SC4509 Highly Integrated Step-Up Converter for White LED Applications in MLPD-W8-2x2 POWER POWERMANAGEMENT MANAGEMENT Description Features The SC4509 is a highly integrated step-up DC/DC converter targeted for white LED backlighting applications. It is designed to drive up to five LEDs with a wide input voltage range of 2.7 to 10 volts. Designed for 20V output voltage, the SC4509 operates with a constant 1.2MHz PWM frequency. To optimize efficiency, the feedback voltage is set to only 199mV, minimizing the power loss in the current setting resistor. The product requires only four external components (CIN, COUT, L and RSET), making it ideal for applications that require low cost and minimal PCB area. VIN range: 2.7V — 10V Integrated Schottky diode 81% efficiency Requires only 4 external components Up to 20V of output voltage 30mA maximum LED current Open LED protection (OVP) 1.2MHz PWM switching frequency Low feedback voltage (20OmV typical) Wide range of PWM dimming Drives up to 5 LEDs 500mA switch current limit 220nF output capacitor Available in 2mm x 2mm x 0.75mm MLPD-W8 and SOT23-6 packages Packages are fully WEEE and RoHS compliant The SC4509 offers current limit and over-voltage protection (OVP) to safeguard the device under extreme operating conditions. If the LEDs become disconnected or fail in an open state condition, OVP circuitry will be activated to shut down the device. The EN/SS pin allows the device to be placed in power-down mode, disabling the control circuitry to reduce input current. Applications Digital Video Cameras White LED Backlight Driver OLED Display Driver Portable Media Players GPS Receivers Cellular Phones PDAs and Handheld Computers Typical Application Circuit Vin L1 Vo 22μH LED1 LED2 C2 0.22μF 1 LED4 C1 1μF EN/SS 2 4 GND SC4509 EN/SS March 26, 2007 SW VIN VOUT 5 6 LED3 U2 1 FB 3 R1 www.semtech.com SC4509 PRELIMINARY POWER MANAGEMENT Absolute Maximum Rating Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions for extended periods of time may affect device reliability. Parameter Symbol Maximum Units Input Supply Voltage VIN -0.3 to 20 V SW Voltage VSW -0.3 to 30 V Maximum Output Voltage VOUT 30 V Feedback Voltage VFB -0.3 to 20 V VEN/SS -0.3 to VIN + 0.3 V TJ 125 °C TSTG -65 to +150 °C EN/SS Voltage Maximum Junction Temperature Storage Temperature Range MLPD-W8 Thermal Impedance Junction to Ambient(1) 78 θJA SOT23-6 C/W 165 Lead Temperature (Soldering), 10s (SOT23-6 package only) TLEAD 300 °C Peak IR Flow Temperature, (10-40sec) TPKG 260 °C ESD Rating (Human Body Model)(2) VESD 2 kV Note: 1) Calculated from package in still air, mounted to 3”x 4.5”, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards. 2) Tested in accordance to JEDEC standard JESD22-A114B. Electrical Characteristics Unless specified: VIN = VEN/SS = 3.6V; CIN = 1μF; COUT = 0.22μF; L = 22μH; unless otherwise noted, TA = +25°C for Typ, -40ºC to 85°C for Min and Max. Parameter Symbol Input Voltage VIN Quiescent Current IQ Feedback Voltage VFB Feedback Pin Bias Current IQFB Switching Frequency fOSC Maximum Output Voltage VOUT Switch Saturation Voltage VCESAT ISW = 85mA; TA=25 °C Maximum Duty Cycle DMAX VFB = GND 90 Switch Current Limit Icl ILOAD = 0; TA=25 °C 300 Switch Leakage Current ILKG Shutdown Current ISHD PWM Dimming Frequency(1) fDIM EN/SS Threshold Low VIL EN/SS Threshold High VIH © 2007 Semtech Corp. Conditions Min Typ Max Units 10 V 2.6 3.3 mA 199 216 mV 35 100 nA 1.2 1.4 MHz 2.7 No switching 182 TA=25 °C 1.0 20 V 160 300 mV % 500 700 mA VSW = 5V; VOUT = Open 0.01 5.0 μA VEN/SS = GND; VIN = 3V; VOUT = Open 3 5 μA 1 10 kHz 50 mV 1.8 2 V www.semtech.com SC4509 POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified: VIN = VEN/SS = 3.6V; CIN = 1μF; COUT = 0.22μF; L = 22μH; unless otherwise noted, TA = +25°C for Typ, -40ºC to 85°C for Min and Max. Parameter Symbol Conditions EN/SS Input Low Current IIL VEN/SS = GND EN/SS Input High Current IIH Output Over-Voltage Protection OVP Schottky Forward Drop Vf_sch Schottky Leakage Current If_sch Min Typ 60 25 Max Units 1.0 μA 100 μA 30 V ID = 150mA 0.7 V VOUT = 25V; VSW = GND 1.0 4.0 μA Note: 1. Guaranteed by design. © 2007 Semtech Corp. 3 www.semtech.com SC4509 PRELIMINARY POWER MANAGEMENT Pin Configuration Ordering Information Part Numbers 1 VOUT 6 SC4509SKTRT(1)(2) GND 2 5 VIN FB 3 4 EN/SS SC4509WLTRT(1)(2) 1 GND 2 GND 3 VOUT 4 TOP VIEW T SC4509EVB(3) SOT23-6 MLPD-W8 2mmx2mmx0.75mm Evaluation Board Notes: (1) Only available in tape and reel packaging. A reel contains 3000 devices. (2) Lead-free package. This product is fully WEEE and RoHS compliant. (3) Specify package preference when ordering. 6-pin - SOT23 FB Package SW 8 EN/SS 7 VIN 6 SW 5 VOUT 8-pin - MLPD 2X2 Marking Information TOP MARK BP00 BOTTOM MARK yyww Marking for SOT23, 6 Lead Package: yyww = Datecode (Example: 0652) © 2007 Semtech Corp. 4 www.semtech.com SC4509 POWER MANAGEMENT Pin Descriptions SOT23 MLPD 2X2 Pin Name 1 4, 5 VOUT Cathode side of the Schottky output voltage. Connect a 0.22μF capacitor from this pin to ground. 2 2,3 GND Ground connection 3 1 FB 4 8 EN/SS 5 7 VIN Input voltage pin. Connect a 1μF capacitor from this pin to GND. 6 6 SW Switching pin - collector of the internal switch. N/A T © 2007 Semtech Corp. Function Feedback input pin. Connect a resistor from this pin to GND to program the LED current. Enable pin. When connected to logic high, the converter is enabled. When connected to logic low, the converter is disabled. The LED brightness can be controlled by applying a PWM signal to this pin. Exposed pad (bottom); connect to GND directly beneath package. 5 www.semtech.com SC4509 PRELIMINARY POWER MANAGEMENT Block Diagram SW Internal Schottky VOUT FB VIN VREF PWM 199mV OVP 1.25V R Q S ∑ S GND EN/SS Ramp Generator 1.2MHz Oscillator Theory of Operation Over-Voltage Protection (OVP) To prevent the output voltage from exceeding the maximum switch voltage rating (30V), an over-voltage protection circuit is integrated. As soon as the output voltage exceeds the OVP threshold, the converter stops switching and the output voltage starts to drop. When the output voltage drops back below the OVP threshold, the converter resumes operation. This sequence will repeat for as long as is necessary. The SC4509 is a constant frequency PWM step-up regulator IC designed to operate with an input voltage range from 2.7V to 10V. A maximum output voltage of 20V allows for up to five LEDs to be connected in series, providing even illumination by passing the same output current through each LED. Designed for a low 199mV, the feedback voltage has a direct effect on the converter efficiency. Because the voltage drop across the feedback resistor does not contribute to the output power (LED brightness), the lower the feedback voltage, the higher the efficiency. A 1.2MHz oscillator frequency saves board space by reducing external component sizes, making the SC4509 ideal for battery-operated products. Enable and PWM Dimming The SC4509 provides the EN/SS pin to serve multiple functions. Its main function is as an enable pin (active high). It also can be used to control LED brightness when a PWM signal (up to 10kHz) of varying duty cycle is applied. A third function acts as a soft-start control. Soft start can be implemented by ramping the voltage applied to the pin at startup or by slowly increasing the PMW duty cycle. The SC4509 can be configured as a voltage regulated boost converter or as a current-regulating boost converter for driving white LEDs. The device is designed to be stable without additional external components in both cases. © 2007 Semtech Corp. 6 www.semtech.com SC4509 POWER MANAGEMENT Applications Information Programming the LED Current Please refer to the Typical Application Circuit on page 1. The LED current is programmed by connecting a resistor (R1) between the FB pin and GND. The LED current in mA is given by the following equation: ILED = 199/R1 where R1 value is in Ohms. Setting the Output Voltage The non-inverting input of the internal error amplifier is tied to a 199mV voltage reference. A simple voltage divider (R1 at the top and R2 at the bottom) sets the converter output voltage. Please refer to the Application Circuit for OLED Panels on the next page. The voltage feedback gain h = 0.199/Vo is related to the divider resistors value as h R2 R1 R2 Once either R1 or R2 is chosen, the other can be calculated for the desired output voltage Vo. Since the number of standard resistance values is limited, the calculated resistance may not be available as a standard value resistor. As a result, there will be a set error in the converter output voltage. This non-random error is caused by the feedback voltage divider ratio. It cannot be corrected by the feedback loop. © 2007 Semtech Corp. 7 www.semtech.com SC4509 PRELIMINARY POWER MANAGEMENT Application Circuit for OLED Panels L1 Vo VIN VIN C1 1 EN/SS 2 EN/SS GND SC4509 4 OLED PANEL R1 VOUT 5 SW U2 6 22μH FB C2 1μF 3 R2 1μF © 2007 Semtech Corp. 8 www.semtech.com SC4509 POWER MANAGEMENT Typical Characteristics Efficiency vs. LED Current VIN = 3.3V, VOUT = 16V, (4 LED) Efficiency vs. LED Current VIN = 2.7V, VOUT = 16V, (4 LED) 80% 85% 75% 80% 70% 75% 70% Efficiency (%) Efficiency (%) 65% 60% 55% 50% 45% 65% 60% 55% 50% 45% 40% 40% 35% 35% 30% 30% 0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 ILED (mA) 16 18 20 22 24 26 28 30 32 Efficiency vs. LED Current vs. Input Voltage VOUT = 12V, (3 LED) 85% 85% 80% 80% 75% 75% 70% 70% 65% 65% Efficiency (%) Efficiency (%) 14 ILED (mA) Efficiency vs. LED Current VIN = 3.6V, VOUT = 16V, (4 LED) 60% 55% 50% VIN = 2.7V VIN = 3.6V 60% 55% 50% 45% 45% 40% 40% 35% 35% 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 0 5 10 15 ILED (mA) 203.0 12 20 25 30 35 ILED (mA) Feedback Voltage vs. Temperature vs. LED Current, VOUT = 16V Frequency vs. Temperature vs. Input Voltage, VOUT = 16V 1.20 VIN = 2.7V 202.0 1.15 FBK (mV) Frequency (MHz) ILED = 20mA 201.0 ILED = 30mA 200.0 199.0 VIN = 3.3V 1.10 VIN = 3.6V 1.05 198.0 197.0 1.00 -40 -20 0 20 40 60 80 100 -40 Temperature (Deg. C) © 2007 Semtech Corp. -20 0 20 40 60 80 Temperature (Deg. C) 9 www.semtech.com SC4509 PRELIMINARY POWER MANAGEMENT Typical Characteristics (Cont.) Output Voltage vs. EN/SS Voltage vs. Temperature, VIN = 3.6V; VOUT = 16V EN/SS Input Current vs. EN/SS Voltage vs. Temperature, VIN = 3.6V; VOUT = 16V 55.0 16.0 50.0 45.0 14.0 40°C 40.0 25°C VOUT (V) IEN/SS (μA) 35.0 30.0 40°C 25.0 25°C 12.0 10.0 85°C 8.0 20.0 15.0 6.0 85°C 10.0 4.0 5.0 2.0 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0.0 2.2 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 90 100 VEN/SS (Volts) VEN/SS (Volts) LED Current vs. PWM Dimming Duty Cycle VIN = 3.6V; VOUT = 16V; FPWM = 10kHz LED Current vs. PWM Dimming Duty Cycle VIN = 3.6V; VOUT = 16V; FPWM = 1kHz 22 22 20 20 18 18 16 14 ILED (mA) ILED (mA) 16 14 12 12 10 8 6 10 4 8 2 0 6 15 25 35 45 55 65 75 85 0 95 10 20 30 40 50 70 80 DTY (%) DTY (%) Switch Current Limit vs. Complementary Duty Cycle (1-D) vs. Temperature 800 60 700 -40°C Switch Current Limit vs. Temperature vs. Complementary Duty Cycle (1-D) 650 10% 700 20% 600 550 500 Current Limit (mA) Current Limit (mA) 600 0°C 400 25°C 300 500 450 60% 400 90% 350 40% 85°C 300 200 250 100 200 0 10 20 30 40 50 60 70 80 90 -40 100 © 2007 Semtech Corp. -20 0 20 40 60 80 100 Temperature (Deg. C) (1-D) (%) 10 www.semtech.com SC4509 POWER MANAGEMENT Typical Characteristics (Cont.) Startup Current VIN = 3.6V; ILED = 30mA; VOUT = 16V (4 LEDs) Switch Complementary Duty Cycle vs. Input Voltage vs. LED Current, VOUT = 16V, (4 LED) 35.0% 30.0% 25.0% ILED = 20mA (1-D) (%) 20.0% ILED = 30mA 15.0% 10.0% 5.0% 0.0% 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 VIN (V) Switching Waveform VIN = 3.6V; ILED = 20mA; VOUT = 16V (4 LEDs) © 2007 Semtech Corp. 11 www.semtech.com SC4509 PRELIMINARY POWER MANAGEMENT Layout Example Top Layer Bottom Layer © 2007 Semtech Corp. 12 www.semtech.com SC4509 POWER MANAGEMENT Outline Drawing - SOT23-6 DIM A e1 2X E/2 A A1 A2 b c D E1 E e e1 L L1 N 01 aaa bbb ccc D N E EI 1 2 ccc C 2X N/2 TIPS e B D aaa C A2 SEATING PLANE DIMENSIONS INCHES MILLIMETERS MIN NOM MAX MIN NOM MAX .057 .035 .000 .006 .035 .045 .051 .010 .020 .003 .009 .110 .114 .122 .060 .063 .069 .110 BSC .037 BSC .075 BSC .012 .018 .024 (.024) 6 0° 10° .004 .008 .008 A H A1 C bxN bbb 1.45 0.15 1.15 1.30 0.50 0.22 2.90 3.10 1.60 1.75 2.80 BSC 0.95 BSC 1.90 BSC 0.30 0.45 0.60 (0.60) 6 0° 10° 0.10 0.20 0.20 0.90 0.00 .90 0.25 0.08 2.80 1.50 C A-B D c GAGE PLANE 0.25 L 01 (L1) SEE DETAIL A DETAIL A SIDE VIEW NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H- 3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. Land Pattern - SOT23-6 X DIM (C) G Z Y P DIMENSIONS MILLIMETERS INCHES (.098) .055 .037 .024 .043 .141 C G P X Y Z (2.50) 1.40 0.95 0.60 1.10 3.60 NOTES: 1. © 2007 Semtech Corp. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 13 www.semtech.com SC4509 PRELIMINARY POWER MANAGEMENT Outline Drawing - MLPD-W8 2x2 A B D DIM E PIN 1 INDICATOR (LASER MARK) A SEATING PLANE aaa C A2 A1 C A A1 A2 b D D1 E E1 e L N aaa bbb DIMENSIONS INCHES MILLIMETERS MIN NOM MAX MIN NOM MAX .028 .030 .031 .000 .001 .002 (.008) .007 .010 .012 .075 .079 .083 .059 .063 .067 .075 .079 .083 .031 .035 .039 .020 BSC .008 .012 .016 8 .003 .003 0.70 0.75 0.80 0.00 0.02 0.05 (0.20) 0.18 0.25 0.30 1.90 2.00 2.10 1.50 1.60 1.70 1.90 2.00 2.10 0.80 0.90 1.00 0.50 BSC 0.20 0.30 0.40 8 0.08 0.08 D1 1 2 LxN E/2 E1 N bxN bbb e C A B e/2 D/2 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. Land Pattern - MLPD-W8 2x2 H R DIM G (C) K C G H K P R X Y Z Z Y X DIMENSIONS INCHES MILLIMETERS (.079) .051 .063 .035 .020 .006 .012 .028 .106 (2.00) 1.30 1.60 0.90 0.50 0.15 0.30 0.70 2.70 P NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 3. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. © 2007 Semtech Corp. 14 www.semtech.com SC4509 POWER MANAGEMENT Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com © 2007 Semtech Corp. 15 www.semtech.com