AP8802H

AP8802H 60V 1A LED Step-down Converter Description The AP8802H 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 60V. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The AP8802H switches at frequency up to Pin Assignments (Top View) SET 1 GND NC 2 3 AP8802H 8 7 6 5 SO-8-EP CTRL GND SW SW N EW PRODUCT P RELIMINARY 500kHz. This allows the use of small size external components, hence minimizing the PCB area needed. Maximum output current of AP8802H 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. • • • • • • • • • • • • • LED driving current up to 1A High efficiency up to 92% Operating input voltage up to 60V 5% nominal accuracy High switching frequency up to 500kHz PWM/DC input for dimming control Built-in output open-circuit protection SO-8-EP is available in “Green” Molding Compound (No Br, Sb) Lead Free Finish/ RoHS Compliant (Note 1) VIN 4 Applications Commercial & industrial lighting Small LCD panel backlight Appliances interior lighting Architecture Detail lighting Features Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at http://www.diodes.com/products/lead_free.html. AP8802H Document number: DS32227 Rev. 1 - 2 1 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Typical Application Circuit 48V VIN CTRL SET RSET = 0.2 ohm N EW PRODUCT P RELIMINARY D1 AP8802H C1 = 2.2µF GND SW L1 = 100µH Pin Descriptions Pin Name SW GND SET Description Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI. GND pin Set Nominal Output Current Pin. Configure the output current of the device. Dimming and On/Off Control Input. Input voltage of 0.2V or lower forces the device into low current standby mode and shuts 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 Input Supply Pin. Must be locally bypassed. No connection CTRL VIN NC AP8802H Document number: DS32227 Rev. 1 - 2 2 of 11 www.diodes.com 1 June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Functional Block Diagram SET SW VIN Sensing Block Comparator N EW PRODUCT P RELIMINARY Voltage Regulator 5V CTRL PWM/DC Control VREF 1.25V AP8802H R GND Figure 2: AP8802H Block Diagram Absolute Maximum Ratings Symbol VIN VSW TJ TLEAD TST Caution: Parameter VIN pin Voltage SW Voltage Junction Temperature Lead Temperature Soldering Storage Temperature Range Rating -0.3~60 -0.3~60 150 300 -65 to +150 Unit V V °C °C °C 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 (Note 2) Symbol TA Duty Cycle Notes: Parameter Ambient Temperature Range Using Inductor ≥ 100µH (Note 2) Min -40 0.1 Max 105 0.95 Unit ºC 2. For most applications the LED current will be within 5% over the duty cycle range specified. Duty cycle accuracy is also dependent on propagationdelay. Smaller size inductors can be used but LED current accuracy may be greater than 5% at extremes of duty cycle. This is most noticeable at low duty cycles (less than 0.1) or when the input voltage is high and only one LED is being driven. AP8802H Document number: DS32227 Rev. 1 - 2 3 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Electrical Characteristics (VIN =12V, TA=25oC, unless otherwise specified) Symbol VIN IOUT IQ FOSC VTHD VREF SET Rds(on) ISW_Leakage 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 Thermal Resistance Junctionto-Ambient Thermal Resistance Junctionto-Case Conditions (Note 3) 190 1.25 75 200 1.25 5 0.65 45 7 Min 8.0 Typ. Max 60 1 120 0.5 210 1.1 8 0.2 Unit V A μA MHz mV V μA Ω μA V V °C/W °C/W N EW PRODUCT P RELIMINARY VSET = VIN-0.2 ISW = 0.8A ON OFF SO-8-EP (Note 4) SO-8-EP (Note 4) θJA θJC Notes: 3. Refer to figure 8 for the device derating curve. 4. Test condition for SO-8-EP: 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. AP8802H Document number: DS32227 Rev. 1 - 2 4 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Applications Information LED Current Control The LED current is controlled by the resistor RSET in Figure 1 connected between VIN and SET. The nominal average output current in the LED(s) is defined as: V ILED = THD RSET N EW PRODUCT P RELIMINARY 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 0.39 0.47 0.56 600 0.2 400 0.33 0.39 0.47 0.56 0.68 0.33 0.47 0.68 0.82 1 0.82 1 1.2 1.5 1.2 1.2 2 1.5 1.5 2 2 3 3 3 3 LED current @ VCTRL = 1.25V LED current @ VCTRL = 2.5V LED current @ VCTRL = 0.625V 1000 LED Current [mA] 0.2 800 200 0.68 0.82 1 0 0 RSET value [Ohms] 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 Figure 3: LED Current setting Vs RSET and VCTRL AP8802H Document number: DS32227 Rev. 1 - 2 5 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Applications 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 500 450 400 350 Frequency [kHz] 300 250 200 150 100 50 0 0 50 100 150 200 250 300 350 400 450 Inductor Value [uH] 47 68 100 150 220 150 220 470 470 470 500 100 47 100 12V - 3 LEDs 24V - 5 LEDs 220 48V - 10 LEDs 68 N EW PRODUCT P RELIMINARY 68 150 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. AP8802H Document number: DS32227 Rev. 1 - 2 6 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Applications Information (Continued) AP8802H SO-8-EP Minimum Recommended Inductor 15 14 13 12 11 Legend 47µH 68µH 100µH 150µH 5% Accuracy, TC < 70°C ILED ~ 1A N EW PRODUCT P RELIMINARY Number of LEDs 10 9 8 7 6 5 4 3 2 1 0 10 20 30 40 50 60 47µH 68µH 100µH 150µH Supply Voltage (V) Figure 5: SO-8-EP recommended inductor with 1A LED current AP8802H Document number: DS32227 Rev. 1 - 2 7 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Applications Information (Continued) Capacitor Selection The small size of ceramic capacitors makes them ideal for AP8802H 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 AP8802H. A 4.7μF input capacitor is suggested for application with an input voltage equal or higher than 60V. Diode Selection N EW PRODUCT P RELIMINARY Schottky diodes, e.g. B2100 or B1100, with their low forward voltage drop and fast reverse recovery, are the ideal choice for AP8802H 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 8, 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 2.4 2.2 2 1.8 1.6 P ower (W) 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 25 50 75 A mbient temperature (°C) 100 125 Figure 8: AP8802H 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. AP8802H Document number: DS32227 Rev. 1 - 2 8 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Ordering Information AP8802H SP - 13 Package SP : SO-8-EP Device Package Code SP Packaging (Note 5) SO-8-EP Packing 13 : Tape & Reel 13” Tape and Reel Quantity Part Number Suffix 2500/Tape & Reel -13 N EW PRODUCT P RELIMINARY AP8802HSP-13 Notes: 5. 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. Marking Information (1) SO-8-EP ( Top View ) 8 5 Logo Part No. AP8802H YY WW X X E 1 4 A~Z : Internal code YY : Year : 08, 09,10~ WW : Week : 01~52; 52 represents 52 and 53 week X : Internal Code SO-8-EP AP8802H Document number: DS32227 Rev. 1 - 2 9 of 11 www.diodes.com June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter Package Outline Dimensions (All Dimensions in mm) (1) Package Type: SO-8-EP Detail "A" Exposed pad 7°~9° 3.85/3.95 5.90/6.10 3.70/4.10 45° 0.35max. N EW PRODUCT P RELIMINARY 7°~9° 1 1.30/1.50 1.75max. 0.15/0.25 3.3Ref. 1 Bottom View 0/0.13 0.254 1.27typ 4.85/4.95 1 0.3/0.5 Gauge Plane Seating Plane 0.62/0.82 Detail "A" 8x-0.60 Exposed pad 6x-1.27 8x-1.55 Land Pattem Recommendation (Unit:mm) 5.4 AP8802H Document number: DS32227 Rev. 1 - 2 10 of 11 www.diodes.com 2.4Ref. June 2010 © Diodes Incorporated AP8802H 60V 1A LED Step-down Converter IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. 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