WHITE LED STEP-UP CONVERTER. Features

Transcription

1 General Description The 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 1.0MHz 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. The also provides a disable pin to ease its use for different systems. The output over-voltage protection is implemented in. When any LED is broken or in other abnormal conditions, the output voltage will be clamped. Features Inherently Uniform LED Current High Efficiency up to 84% No Need for External Schottky Diode Output Over-voltage Protection (OVP) Fixed 1.0MHz Switching Frequency Uses Tiny 1mm Tall Inductor Requires Only 0.22µF Output Capacitor High Frequency Dimming Control Applications Cellular Phones Digital Cameras LCD Modules GPS Receivers PDAs, Handheld Computers The is available in standard SOT-23-6 and TSOT-23-6 packages. SOT-23-6 TSOT-23-6 Figure 1. Package Types of 1

2 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 (Top View) Pin Description Pin Number Pin Name Function 1 SW Switch pin. Connect external inductor 2 GND Ground 3 FB 4 CTRL Voltage feedback pin. The reference voltage is 200mV for AP3036 and 250mV for AP3036A Shutdown and dimming pin. Connect to 1.8V or higher to enable device; Connect to 0.4V 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 Input supply pin. Must be connected to a local bypass capacitor 2

3 Functional Block Diagram Ordering Information Figure 3. Functional Block Diagram of AP Circuit Type G1: Green Blank: AP3036 A: AP3036A TR: Tape & Reel Package K: SOT-23-6 KT: TSOT-23-6 Package SOT-23-6 TSOT-23-6 Temperature Range -40 to 85 C Part Number Marking ID Packing Type AP3036KTR-G1 GHI Tape & Reel AP3036AKTR-G1 GJE Tape & Reel AP3036KTTR-G1 L2C Tape & Reel AP3036AKTTR-G1 L3C Tape & Reel BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant and green. 3

4 Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit Input Voltage 20 V SW Pin Voltage V SW 38 V Feedback Voltage V FB 20 V CTRL Pin Voltage V CTRL 20 V Thermal Resistance (Junction to Ambient, No Heat Sink) θ JA 265 C/W Operating Junction Temperature T J 150 C Storage Temperature Range T STG -65 to 150 C Lead Temperature (Soldering, 10sec) T LEAD 260 C ESD (Machine Model) 250 V ESD (Human Body Model) 2000 V 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 T OP C Input Voltage V CTRL Pin Voltage V CTRL 16 V 4

5 Electrical Characteristics =3V, V CTRL =3V, T A =25 C, unless otherwise specified. Parameter Symbol Conditions Min Typ Max Unit Minimum Operating Voltage (Min) 2.5 V Maximum Operating Voltage (Max) 16 Feedback Voltage V FB AP I OUT =20mA, 4 LEDs mv AP3036A FB Pin Bias Current I FB na Quiescent Current I Q V FB =, No ma Switching Shutdown Quiescent Current I SHDN V CTRL =0V µa Switching Frequency f 1.0 MHz Maximum Duty Cycle D MAX % Switch Current Limit (Note 2) I LIMIT D=40% or 80% 550 ma Switch V CE Saturation Voltage V CESAT I SW =250mA 360 mv Switch Leakage Current V SW =5V µa CTRL Pin Voltage V CTRL High 1.8 Low 0.4 V CTRL Pin Bias Current I CTRL 100 µa OVP Voltage V OV 30 V Schottky Forward Drop V DROP I D =150mA 0.7 V Schottky Leakage Current V R (Reverse Voltage)=23V V R (Reverse Voltage)=27V Soft Start Time t 100 µs 150 µa Thermal Resistance (Junction to Case) θ JC SOT TSOT C/W Note 2: The switch current limit is related to duty cycle. Please refer to Figure 16 for detail. 5

6 Typical Performance Characteristics The WLED forward voltage (V F ) is 3.45V at I F =20mA, unless otherwise noted. 90 Efficiency (%) =3.6V I OUT =20mA Schottky Forward Voltage (mv) LED Numbers Schottky Forward Current (ma) Figure 4. Efficiency vs. LED s Number Figure 5. Schottky Forward Voltage vs. Schottky Forward Current V CRTL =0V 3.6 V FB =1.0V Shutdown Current (µa) Quiescent Current (ma) Input Voltage (V) Input Voltage (V) Figure 6. Shutdown Current vs. Input Voltage Figure 7. Quiescent Current vs. Input Voltage 6

7 Typical Performance Characteristics (Continued) The WLED forward voltage (V F ) is 3.45V at I F =20mA, unless otherwise noted =3.6V Feedback Voltage (mv) =3.6V, 5 LEDs AP3036 AP3036A Current Limit (ma) Temperature ( O C) Temperature ( O C) Figure 8. Feedback Voltage vs. Temperature Figure 9. Current Limit vs. Temperature =V CRTL =3.6V 1.2 =3.6V, 5 LEDs Rising Down Saturation Voltage (mv) CTRL Voltage (V) Switch Current (ma) Temperature ( O C) Figure 10. Saturation Voltage vs. Switch Current Figure 11. CTRL Pin Voltage vs. Temperature 7

8 Typical Performance Characteristics (Continued) The WLED forward voltage (V F ) is 3.45V at I F =20mA, unless otherwise noted. 36 OVP Voltage (V) =V CRTL =3.6V Operating Frequency (MHz) =3.6V 5 LEDs Temperature ( O C) Temperature ( O C) Figure 12. OVP Voltage vs. Temperature Figure 13. Operating Frequency vs. Temperature =3.6V 5 LEDs Efficiency (%) Efficiency (%) I LED =20mA 8 LEDs Input Voltage (V) Output Current (ma) Figure 14. Efficiency vs. Input Voltage Figure 15. Efficiency vs. Output Current 8

9 Typical Performance Characteristics (Continued) The WLED forward voltage (V F ) is 3.45V at I F =20mA, unless otherwise noted =3.6V, 5 LEDs PWM Frequency=0.5kHz 25 =3.6V, 5 LEDs PWM Frequency=100KHz LED Current (ma) LED Current (ma) Duty (%) Duty (%) Figure 16. LED Current vs. Duty Figure 17. LED Current vs. Duty V CTRL 2V/div 2V/div V SW 10V/div V SW 10V/div V OUT 10V/div V OUT 10V/div I L 100mA/div I LED 10mA/div Time 40µs/div Time 10ms/div Figure 18. Powering On Figure 19. PWM Dimming ( =3.6V, V CTRL =2.5V, I LED =20mA, 5 LEDs) ( =3.6V, V PWM =2.5V, f PWM =0.5kHz, Duty=50%, 5 LEDs) 9

10 Typical Performance Characteristics (Continued) The WLED forward voltage (V F ) is 3.45V at I F =20mA, unless otherwise noted. 2V/div V SW 10V/div V OUT1 (AC) 100mV/div I L 100mA/div 2V/div V SW 10V/div V OUT 10V/div I LED 10mA/div Time 1µs/div Time 10µs/div Figure 20. Output Voltage Ripple Figure 21. PWM Dimming ( =V CTRL =3.6V, I LED =20mA, 5 LEDs) ( =3.6V, V PWM =2.5V, f PWM =100kHz, Duty=50%, 5 LEDs) 10

11 Typical Application Figure 22. Typical Application of (Note 3) Note 3: C: X5R or X7R type dielectric, L: SUMIDA CDRH5D28R-220NC or equivalent. And, this circuit can work in full temperature. 11

12 Mechanical Dimensions SOT-23-6 Unit: mm(inch) 2.820(0.111) 3.020(0.119) 0.300(0.012) 0.400(0.016) (0.008) (0.012) 0.600(0.024) Pin 1 Dot by Marking (0.028)REF 0.950(0.037)TYP 1.800(0.071) 2.000(0.079) 0.000(0.000) 0.150(0.006) 0.100(0.004) 0.200(0.008) 0.900(0.035) 1.300(0.051) 1.450(0.057) MAX 12

13 Mechanical Dimensions (Continued) TSOT-23-6 Unit: mm(inch) 2.800(0.110) 3.000(0.118) R0.100(0.004) MIN (0.059) 1.700(0.067) Pin 1 Dot by Marking 2.600(0.102) 3.000(0.118) 0.370(0.015) MIN 0.950(0.037) BSC 0.100(0.004) 0.250(0.010) 1.900(0.075) BSC GAUGE PLANE 0.250(0.010) BSC 0.700(0.028) 0.900(0.035) 1.000(0.039) MAX 0.000(0.000) 0.100(0.004) 0.350(0.014) 0.510(0.020) 13

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