AP8802 1A LED Step-Down Converter General Description Features • • • • • • • • LED driving current up to 1A High efficiency up to 92% Operating input voltage up to 48V High switching frequency up to 500kHz PWM/DC input for dimming control Built-in output open-circuit protection SOP-8L, SOP-8L-EP (Preview) and DFN3030-10 are available in “Green” Molding Compound (No Br, Sb) Lead Free Finish/RoHS Compliant (Note 1) The AP8802 is a step-down DC/DC converter designed to drive LEDs with a constant current. The device can drive up to thirteen LEDs, depending on the forward voltage of the LEDs, in series from a voltage source of 8V to 48V. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The AP8802 switches at frequency up to 500kHz. This allows the use of small size external components, hence minimizing the PCB area needed. Maximum output current of AP8802 is set via an external resistor connected between the VIN and SET input pins. Dimming is achieved by applying either a DC voltage or a PWM signal at the CTRL input pin. An input voltage of 0.2V or lower at CTRL shuts down the output at SW and puts the device into a low-current standby state. Applications • • • • Commercial & industrial lighting Small LCD panel backlight Appliances interior lighting Architecture Detail lighting Ordering Information AP 8802 XX G - X Package Green Packing S : SOP-8L SP : SOP-8L-EP (Preview) FN : DFN3030-10 G : Green 7/ 13 : Tape & Reel Device AP8802SG-13 AP8802SPG-13 AP8802FNG-7 Notes: Package Code Packaging (Note 2) S SP FN SOP-8L SOP-8L-EP DFN3030-10 7”/13” Tape and Reel Quantity Part Number Suffix 2500/Tape & Reel 2500/Tape & Reel 3000/Tape & Reel -13 -13 -7 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied, see EU Directive 2002/95/EC Annex Notes. 2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf. AP8802 Rev. 1 1 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Pin Assignments (1) SOP-8L (2) SOP-8L-EP (Preview) 2 GND NC 3 AP8802 VIN 4 8 CTRL 7 GND 6 5 SW SW SET 1 GND NC 2 Pr ev i SET 1 ew ( Top View ) ( Top View ) 3 VIN 4 AP8802 8 CTRL 7 GND 6 5 SW SW (3) DFN3030-10 ( Top View ) SET 1 10 CTRL GND 2 9 GND NC 3 8 NC NC 4 7 SW VIN 5 6 SW AP8802 Pin Descriptions Pin Name SW Description Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI. GND GND pin SET Set Nominal Output Current Pin. Configure the output current of the device. CTRL Dimming and On/Off Control Input. Input voltage of 0.2V or lower forces the device into low current standby mode and shut off the output. A PWM signal allows the output current to be adjusted above or below the level set by the resistor connected to SET input pin. The input impedance is about 50kΩ, and if the pin is left open VCTRL = VREF VIN Input Supply Pin. Must be locally bypassed. NC No connection AP8802 Rev. 1 2 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Block Diagram SET SW VIN Voltage Regulator Comparator CTRL 5V Sensing Block PWM/DC Control AP8802 VREF 1.25V R GND Figure 1: AP8802 block diagram Absolute Maximum Ratings Symbol Parameter Rating Unit V VIN VIN pin voltage -0.3~50 VSW SW voltage -0.3~50 TJ TLEAD TST 150 C 300 o C -65 to +150 o C Junction Temperature Lead Temperature Soldering Storage Temperature Range V o Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must therefore not be exceeded under any condition. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling and transporting these devices Recommended Operating Conditions Symbol TA AP8802 Rev. 1 Parameter Ambient Temperature Range 3 of 13 www.diodes.com Min -40 Max 105 Unit ºC MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Electrical Characteristics Symbol VIN IOUT IQ FOSC VTHD VREF SET Rds(on) EN EN Parameter Operating Input Voltage Continuous switch current Quiescent Current Switching Frequency Internal Threshold Voltage Internal Reference Voltage SET pin input current On Resistance of MOSFET Switch leakage current Voltage High Voltage Low θJA Thermal Resistance Junction-to-Ambient θJC Thermal Resistance Junction-to-Case ISW Leakage Notes: o (VIN =12V, TA=25 C, unless otherwise specified) Conditions Min 8.0 Typ. - 184 - 75 200 1.25 5 0.65 82 TBD 38 52 TBD 24 (Note 3) VSET=VIN-0.2 ISW=0.8A ON OFF SOP-8L (Note 4) SOP-8L-EP (Preview)(Note 4) DFN3030-10 (Note 4) SOP-8L (Note 4) SOP-8L-EP (Preview)(Note 4) DFN3030-10 (Note 4) 1.25 - Max 48 1 120 0.5 216 1.1 8 0.2 - Unit V A μA MHz mV V μA Ω μA V V °C/W °C/W °C/W °C/W °C/W °C/W 3. Refer to figure 7 for the device derating curve. 4. Test condition for SOP-8L, SOP-8L-EP (Preview) and DFN3030-10: Device mounted on FR-4 PCB, 2”x2”, 2oz copper, minimum recommended pad layout on top layer and thermal vias to bottom layer ground plane. For better thermal performance, larger copper pad for heat-sink is needed. Typical Application Circuit Figure 2: Typical Application Circuit AP8802 Rev. 1 4 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Application Information LED Current Control The LED current is controlled by the resistor RSET in Figure 2. Connected between VIN and SET the nominal average output current in the LED(s) is defined as: ILED = VTHD RSET If the CTRL pin is driven by an external voltage (lower than 2.5V), the average LED current is: ILED = VCTRL VTHD VREF RSET LED current Versus RSET and VCTRL 1200 LED Current [mA] 1000 0.2 0.39 LED current @ VCTRL = 1.25V 0.47 800 0.56 0.33 600 0.2 0.39 0.82 0.47 0.56 0.68 0.33 400 0.47 200 LED current @ VCTRL = 2.5V 0.68 1 0.82 1 0.68 0.82 1 LED current @ VCTRL = 0.625V 1.2 1.5 1.2 1.2 2 1.5 1.5 0 0 2 2 0.15 0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5 1.65 1.8 1.95 2.1 2.25 2.4 2.55 2.7 2.85 3 3 3 3 RSET value [Ohms] Figure 3: LED Current setting Vs RSET and VCTRL AP8802 Rev. 1 5 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Application Information (Continued) Inductor Selection This section highlights how to select the inductor suitable for the application requirements, in terms of switching frequency, LED current accuracy and temperature. Switching Frequency @ ILED = 700mA 500 68 450 400 Frequency [kHz] 100 47 350 300 68 12V - 3 LEDs 150 250 24V - 5 LEDs 100 200 48V - 10 LEDs 220 150 100 150 47 68 50 470 220 100 150 470 470 220 0 0 50 100 150 200 250 300 350 400 450 500 Inductor Value [uH] Figure 4: Switching Frequency Vs Inductor Value The inductor influences the LED current accuracy that the system is able to provide. The following section highlights how to select the inductor in relation to the device packages and the LED current, while maintaining the chip temperature below 70˚C. AP8802 Rev. 1 6 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Application Information (Continued) AP8802 DFN3030-10 Minimum Recommended Inductor - LED Current 1A 8% Accuracy, <70°C Case Temperature 12 Legend 11 47µH 68µH 10 100µH 9 150µH Number of LEDs 220µH 8 470µH 7 150uH 6 5 100uH 4 3 68uH 2 1 0.00 47uH 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 Supply Voltage (V) Figure 5: DFN3030-10 recommended inductor with 1A LED current AP8802 SOP-8L Minimum Recommended Inductor 8% Accuracy, <70°C Case Temperature 12 Legend 11 47µH 68µH 10 100µH 9 150µH Number of LEDs 220µH 8 470µH 7 470uH 6 220uH 5 150uH 4 100uH 3 2 68uH 47uH 1 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 Supply Voltage (V) Figure 6: SOP-8L recommended inductor with 700mA LED current AP8802 Rev. 1 7 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Application Information (Continued) Capacitor Selection The small size of ceramic capacitors makes them ideal for AP8802 applications. X5R and X7R types are recommended because they retain their capacitance over wider voltage and temperature ranges than other types such as Z5U. A 2.2μF input capacitor is sufficient for most intended applications of AP8802. A 4.7μF input capacitor is suggested for application with an input voltage equal or higher than 40V. Diode Selection Schottky diodes, e.g. B2100 or B1100, with their low forward voltage drop and fast reverse recovery, are the ideal choice for AP8802 applications. PWM Dimming A Pulse Width Modulated (PWM) signal with a max resolution of 8bit, can be applied to the CTRL pin to change the output current to a value above or below the nominal average value set by resistor RSET. To achieve this resolution the PWM frequency has to be lower than 500Hz. Thermal Considerations The graph below in figure 7, gives details for power derating. This assumes the device to be mounted on a 25x25mm PCB with 1oz copper standing in still air. Maximum Power Dissipation 3 2.8 2.6 2.4 2.2 DFN3030-10 2 Power (W) 1.8 1.6 1.4 1.2 SOP8L 1 0.8 0.6 0.4 0.2 0 0 25 50 75 100 125 150 Ambient Temperature (Deg C) Figure 7: AP8802 derating curves Package Selection The device comes with a wide selection of packages. The suggested package is able to provide a case temperature below 70˚C (with an ambient temperature of 25˚C) for the combination of input voltage and load requested. AP8802 Rev. 1 8 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Application Information (Continued) AP8802 - suggested package @ ILED=1A and 100µH Inductor 12 LEDs 11 LEDs 10 LEDs 9 LEDs 8 LEDs 7 LEDs 6 LEDs 5 LEDs 4 LEDs 3 LEDs 2 LEDs 1 LED SOP-8L-EP DFN3030-10 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 SOP-8L ÷ SOP-8L-EP ÷ DFN3030-10 Vin Figure 8: Suggested package for a 1A application AP8802 - suggested package @ ILED=700mA and 100µH Inductor 12 LEDs 11 LEDs 10 LEDs 9 LEDs 8 LEDs 7 LEDs 6 LEDs 5 LEDs 4 LEDs 3 LEDs 2 LEDs 1 LED SOP-8L-EP DFN3030-10 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 SOP-8L SOP-8L-EP DFN3030-10 Vin Figure 9: Suggested package for a 700mA application AP8802 Rev. 1 9 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Marking Information (1) SOP-8L ( Top View ) 5 8 Logo Part Number AP8802 YY WW X X 1 G : Green YY : Year : 08, 09,10~ WW : Week : 01~52; 52 represents 52 and 53 week X : Internal Code 4 (2) SOP-8L-EP (Preview) ( Top View ) 5 8 Logo Part No. AP8802 YY WW X X E 1 G : Green YY : Year : 08, 09,10~ WW : Week : 01~52; 52 represents 52 and 53 week X : Internal Code SOP-8L-EP 4 (3) DFN3030-10 ( Top View ) XX YW X Part Number AP8802FNG-7 AP8802 Rev. 1 XX : Identification Code Y : Year : 0~9 W : Week : A~Z : 1~26 week; a~z : 27~52 week; z represents 52 and 53 week X : A~Z : Green Package DFN3030-10 10 of 13 www.diodes.com Identification Code A5 MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Package Information (All Dimensions in mm) 0.254 0.10/0.20 3.85/3.95 5.90/6.10 (1) Package Type: SOP-8L Gauge Plane Seating Plane 0.62/0.82 Detail "A" 7°~9° 7°~9° 0.15/0.25 1.30/1.50 1.75max. 0.35max. 45° Detail "A" 0°/8° 0.3/0.5 1.27typ 4.85/4.95 5.4 8x-0.60 8x-1.55 6x-1.27 Land Pattern Recommendation (Unit: mm) (2) Package Type: SOP-8L-EP (Preview) Detail "A" 0°/8° Exposed pad 2.4Ref. 3.70/4.10 45° 0.35max. 3.85/3.95 5.90/6.10 7°~9° 7°~9° 1 1 0.15/0.25 1.75max. 1.30/1.50 3.3Ref. Bottom View 0/0.13 0.254 0.3/0.5 1.27typ 4.85/4.95 1 Gauge Plane Seating Plane 0.62/0.82 Detail "A" 8x-0.60 5.4 Exposed pad 8x-1.55 6x-1.27 Land Pattem Recommendation (Unit:mm) AP8802 Rev. 1 11 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Package Information (Continued) (3) Package Type: DFN3030-10 0.15Typ. 0/0.05 Seating Plane Side View 2X- 0.25 A 0.08 C 0.57/0.60 TOP MARK 0.10 C C 2.9/3.1 2.3/2.5 B A R0 .30 0 0.25/0.55 2.9/3.1 1.5/1.7 (Pin #1 ID) 2X- 0.25 B 0.375Typ. 0.50Typ. 0.2/0.3 0.10 C A B Bottom View AP8802 Rev. 1 12 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated AP8802 1A LED Step-Down Converter Taping Orientation For DFN3030-10 Notes: 5. The taping orientation of the other package type can be found on our website at http://www.diodes.com/datasheets/ap02007.pdf. IMPORTANT NOTICE Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to any product herein. Diodes Incorporated does not assume any liability arising out of the application or use of any product described herein; neither does it convey any license under its patent rights, nor the rights of others. The user of products in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on our website, harmless against all damages. LIFE SUPPORT Diodes Incorporated products are not authorized for use as critical components in life support devices or systems without the expressed written approval of the President of Diodes Incorporated. AP8802 Rev. 1 13 of 13 www.diodes.com MARCH 2009 © Diodes Incorporated