RT9269 Preliminary Tiny Package, High Efficiency, Constant Current LED Driver General Description The RT9269 is a compact, high efficient LED driver with high flexibility of application configurations in charge pump mode or in boost rectifier mode, delivering Tens of mA constant output current for driving 1~4 white LED’s. The 0.25V low reference voltage minimized the power loss across the current-setting resistor. The wide applicable VDD range makes RT9269 suitable for 1 to 4 battery cell applications as well as being supplied with 2.5/3.3/5/6V system powers. The 500kHz 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 current is set with 1 external resistor. And the chip enable (CE) pin can be used for tuning the LED brightness by controlling the ON/OFF duty with external clock. RT9269 is provided in SOT-26 package. Ordering Information RT9269 Features 0.25V Low Reference Voltage 17µA Quiescent (Switch-off) Supply Current Zero Shutdown Mode Supply Current 85% Efficiency 500kHz Fixed Switching Rate Tuning LED brightness with CE pin ON/OFF Duty Small SOT-26 Package Applications LED Module Hand Held Panel Compact Back Light Module Small Battery Charger Constant Current Source Pin Configurations Part Number RT9269CE (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 Package Type E : SOT-26 Operating Temperature Range C: Commercial Standard Marking Information For marking information, contact our sales representative directly or through a RichTek distributor located in your area, otherwise visit our website for detail. DS9269-01 March 2003 www.richtek.com 1 RT9269 Preliminary Typical Application Circuit VIN C1 1µ F C2 1µ F VDD EXT RT9269 To VDD or C3 1µ F CE FB 0.25V GND R1 15Ω Duty Control Brightness R2 15Ω Fig. 1 RT9269 drives single or parallel LED’s in charge pump configuration D1 D2 VIN C1 1µ F VDD C2 1µ F EXT RT9269 To VDD or CE C3 1µ F FB 0.25V GND R1 15Ω Duty Control Brightness Fig. 2 RT9269 drives 2 series connected LED’s in charge pump configuration VIN C1 10µ F R1 1K Q1 C2 1µ F VDD To VDD or L1 10µ H ~ 100µ H LX RT9269 CE C3 10µ F FB GND Duty Control Brightness 0.25V R2 15Ω Fig. 3 RT9269 drives 2~4 series connected LED’s in boost rectifier configuration Note: NICHIA NSCW100 is used for RT9269 LED parts. www.richtek.com 2 DS9269-01 March 2003 RT9269 Preliminary Pin Description Pin No. Pin Name Pin Function 1 CE Chip enable RT9269 gets into shutdown mode when CE pin set to low. 2 EXT Output pin for configuring charge pump or driving external NMOS 3 GND Ground 4 LX Pin for switching 5 VDD Input positive power pin of RT9269 6 FB Feedback input pin Internal reference voltage for the error amplifier is 0.25V. Function Block Diagram RT9269 VDD EXT LX _ FB + VDD 0.25 V Loop Control Circuit R1 R2 CE DS9269-01 March 2003 Q3 NMOS Q1 NMOS Shut Down Over Temp. Detector GND www.richtek.com 3 RT9269 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 -- 0.98 1.05 V Operating VDD Range VDD VDD pin voltage 2 -- 6.5 V No Load Current I (VIN) INO LOAD VIN = 3.3V, VOUT = 5V -- 30 -- µA Switch-off Current I (VDD) ISWITCH OFF VIN = 6V -- 17 -- µA Shutdown Current I (VIN) IOFF CE Pin = 0V, VIN = 6V -- 0.1 1 µA Feedback Reference Voltage VREF Close Loop, VDD = 5V Switching Rate FS VDD = 5V -- 500 -- kHz Maximum Duty DMAX VDD = 5V -- 75 -- % VDD = 5V -- 0.4 -- Ω VDD = 5V -- 500 -- mA EXT ON Resistance to VDD VDD = 5V -- 5 -- Ω EXT ON Resistance to GND VDD = 5V -- 5 -- Ω CE Pin Trip Level VDD = 5V 0.4 0.8 1.2 V LX ON Resistance Current Limit Setting ILIMIT 0.25 V Temperature Stability for VREF Ts -- 50 -- ppm/°C Thermal Shutdown TSD -- 165 -- °C Thermal Shutdown Hysterises ∆TSD -- 10 -- °C www.richtek.com 4 DS9269-01 March 2003 RT9269 Preliminary Typical Operating Characteristics Efficiency vs. Input Voltage Efficiency vs. Vin 85 89 4 LEDs, L = 47 µH 6 LEDs, L = 33 µH 84 83 Efficiency(%) Efficiency (%) 87 85 IOUT = 20 mA 83 IOUT = 15 mA IOUT = 20mA 82 81 81 IOUT = 15mA 80 79 79 2.5 3 3.5 4 4.5 5 5.5 6 3 3.5 4 Input Voltage (V) Frequency vs. VDD 600 5 5.5 6 Efficiency vs. Input Voltage 100 500 IOUT = 20mA @ VIN > 3.8V 90 400 Efficiency (%) Frequency(KHz) 4.5 VIN(V) 300 200 80 IOUT = 15mA @ VIN > 3.6V 70 60 100 FB = GND, TA = 25°C 0 0 1 2 3 VDD (V) 4 5 Refer to Application Circuit Fig. 2 50 3.0 6 3.5 4.0 4.5 5.0 5.5 6.0 Input Voltage (V) VFB vs. Ambient Temperature 256 Efficiency vs. Output Current 100 90 254 80 Efficiency (%) VFB (mV) 252 250 248 VIN = 4.2V 70 VIN = 2.7V 60 VIN = 3.6V 50 40 246 30 244 20 -40 -20 0 20 40 Ambient Temperature (°C) DS9269-01 March 2003 60 80 0.1 1 10 100 Output Current (mA) www.richtek.com 5 RT9269 Preliminary Power ON Waveform Power ON Waveform VIN = 3.0V for 4LEDs VIN VIN = 2.5V for 4LEDs VIN LX LX 200mA/DIV 200mA/DIV IIN IOUT IIN 20mA/DIV Refer to Application Circuit Fig. 3 IOUT 20mA/DIV Refer to Application Circuit Fig. 3 Time (2.5mS/DIV) Time (2.5mS/DIV) LX vs. Output Ripple Waveform LX vs. Output Ripple Waveform VIN = 2.5V for 4LEDs VIN = 3.0V for 4LEDs LX LX Output Output IOUT 20mA/DIV Refer to Application Circuit Fig. 3 IOUT 20mA/DIV Refer to Application Circuit Fig. 3 Time (500nS/DIV) Time (1µS/DIV) Power Up Waveform Power Up Waveform VIN = 3.0V IOUT = 20mA VIN = 2.5V IOUT = 20mA VIN VIN LX LX CE CE 20mA/DIV IOUT 20mA/DIV Refer to Application Circuit Fig. 3 Refer to Application Circuit Fig. 3 Time (250µS/DIV) Time (100µS/DIV) www.richtek.com 6 IOUT DS9269-01 March 2003 RT9269 Preliminary Power On Waveform Power Up Waveform VCE = 1.25V VIN = 3.8V IOUT = 20mA VCE = VIN = 3.8V IOUT = 20mA VCE VCE IIN IIN IOUT CH1: 2V/DIV Refer to Application Circuit Fig. 2 IOUT Time (10mS/DIV) CH1: 2V/DIV Refer to Application Circuit Fig. 2 Time (500µS/DIV) Shutdown Waveform LX vs. Ripple Waveform VCE = 1.25V VIN = 3.8V IOUT = 20mA VLX VLX IIN IOUT VCE = VIN = 3.8V IOUT = 20mA VOUT IOUT Refer to Application Circuit Fig. 2 CH1: 2V/DIV CH1: 2V/DIV Refer to Application Circuit Fig. 2 Time (500µS/DIV) Time (1µS/DIV) Power On Waveform Power Up Waveform VCE = VIN = 3.2V IOUT = 40mA VCE = 1.2V VIN = 3.2V IOUT = 40mA VIN VIN IIN IIN CH1: 2V/DIV CH2: 200mA/DIV IOUT IOUT CH1: 2V/DIV CH2: 100mA/DIV VLX VLX Refer to Application Circuit Fig. 1 Time (5mS/DIV) DS9269-01 March 2003 Refer to Application Circuit Fig. 1 Time (250µS/DIV) www.richtek.com 7 RT9269 Preliminary Shutdown Waveform VIN VCE = 1.2V VIN = 3.2V IOUT = 40mA LX vs. Output Ripple Waveform VIN IIN IIN IOUT VLX CH1: 2V/DIV VOUT CH2: 200mA/DIV Ripple Refer to Application Circuit Fig. 1 VIN VIN LX LX IOUT VIN = 3.0V IOUT = 20mA Time (1mS/DIV) www.richtek.com 8 Refer to Application Circuit Fig. 1 Brightness Control Brightness Control CE CH1: 1V/DIV Time (1µS/DIV) Time (250µS/DIV) 80% Duty External Signal VCE = VIN = 3.2V IOUT = 40mA CE IOUT 80% Duty External Signal VIN = 2.5V IOUT = 20mA Time (1mS/DIV) DS9269-01 March 2003 RT9269 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 DS9269-01 March 2003 www.richtek.com 9 RT9269 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 10 DS9269-01 March 2003