Data Sheet WHITE LED STEP-UP CONVERTER AP3019A General Description Features The AP3019A is an inductor-based DC/DC converter designed to drive up to eight white LEDs in series for backlight. Only one feedback resistor is needed to control the LED current and obtain required brightness. • • • • • • • A constant frequency 1.2MHz PWM control scheme is employed in this IC, which means tiny external components can be used. Specifically, 1mm tall inductor and 0.22µF output capacitor for a typical application is sufficient. Additionally, the Schottky diode in boost circuit is integrated on this chip. AP3019A also provides a disable pin to ease its use for different systems. Inherently Uniform LED Current High Efficiency up to 84% No Need for External Schottky Diode Output Over-voltage Protection (OVP) Fixed 1.2MHz Switching Frequency Uses Tiny 1mm Tall Inductor Requires Only 0.22µF Output Capacitor Applications • • • • • The output over-voltage protection is implemented in AP3019A. When any LED is broken or in other abnormal conditions, the output voltage will be clamped. Cellular Phones Digital Cameras LCD modules GPS Receivers PDAs, Handheld Computers The AP3019A is available in standard SOT-23-6 and TSOT-23-6 packages. SOT-23-6 TSOT-23-6 Figure 1. Package Types of AP3019A Mar. 2010 Rev. 1.7 BCD Semiconductor Manufacturing Limited 1 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Pin Configuration K/KT Package (SOT-23-6/TSOT-23-6) Pin 1 Dot by Marking SW 1 6 VIN GND 2 5 VOUT FB 3 4 CTRL Figure 2. Pin Configuration of AP3019A (Top View) Pin Description Pin Number Pin Name 1 SW 2 GND 3 FB 4 CTRL Shutdown and dimming pin. Connect to 1.8V or higher to enable device; Connect to 0.5V or less to disable device; Connect to a PWM signal to achieve LEDs brightness dimming 5 VOUT Output pin. Connect to the cathode of internal Schottky diode 6 VIN Mar. 2010 Function Switch pin. Connect external inductor Ground Voltage feedback pin. Reference voltage is 200mV Input supply pin. Must be connected to a local bypass capacitor Rev. 1.7 BCD Semiconductor Manufacturing Limited 2 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Functional Block Diagram Figure 3. Functional Block Diagram of AP3019A Ordering Information AP3019A - Circuit Type G1: Green Package K: SOT-23-6 KT: TSOT-23-6 TR: Tape & Reel Package Temperature Range SOT-23-6 -40 to 85°C AP3019AKTR-G1 GAS Tape & Reel TSOT-23-6 -40 to 85°C AP3019AKTTR-G1 L8E Tape & Reel Part Number Marking ID Packing Type BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant and green. Mar. 2010 Rev. 1.7 BCD Semiconductor Manufacturing Limited 3 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit Input Voltage VIN 20 V SW Pin Voltage VSW 38 V Feedback Voltage VFB 20 V VCTRL 20 V θJA 265 °C/W TJ 150 °C Storage Temperature Range TSTG -65 to 150 °C Lead Temperature (Soldering, 10sec) TLEAD 260 °C ESD (Machine Model) 250 V ESD (Human Body Model) 2000 V CTRL Pin Voltage Thermal Resistance (Junction Ambient, No Heat Sink) Operating Junction Temperature to Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability. Recommended Operating Conditions Parameter Symbol Min Max Unit Operating Temperature Range TOP -40 85 °C Input Voltage VIN 2.5 16 V 16 V CTRL Pin Voltage Mar. 2010 VCTRL Rev. 1.7 BCD Semiconductor Manufacturing Limited 4 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Electrical Characteristics VIN =3V, VCTRL=3V, TA =25°C, unless otherwise specified. Parameter Symbol Minimum Operating Voltage VIN (min) Maximum Operating Voltage VIN (max) Conditions Min Typ Max Unit 2.5 V Feedback Voltage (Note 2) VFB FB Pin Bias Current IFB Quiescent Current IQ Shutdown Quiescent Current ISHDN 16 IOUT=20mA, 4 LEDs, TA=-40oC to 85oC 188 200 212 mV 35 100 nA VFB=VIN, no switching 1.5 2.5 3.2 mA VCTRL=0V 2.0 4.0 6.0 µA 1.5 MHz Switching Frequency f 0.9 1.2 Maximum Duty Cycle DMAX 90 93 Switch Current Limit (Note 3) ILIMIT Switch VCE Saturation Voltage VCESAT Switch Leakage Current D=40% 550 D=80% 550 ISW=250mA 360 VSW=5V 0.01 mA High CTRL Pin Voltage % mV 5 µA 1.8 VCTRL V low 0.5 CTRL Pin Bias Current ICTRL 100 µA OVP Voltage VOV 30 V ID=150mA 0.7 V VR(reverse voltage)=23V 0.1 Schottky Forward Drop VDROP Schottky Leakage Current µA VR(reverse voltage)=27V Soft Start Time Thermal Resistance (Junction to Case) 4 150 t 300 SOT-23-6 60 TSOT-23-6 60 µS °C/W θJC Note 2: The bold type specifications of full temperature range are guaranteed by design (GBD). Note 3: The switch current limit is related to duty cycle. Please refer to Figure 15 for detail. Mar. 2010 Rev. 1.7 BCD Semiconductor Manufacturing Limited 5 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Typical Performance Characteristics WLED forward voltage (VF) is 3.45V at IF=20mA, unless otherwise noted. 83 86 82 84 81 82 Efficiency (%) Efficiency (%) 80 79 78 77 80 78 76 76 VIN=3.6V, IOUT=20mA, 8 LEDs 74 CIN=1µF, COUT=0.22µF, L=22µH 73 -50 -25 0 25 50 O IOUT=20mA, 8 LEDs,TA=25 C 74 75 75 CIN=1µF, COUT=0.22µF, L=22µH 72 70 3.0 100 3.5 o Junction Temperature ( C) Figure 4. Efficiency vs. Junction Temperature 5.0 350 85 Schottky Forward Current (mA) 300 84 83 Efficiency (%) 4.5 Figure 5. Efficiency vs. Input Voltage 86 82 81 80 79 O VIN=3.6V, IOUT=20mA,TA=25 C 78 CIN=1µF, COUT=0.22µF, L=22µH 77 76 4.0 Input Voltage (V) 2 3 4 5 6 7 200 150 100 50 0 8 LED's Number 0 200 400 600 800 1000 Schottky Forward Drop (mV) Figure 6. Efficiency vs. LED’s Number Mar. 2010 250 Figure 7. Schottky Forward Current vs. Schottky Forward Drop Rev. 1.7 BCD Semiconductor Manufacturing Limited 6 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Typical Performance Characteristics (Continued) WLED forward voltage (VF) is 3.45V at IF=20mA, unless otherwise noted. 3.5 3.0 25 Quiescent Current (mA) Shutdown Quiescent Current (µA) 30 20 15 10 2.0 1.5 O 1.0 TA=-50 C 0.5 TA=100 C O TA=25 C O TA=25 C 5 0 2.5 0.0 2 4 6 8 10 12 14 16 O 0 2 4 6 8 10 12 14 16 Input Voltage (V) Input Voltage (V) Figure 8. Shutdown Quiescent Current vs. Input Voltage Figure 9. Quiescent Current vs. Input Voltage 1.40 6.0 1.35 5.5 1.30 1.25 Frequency (MHz) Input Current (mA) 5.0 4.5 4.0 3.5 3.0 1.20 1.15 1.10 1.05 1.00 2.5 0.95 2.0 2.5 3.0 3.5 4.0 4.5 0.90 -50 5.0 Input Voltage (V) 0 25 50 75 100 o Junction Temperature ( C) Figure 10. Input Current in Output Open Circuit vs. Input Voltage Mar. 2010 -25 Figure 11. Frequency vs. Junction Temperature Rev. 1.7 BCD Semiconductor Manufacturing Limited 7 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Typical Performance Characteristics (Continued) 210 0.80 208 0.78 206 0.76 Schottky Forward Drop (V) Feedback Voltage (mV) WLED forward voltage (VF) is 3.45V at IF=20mA, unless otherwise noted. 204 202 200 198 196 0.74 0.72 0.70 0.68 0.66 194 0.64 192 0.62 190 -50 -25 0 25 50 75 0.60 -50 100 ID=150mA -25 o Junction Temperature ( C) 25 50 75 100 o Junction Temperature ( C) Figure 12. Feedback Voltage vs. Junction Temperature Figure 13. Schottky Forward Drop vs. Junction Temperature 700 0.50 0.45 VR=10V 0.40 VR=16V 0.35 VR=23V 600 Current Limit (mA) Schottky Leakage Current (µA) 0 0.30 0.25 0.20 0.15 500 400 300 O 0.10 -50 C O 25 C O 100 C 200 0.05 0.00 -50 -25 0 25 50 75 100 30 100 o 40 50 60 70 80 Junction Temperature ( C) Duty Cycle (%) Figure 14. Schottky Leakage Current vs. Junction Temperature Figure 15. Current Limit vs. Duty Cycle Mar. 2010 Rev. 1.7 90 BCD Semiconductor Manufacturing Limited 8 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Typical Performance Characteristics (Continued) WLED forward voltage is 3.45V at IF=20mA, unless otherwise noted. 1.8 450 1.7 Falling Edge Rising Edge 1.6 350 CTRL Pin Voltage (V) Saturation Voltage (mV) 400 300 250 200 150 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 100 0.6 50 50 100 150 200 250 0.5 -50 300 Switch Current (mA) 0 25 50 75 100 O Junction Temperature ( C) Figure 16. Saturation Voltage vs. Switch Current Mar. 2010 -25 Figure 17. CTRL Pin Voltage vs. Junction Temperature Rev. 1.7 BCD Semiconductor Manufacturing Limited 9 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Application Information Operation Over Voltage Protection The AP3019A is a boost DC-DC converter which uses a constant frequency, current mode control scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Figure 3. The AP3019A has an internal open-circuit protection circuit. When the LEDs are disconnected from circuit or fail open, the output voltage is clamped. The AP3019A will switch at a low frequency, and minimize input current. At the start of each oscillator cycle, the SR latch is set and switch Q1 turns on. The switch current will increase linearly. The voltage on sense resistor is proportional to the switch current. The output of the current sense amplifier is added to a stabilizing ramp and the result is fed into the non-inversion input of the PWM comparator A2. When this voltage exceeds the output voltage level of the error amplifier A1, the SR latch is reset and the switch is turned off. Soft Start The AP3019A has an internal soft start circuit to limit the inrush current during startup. The time of startup is controlled by internal soft start capacitor. Please refer to Figure 19. IIN 100mA/div VOUT 5V/div It is clear that the voltage level at inversion input of A2 sets the peak current level to keep the output in regulation. This voltage level is the output signal of error amplifier A1, and is the amplified signal of the voltage difference between feedback voltage and reference voltage of 200mV. So, a constant output current can be provided by this operation mode. VFB 100mV/div VCTRL 2V/div Time 100µs/div Figure 19. Soft Start Waveform VIN=3.6V, 5 LEDs, ILED=20mA Dimming Control Two typical types of dimming control circuit are present as below. First, controlling CTRL Pin voltage to change operation state is a good choice. Second, changing the feedback voltage to get appropriate duty and luminous intensity is also useful. Figure 18. Typical Application Circuit to Decide R1 (1) Adding a Control Signal to CTRL Pin Adding a PWM Signal to CTRL pin directly. The AP3019A is turned on or off by the PWM signal when it is applied on the CTRL pin. The typical frequency of this PWM signal can be up to 2kHz. Please refer to Figure 20. LED Current Control Refer to Figure 18, the LED current is controlled by the feedback resistor R1. LEDs' current accuracy is determined by the regulator's feedback threshold accuracy and is independent of the LED's forward voltage variation. So the precise resistors are preferred. The resistance of R1 is in inverse proportion to the LED current since the feedback reference is fixed at 200mV. The relation for R1 and LED current can be expressed as below: AP3019A CTRL up to 2kHz 200mV R1 = I LED Mar. 2010 Figure 20. Dimming Control Using a PWM Signal in CTRL Pin Rev. 1.7 BCD Semiconductor Manufacturing Limited 10 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Application Information (Continued) (2) Changing the Effective Feedback Voltage There are three methods to change the effective feedback voltage. Third, using a logic signal to change the feedback voltage. For example, the FB pin is connected to the GND through a MOSFET and a resistor. And this MOSFET is controlled a logic signal. The luminous intensity of LEDs will be changed when the MOSFET turns on or off. First, adding a constant DC voltage through a resistor divider to FB pin can control the dimming. Changing the DC voltage or resistor between the FB Pin and the DC voltage can get appropriate luminous intensity. Comparing with all kinds of PWM signal control, this method features a stable output voltage and LEDs current. Please refer Figure 21. Figure 23. Dimming Control Using Logic Signal Figure 21. Dimming Control Using DC Voltage Second, using a filtered PWM signal can do it. The filtered PWM signal can be considered as a varying and adjustable DC voltage. Figure 22. Dimming Control Using a Filtered PWM Voltage Mar. 2010 Rev. 1.7 BCD Semiconductor Manufacturing Limited 11 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Typical Application C: X5R or X7R dielectric L: SUMIDA CDRH5D28R-220NC or equivalent This circuit can work in full temperature Figure 24. Typical Application of AP3019A Mar. 2010 Rev. 1.7 BCD Semiconductor Manufacturing Limited 12 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Mechanical Dimensions SOT-23-6 Unit: mm(inch) 0° 2.820(0.111) 8° 3.020(0.119) 0.300(0.012) 0.400(0.016) 6 0.200(0.008) 5 0.300(0.012) 0.600(0.024) 4 Pin 1 Dot by Marking 1 2 3 0.700(0.028)REF 0.950(0.037)TYP 0.000(0.000) 0.100(0.004) 1.800(0.071) 2.000(0.079) 0.100(0.004) 0.200(0.008) 0.900(0.035) 1.450(0.057) MAX 1.300(0.051) Mar. 2010 Rev. 1.7 BCD Semiconductor Manufacturing Limited 13 Data Sheet WHITE LED STEP-UP CONVERTER AP3019A Mechanical Dimensions (Continued) TSOT-23-6 2.800(0.110) 3.000(0.118) 1.500(0.059) 1.700(0.067) Unit: mm(inch) R0.100(0.004) MIN 0° 8° 2.600(0.102) 3.000(0.118) Pin 1 Dot by Marking 0.370(0.015) MIN 0.950(0.037) BSC 0.100(0.004) 0.250(0.010) 1.900(0.075) BSC 0.250(0.010) BSC GAUGE PLANE 0.700(0.028) 0.900(0.035) 1.000(0.039) MAX 0.000(0.000) 0.100(0.004) Mar. 2010 0.350(0.014) 0.510(0.020) Rev. 1.7 BCD Semiconductor Manufacturing Limited 14 BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE IMPORTANT NOTICE BCD Semiconductor BCD Semiconductor Manufacturing Manufacturing Limited Limited reserves reserves the the right right to to make make changes changes without without further further notice notice to to any any products products or or specifispecifications herein. cations herein. BCD BCD Semiconductor Semiconductor Manufacturing Manufacturing Limited Limited does does not not assume assume any any responsibility responsibility for for use use of of any any its its products products for for any any particular purpose, particular purpose, nor nor does does BCD BCD Semiconductor Semiconductor Manufacturing Manufacturing Limited Limited assume assume any any liability liability arising arising out out of of the the application application or or use use of any of any its its products products or or circuits. circuits. BCD BCD Semiconductor Semiconductor Manufacturing Manufacturing Limited Limited does does not not convey convey any any license license under under its its patent patent rights rights or or other rights other rights nor nor the the rights rights of of others. others. MAIN SITE SITE MAIN - Headquarters BCD Semiconductor Manufacturing Limited BCD Semiconductor Manufacturing Limited - Wafer Fab No. 1600, Zi Xing Road, Shanghai ZiZhu Science-basedLimited Industrial Park, 200241, China Shanghai SIM-BCD Semiconductor Manufacturing Tel: Fax: +86-21-24162277 800,+86-21-24162266, Yi Shan Road, Shanghai 200233, China Tel: +86-21-6485 1491, Fax: +86-21-5450 0008 REGIONAL SALES OFFICE Shenzhen OfficeSALES OFFICE REGIONAL - Wafer FabSemiconductor Manufacturing Limited BCD Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd. - IC Design Group 800 Yi Shan Road, Shanghai 200233, China Corporation Advanced Analog Circuits (Shanghai) Tel: +86-21-6485 1491,YiFax: 0008200233, China 8F, Zone B, 900, Shan+86-21-5450 Road, Shanghai Tel: +86-21-6495 9539, Fax: +86-21-6485 9673 Taiwan Office Shanghai Semiconductor Manufacturing Co., Ltd., Shenzhen Office BCD Taiwan Semiconductor Shenzhen SIM-BCD Office Office (Taiwan) Company Limited Unit A Room 1203, Skyworth Bldg., Gaoxin Ave.1.S., Nanshan Shenzhen, 4F, 298-1, Guang Road,(Taiwan) Nei-Hu District, Taipei, Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd.District, Shenzhen Office BCDRui Semiconductor Company Limited China Taiwan Advanced Analog Circuits (Shanghai) Corporation Shenzhen Office 4F, 298-1, Rui Guang Road, Nei-Hu District, Taipei, Tel: +86-755-8826 Tel: +886-2-2656 2808 Room E, 5F, Noble 7951 Center, No.1006, 3rd Fuzhong Road, Futian District, Shenzhen 518026, China Taiwan Fax: +86-755-88267951 7865 Fax: +886-2-2656 28062808 Tel: +86-755-8826 Tel: +886-2-2656 Fax: +86-755-8826 7865 Fax: +886-2-2656 2806 USA Office BCD Office Semiconductor Corp. USA 30920Semiconductor Huntwood Ave.Corporation Hayward, BCD CA 94544, USA Ave. Hayward, 30920 Huntwood Tel :94544, +1-510-324-2988 CA U.S.A Fax:: +1-510-324-2988 +1-510-324-2788 Tel Fax: +1-510-324-2788