3. 4. 5. 6. CE EXT GND LX VDD FB www.richtek.com 1 RT9268 Preliminary Typical Application Circuit L1 VIN 3.0V~ 5.5V R1 1K 3.3 µH C3 1µF C2 10µF SL12 C1 1µF Q1 VDD CE EXT LX RT9268 FB R2 12K C6 0.1µF L2 GND C4 1µF C5 10µF VOUT 18V R3 910 L2 : CL321611T-R22K-S/ YAGEO Fig. 1 RT9268 Application for XDSL 18V Line Drivers L1 VIN 4.5V~ 5.2V R1 1K C2 10µF C3 1µF 3.3 µH C1 1µF SL12 Q1 VDD CE EXT LX RT9268 FB GND C4 1µF C7 1µF C6 0.1µF L2 C5 10µF VOUT1 12V R2 8.6K R3 1K SS12 C8 10µF VOUT2 -12V L2 : CL321611T-R22K-S/ YAGEO Fig. 2 DS9268-00 October 2002 RT9268 Application for USB-XDSL +-12V Line Drivers www.richtek.com 2 RT9268 Preliminary Pin Description Pin No. Pin Name Pin Function 1 CE Chip enable RT9268 gets into shutdown mode when CE pin set to low. 2 EXT Output pin for driving external NMOS 3 GND Ground 4 LX Pin for switching 5 VDD Input positive power pin of RT9268 6 FB Feedback input pin Internal reference voltage for the error amplifier is 1.25V. Function Block Diagram RT9268 VDD EXT LX _ FB + VDD 1.25V Loop Control Circuit R1 R2 CE DS9268-00 October 2002 Q2 NMOS Q1 NMOS Down Shut Dow n Over Temp. Detector GND www.richtek.com 3 RT9268 Preliminary Absolute Maximum Ratings • Supply Voltage LX Pin Switch Voltage Other I/O Pin Voltages LX Pin Switch Current EXT Pin Driver Current Power Dissipation, PD @ TA = 25°C SOT-26 Package Thermal Resistance SOT-26, θJA Operating Junction Temperature Storage Temperature Range -0.3V to 7V -0.3V to (VDD + 0.8V) -0.3V to (VDD + 0.3V) 2.5A 200mA 0. 25W 250°C/W 125°C -65°C ~ +150°C Electrical Characteristics (VIN = 3.3V, VDD set to 5V, Load Current = 0, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Units Start-UP Voltage VST IL = 1mA -- -- 2 V Operating VDD Range VDD VDD pin voltage 2 -- 6 V No Load Current I (VIN) INO LOAD VIN = 3.3V, VOUT = 5V -- 3 -- mA Switch-off Current I (VDD) ISWITCH OFF VIN = 6V -- 1 -- mA Shutdown Current I (VIN) IOFF CE Pin = 0V, VIN = 6V -- 0.1 1 µA Feedback Reference Voltage VREF 1.225 1.25 1.275 V Switching Rate FS VDD = 5V -- 1.3 -- MHz Maximum Duty DMAX VDD = 5V -- 95 -- % VDD = 5V -- 0.3 -- Ω VDD = 5V -- 2 -- A EXT ON Resistance to VDD VDD = 5V -- 5 -- Ω EXT ON Resistance to GND VDD = 5V -- 5 -- Ω LX ON Resistance Current Limit Setting ILIMIT Line Regulation ∆VLINE VIN = 2 ~ 4V, IL = 1mA -- 10 -- mV/V Load Regulation ∆VLOAD VIN = 3.3V, IL = 1 ~ 100mA -- 0.25 -- mV/mA 0.4 0.8 1.2 V CE Pin Trip Level VDD = 5V Temperature Stability for Vout Ts Guaranteed by Design -- 50 -- ppm/°C Thermal Shutdown TSD Guaranteed by Design -- 165 -- °C Thermal Shutdown Hysterises ∆TSD Guaranteed by Design -- 10 -- °C DS9268-00 October 2002 www.richtek.com 4 RT9268 Preliminary Typical Operating Characteristics Output Voltage vs. Output current Efficiency vs.Output Current 100 12.5 VOUT = 12V TA=25°C 12.4 VIN = 5.5V VIN = 5.2V 80 VIN = 5.0V VIN = 4.5V 70 60 VOUT = 12V TA=25°C 12.3 Output voltage (V) . Efficiency (%) 90 12.2 VIN = 5.5V 12.1 12 VIN = 4.5V 11.9 VIN = 5.0V 11.8 VIN = 5.2V 11.7 50 11.6 0 40 0.1 1 10 100 25 50 1000 1K 75 100 125 150 175 200 Output OutputCurrent current(mA) (mA) Output Currrent (mA) Output Voltage vs. Output Current Efficiency vs. Output Current 17.8 90 VOUT = 18V TA=25°C VOUT = 18V TA=25°C 17.78 Output Voltage (V) 17.76 Efficiency (%) 80 70 VIN = 5.5V 60 VIN = 5.5V 17.74 VIN = 5.0 V 17.72 VIN = 5.2V 17.7 VIN = 4.5V 17.68 17.66 VIN = 5.0V 17.64 VIN = 5.2V 17.62 VIN = 4.5V 17.6 0 50 0.1 1 10 100 20 40 60 80 100 120 Output Current (mA) 1000 1K Output Current (mA) Start up Waveform Input Current vs. Input Voltage 0.9 0.8 VIN = 5V, 5V/DIV 0.7 VOUT = 12V, 5V/DIV LX, 5V/DIV Input Current (mA) VIN = 5V, VOUT = 12V,IOUT= 200mA,TA=25℃ 0.6 0.5 0.4 0.3 VOUT = 18V, IOUT= 0mA,TA=25℃ 0.2 0.1 0 4.5 4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5 Input Voltage (V) DS9268-00 October 2002 www.richtek.com 5 RT9268 Preliminary Package Information D 6 4 C B 1 b 3 H A A1 e Symbol L 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 DS9268-00 October 2002 www.richtek.com 6 Preliminary DS9268-00 October 2002 RT9268 www.richtek.com 7 Preliminary RT9268 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] DS9268-00 October 2002 www.richtek.com 8