Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 General Description Features The AP3019 is an inductor-based DC/DC converter designed to drive up to five white LEDs in series for backlight. Only one feedback resistor is needed to control the LED current and obtain satisfied brightness. · · · · · · · · A constant frequency 1.0MHz PWM control scheme is employed in this IC, which means the tiny external components can be used. In fact, 1mm tall inductor and 0.22µF output capacitor for the typical application is very appropriate. Additionally, the schottky diode in boost circuit is integrated in this chip. AP3019 also provides a disable port to ease its use for different systems. Inherently Uniform LED Current High Efficiency up to 84% No Need for Extra Schottky Diode Over Output Voltage Protection Drives 2 to 5 LEDs Fast 1.0MHz Switching Frequency Uses Tiny 1mm Tall Inductor Requires Only 0.22µF Output Capacitor Applications · · · · · The over output voltage protection is equipped in AP3019. When any LED is broken or in other abnormal conditions, the output voltage will be clamped to 27V. Cellular Phones Digital Cameras LCD modules GPS Receivers PDAs, Handheld Computers The AP3019 is available in standard SOT-23-6 package. SOT-23-6 Figure 1. Package Type of AP3019 Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 1 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Pin Configuration K Package (SOT-23-6) VOUT 1 6 SW GND 2 5 VIN FB 3 4 CTRL Figure 2. Pin Configuration of AP3019 (Top View) Pin Description Pin Number Pin Name Function 1 SW 2 GND 3 FB 4 CTRL Shutdown and Dimming Pin. Connect to 1.8V or higher to enable device; Connect to 50mV or less to disable device; Connect to a voltage between 1.8V and 50mV to achieve linear dimming 5 VOUT Output Pin. Connected to the cathode of internal schottky diode 6 VIN Switch Pin. Connect external inductor Ground Pin Voltage Feedback. Reference voltage is 200mV Input Supply Pin. Must be locally bypassed Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 2 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Functional Block Diagram FB SW 3 1 5 SOFT START VIN 6 VREF 1.25 V 200 mV VOUT OVP DRIVER A1 A2 Q R Q1 S COMPARATOR Σ CTRL 2 4 GND RAMP GENERATOR 1.0 MHz OSCILLATOR Figure 3. Functional Block Diagram of AP3019 Ordering Information AP3019 - Circuit Type E1: Lead Free Package TR: Tape and Reel K: SOT-23-6 Package SOT-23-6 Temperature Range o -40 to 85 C Part Number Marking ID Packing Type AP3019KTR-E1 E9S Tape & Reel BCD Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant. Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 3 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit VIN 20 V SW Voltage 27 V FB Voltage 20 V CTRL Voltage 20 V 265 oC/W 150 oC TSTG -65 to 150 oC TLEAD 260 oC ESD (Machine Model) 250 V ESD (Human Body Model) 2000 V Input Voltage Thermal Resistance (Junction to Atmosphere, no Heat sink) RθJA Operating Junction Temperature Storage Temperature Range Lead Temperature (Soldering, 10sec) 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 oC Input Voltage VIN 2.5 16 V CTRL Voltage VCTRL 16 V Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 4 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Electrical Characteristics (VIN=3V, VCTRL =3V, TA=25oC, unless otherwise specified.) Parameter Symbol Minimum Operating Voltage VIN(min) Maximum Operating Voltage VIN(max) Conditions Min Typ Max Unit 2.5 V 16 IOUT=20mA, 4 LEDs, Feedback Voltage VFB FB Pin Bias Current IFB Supply Current ICC VFB=VIN, Not Switching Supply Current IQ VCTRL=0V TA=-40oC to 85oC 188 200 212 mV 35 100 nA 1.3 2.0 2.7 mA 2.0 3.2 5.0 µA 1.3 MHz Switching Frequency f 0.7 1.0 Maximum Duty Cycle DMAX 90 93 Switch Current Limit (Note 2) ILIMIT Switch VCE Saturation Voltage VCESAT Switch Leakage Current CTRL Pin Voltage VCTRL TA=25oC, D=40% 500 TA=25oC, D=80% 350 ISW=250mA 360 VSW=5V 0.01 High Schottky Forward Drop VDROP Schottky Leakage Current 5 µA V 55 TA=85oC 50 TA=-40oC 75 ID=150mA 0.7 VR=23V 0.1 VR=27V Soft Start Time mV 0.05 40 ICTRL mA 1.8 Low CTRL Pin Bias Current % 72 µA V 4 µA 150 t 300 µS Note 2: The Switch Current Limit is related to Duty Cycle. Please refer to Figure 16 for detail. Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 5 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Typical Performance Characteristics 85 85 84 84 Efficiency (%) Efficiency (%) (VF of WLED is 3.45V @ IF=20mA, unless otherwise noted ) 83 82 VIN=3.6V, IOUT=20mA, 4LEDS CIN=1µF, COUT=0.22µF, L=22µH 81 80 -50 -25 0 25 50 75 83 82 O IOUT=20mA, 4LEDS, TA=25 C CIN=1µF, COUT=0.22µF, L=22µH 81 80 2.5 100 3.0 o Junction Temperature ( C) 3.5 4.0 4.5 5.0 Input Voltage (V) Figure 4. Efficiency vs. Junction Temperature Figure 5. Efficiency vs. Input Voltage 85 350 300 Schottky Forward Current (mA) Efficiency (%) 84 83 82 O VIN=3.6V, IOUT=20mA, TA=25 C CIN=1µF, COUT=0.22µF, L=22µH 81 250 200 150 100 50 0 80 2 3 4 0 5 200 400 600 800 1000 Schottky Forward Drop (mV) LEDS (PCS) Figure 6. Efficiency vs. LED's Number Figure 7. Schottky Forward Current vs. Schottky Forward Drop Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 6 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Typical Performance Characteristics (Continued) 30 3.0 25 2.5 Supply Current (mA) Quiescent Current (µA) (VF of WLED is 3.45V @ IF=20mA, unless otherwise noted ) 20 15 10 2.0 1.5 1.0 O -50 C O 25 C O 100 C 5 0.5 0 2 4 6 8 10 12 14 16 0.0 Input Voltage (V) 0 2 4 6 8 10 12 14 16 Input Voltage (V) Figure 8. Shutdown Quiescent Current vs. Input Voltage Figure 9. Supply Current vs. Input Voltage 29.0 4.0 3.8 28.0 3.6 3.4 27.5 Input Current (mA) Output Clamp Voltage (V) 28.5 27.0 26.5 26.0 3.2 3.0 2.8 2.6 2.4 25.5 2.2 25.0 2 4 6 8 10 12 14 2.0 2.5 16 3.0 3.5 4.0 4.5 5.0 Input Voltage (V) Input Voltage (V) Figure 10. Output Clamp Voltage vs. Input Voltage Figure 11. Input Current in Output Open Circuit vs. Input Voltage Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 7 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Typical Performance Characteristics (Continued) (VF of WLED is 3.45V @ IF=20mA, unless otherwise noted ) 210 1.15 208 1.10 206 Feedback Voltage (V) 1.20 Frequency (MHz) 1.05 1.00 0.95 0.90 0.85 204 202 200 198 196 0.80 194 0.75 192 0.70 -50 -25 0 25 50 75 190 -50 100 -25 Figure 12. Switching Frequency 50 75 100 Figure 13. Feedback Voltage vs. Junction Temperature vs. Junction Temperature 0.50 0.78 0.45 Schottky Leakage Current (µA) 0.80 0.76 Schottky Forward Drop (V) 25 o Junction Temperature ( C) 0.74 0.72 0.70 0.68 0.66 0.64 VR=10V VR=16V VR=23V 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.62 0.60 -50 0 Junction Temperature ( C) o -25 0 25 50 75 0.00 -50 100 -25 0 25 50 75 100 o Junction Temperature ( C) o Junction Temperature ( C) Figure 14. Schottky Forward Drop vs. Junction Temperature Figure 15. Schottky Leakage Current vs. Junction Temperature Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 8 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Typical Performance Characteristics (Continued) (VF of WLED is 3.45V @ IF=20mA, unless otherwise noted ) 700 500 O -50 C O 25 C O 100 C 450 Saturation Voltage (mV) Current Limit (mA) 600 500 400 300 200 100 30 400 350 300 250 200 150 40 50 60 70 80 100 50 90 100 150 200 250 300 Switch Current (mA) Duty Cycle (%) Figure 17. Switch Saturation Voltage Figure 16. Switch Current Limit vs. Duty Cycle vs. Switch Current 250 Feedback Voltage (mV) 200 150 100 50 0 0.0 0.5 1.0 1.5 2.0 CTRL Voltage (V) Figure 18. Feedback Voltage vs. CTRL Pin Voltage Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 9 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Application Information R1 = Operation 200mV I LED The AP3019 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. Over Voltage Protection 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 It is clear that the voltage level at non-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. VIN ≥ 3V The AP3019 has an internal open-circuit protection circuit. When the LEDs are disconnected from circuit or fail open, the output voltage is clamped at 27V. The AP3019 will switch at a low frequency, and minimize input current. The AP3019 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 20. IIN 100mA/div VOUT 10V/div L1 VCTRL 2V/div VIN Control Signal SW Time 100µs/div VOUT C2 AP3019 CTRL C1 GND FB Figure 20. Soft Start Waveform VIN=3.6V, 4LEDS, ILED=20mA R1 Dimming Control Figure 19. Typical Application circuit to Decide R1 LED Current Control Refer to Figure 19, 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: Apr. 2007 Rev. 1. 1 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. (1). Adding a Control Signal to CTRL Pin There are three methods to control CTRL pin signal First, adding a PWM Signal to CTRL pin directly. The AP3019 is turned on or off by the PWN signal when it is applied on the CTRL pin. The typical frequency of BCD Semiconductor Manufacturing Limited 10 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Application Information (Continued) this PWM signal is 500Hz to 1KHz. Please refer to Figure 21. AP3019 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 24. CTRL 500Hz to 1KHz Figure 21. Dimming Control Using a PWM Signal in CTRL Pin AP3019 Secondly, adding a constant DC voltage through a resistor divider to CTRL pin can control the dimming. The FB voltage is indirectly adjusted when the CTRL pin voltage is between 50mV to 1.8V, which can be used as dimming control. Please refer Figure 22. R1 10K VDC 0.1 to 3.6V FB VDC R3 90K Figure 24. Dimming Control Using DC Voltage AP3019 CTRL Second, using a filtered PWM signal can do it. The filtered PWM signal can be considered as a varying and adjustable DC voltage. R2 10K Figure 22. Dimming Control Using a DC Voltage in CTRL Pin AP3019 Thirdly, using a filtered PWM signal adding to CTRL pin can achieve dimming control. The filtered PWM signal can be considered as an adjustable DC voltage. It will change the FB voltage indirectly and achieve dimming control. The circuit is shown in Figure 23. R 5K PWM R1 10Ω R2 5K Effective Feedback Voltage FB PWM R4 10K C R3 0.1µF 90K Effective Feedback Voltage R2 5K R1 10Ω Figure 25. Dimming Control Using a Filtered PWM Voltage AP3019 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. CTRL C 100nF Figure 23. Dimming Control Using a Filtered PWM Signal Voltage in CTRL Pin (2). Changing the Effective Feedback Voltage There are three methods to change the effective feedback voltage. Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 11 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Application Information (Continued) AP3019 FB Logic Signal Effective Feedback Voltage R2 2N7002 R1 Figure 26. Dimming Control Using Logic Signal Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 12 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 Typical Application VIN ≥ 3V 10µΗ VIN Control Signal SW VOUT AP3019 CTRL GND 0.22µF FB 1µF 10Ω C: X5R or X7R Dielectric L: SUMIDA CDRH5D28R-100NC or Equivalent This circuit can work in full temperature A. Four White LEDs Driver VIN ≥ 3V 22µΗ VIN Control Signal SW VOUT AP3019 CTRL GND 0.22µF FB 1µF 10Ω C: X5R or X7R Dielectric L: SUMIDA CDRH5D28R-220NC or Equivalent This circuit can work in full temperature B. Five White LEDs Driver Figure 27. Typical White LED Drivers Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 13 Preliminary Datasheet WHITE LED STEP-UP CONVERTER AP3019 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) 5 0.300(0.012) 0.600(0.024) 4 1.500(0.059) 1.700(0.067) 2.650(0.104) 2.950(0.116) 6 0.200(0.008) 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) 1.050(0.041) 1.050(0.041) 1.150(0.045) 1.250(0.049) Apr. 2007 Rev. 1. 1 BCD Semiconductor Manufacturing Limited 14 http://www.bcdsemi.com IMPORTANT NOTICE BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifications herein. 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