PAM2803AAF095

A Product Line of Diodes Incorporated PAM2803 3W HIGH POWER WHITE LED DRIVER Description Pin Assignments The PAM2803 is a step-up DC-DC converter that delivers a regulated output current. The device switches at a 1.0MHz constant frequency, allowing for the use of small value external inductor and ceramic capacitors. The PAM2803 is targeted to be used for driving loads up to 1A from a two-cell alkaline battery. The LED current can be programmed by the external current sense resistor, RS, connected between the feedback pin (FB) and ground. A low 95mV feedback voltage reduces the power loss in the Rs for better efficiency. With its internal 2A, 100mΩ NMOS switch, the device can provide high efficiency even at heavy load. During the shutdown mode, the feedback resistor RS and the load are completely disconnected and the current consumption is reduced to less than 1µA. The PAM2803 is available in the 6-lead SOT23-6 package. Features Applications            White LED Torch (Flashlight)      White LED Camera Flash DSC (Digital Still Camera) Flash Cellular Camera Phone Flash PDA Camera Flash Camcorder Torch (Flashlight) Lamp LED Power Efficiency: up to 90% Current Accuracy: 5%(VIN = 3.6V to 1.8V @VF = 3.7V) Low Start-Up Voltage: 0.9V (ILED = 270mA) Low Hold Voltage: 0.75 (ILED = 200mA) 1MHz Switching Frequency Uses Small, Low Profile External Components Low RDS(ON): 100mΩ (typ) Over Temperature Protection Low Profile SOT23-6 Package Pb-Free Package Typical Applications Circuit ILED = 750mA, RS = 0.127Ω PAM2803 Document number: DS36400 Rev. 2 - 2 1 of 9 www.diodes.com December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 Pin Description Pin Number Pin Name Function 1 2 3 4 FB Feedback SHDN Shut Down 5 6 VOUT VIN Output Input SW Switch GND Ground Block Diagram Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. Parameter Input Pin Voltage SW Pin Voltage SHDN, FB Pin Voltage Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering, 5 sec) Rating -0.3 to +6 -0.3 to +6 -0.3 to +6 -40 to +85 -65 to +125 300 Unit V °C Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.) Parameter Rating Junction Temperature -40 to +125 Ambient Temperature -40 to +85 PAM2803 Document number: DS36400 Rev. 2 - 2 2 of 9 www.diodes.com Unit °C December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 Thermal Information Symbol Package Max Thermal Resistance (Junction to Case) Parameter θJC SOT23-6 130 Thermal Resistance (Junction to Ambient) θJA SOT23-6 250 Internal Power Dissipation PD SOT23-6 400 Unit °C/W mW Electrical Characteristics (@TA = +25°C, VIN = 2.4V, ILED = 750mA, VSHDN = VIN, L = 2.2µH, CIN = 10µF, CO = 10µF, unless otherwise specified.) Parameter Input Voltage Range Feedback Voltage Symbol Test Conditions  VIN  VFB Min Typ Max Units  VF-0.2 (Note 1) V 90 95 100 mV  0.9  V 0.75  V 0.85 1.0 1.15 MHz V 0.9 Start-Up Voltage VSTART VIN: 0V – 3V, ILED = 370mA Hold Voltage VHOLD VIN: 3V – 0V, ILED: 750mA – 200mA Oscillator Frequency FOSC SHDN Input High VSH VIN = 1.8V 1.0   SHDN Input Low VSL VIN = 1.8V   0.4 V Over Temperature Shutdown OTS   150  °C OTH   15  °C IO(MAX)  750   mA 1 3 mA 1 µA 0.1  Ω Over Temperature Hysteresis Maximum Output Current Range Quiescent Current Shutdown Current Switch On Resistance Current Limit Efficiency Note:  IQ ILED = 0mA, VO = 3.4V, Device Switching @ 1MHz  ISD Shutdown Mode  RDS(ON) VO = 3.4V  ILIM VO = 3.4V 2   A ILED = 750mA  90  % η 1. VF – LED forward voltage. PAM2803 Document number: DS36400 Rev. 2 - 2 3 of 9 www.diodes.com December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 Typical Performance Characteristics (@TA = +25°C, L = 2.2µF, CIN = 10µF, CO = 10µF, unless otherwise specified.) PAM2803 Document number: DS36400 Rev. 2 - 2 4 of 9 www.diodes.com December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 Typical Performance Characteristics (cont.) @TA = +25°C, L = 2.2µF, CIN = 10µF, CO = 10µF, unless otherwise specified.) PAM2803 Document number: DS36400 Rev. 2 - 2 5 of 9 www.diodes.com December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 Application Information Inductor Selection The PAM2803 can use small value inductors due to its switching frequency of 1MHz. The value of inductor will focus in the range of 2.2µH to 4.7µH for most PAM2803 applications. In typical high current white LED applications, it is recommended to use a 4.7µH inductor. The inductor should have low DCR (DC resistance) to minimize the I2R power loss, and it requires a current rating of 2A to handle the peak inductor current without saturating. Capacitor Selection An input capacitor is required to reduce the input ripple and noise for proper operation of the PAM2803. For good input decoupling, Low ESR (equivalent series resistance) capacitors should be used at the input. At least 2.2µF input capacitor is recommended for most applications. A minimum output capacitor value of 6.8µF is recommended under normal operating conditions, while a 10µF-22µF capacitor may be required for higher power LED current. A reasonable value of the output capaci tor depends on the LED current. The ESR of the output capacitor is the important parameter to determine the output voltage ripple of the converter, so low ESR capacitors should be used at the output to reduce the output voltage ripple. The small size of ceramic capacitors is an excellent choice for PAM2803 applications. The X5R and X7R types are preferred because they maintain capacitance over wide voltage and temperature ranges. Diode Selection It's indispensable to use a Schottky diode rated at 2A with the PAM2803. Using a Schottky diode with a lower forward voltage drop is better to improve the power LED efficiency, and its voltage rating should be greater than the output voltage. In application, the ON Semi conductor MBRA210LT3G is recommended. LED Current Setting The LED current is set by the single external RS resistor connected to the FB pin as shown in the typical application circuit on Page 1. The typical FB reference is internally regulated to 95mV. The LED current is 95mV/RS. It's recommended to use a 1% or better precision resistor for the better LED current accuracy. The formula and table 1 for RS selection are shown as follows: RS  95mV / ILED Table 1. RS Resistor Value Selection Standard Value (Ω) ILED(mA) 0.18 0.15 0.12 0.10 528 633 792 950 PCB Layout Guidelines As for all switching power supplies, the layout and components placement of the PAM2803 is an important step in the design; especially at high peak currents and high switching frequencies. The input capacitor and output capacitor should be placed respectively as close as possible to the input pin and output pin of the IC; the inductor and schottky diode should be placed as close as possible to the switch pin by using wide and short traces for the main current path; the current sense resistor should be placed as close as possible between the ground pin and feedback pin. PAM2803 Document number: DS36400 Rev. 2 - 2 6 of 9 www.diodes.com December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 Ordering Information PAM2803 X X X X Pin Configuration A Type: 1. SW 2. GND 3. FB 4. SHDN 5. VOUT 6. VIN Part Number PAM2803AAF095 Package Type Number of Pins A: SOT23-6 F: 6 Marking Refer to Marking Information Below FB Voltage 095: 95mV Package Type Standard Package SOT23-6 3,000 Units/Tape&Reel Marking Information PAM2803 Document number: DS36400 Rev. 2 - 2 7 of 9 www.diodes.com December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 Package Outline Dimensions (All dimensions in mm.) SOT23-6 PAM2803 Document number: DS36400 Rev. 2 - 2 8 of 9 www.diodes.com December 2014 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2803 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). 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