PAM2808 5W High Power HBLED Driver Features n n n n n n n n n General Description The PAM2808 is a 5W high power HBLED driver with 1.5A constant current. It features high efficiency and low quiescent current,making it ideal for battery powered applications. High Output Current Up to 1.5A Low Feedback Voltage:0.1V Stable with a Ceramic Output Capacitor Low Quiescent Current Open Load LED Protection Over Temperature Shutdown Low Temperature Coefficient Standard SOP-8(EP) Packages Pb-Free Package The PAM2808 features over current protection and over temperature shutdown. The PAM2808 is stable with a ceramic output capacitor of 4.7 μF or higher. PAM2808 is available in SOP-8(EP) package. Applications n High Bright LED Driver n White LED Torch (Flashlight) Typical Application Circuit VIN VIN EN C IN 4.7 μF VOUT VOUT PAM2808 GND FB CO 4.7 μF Rs Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 1 PAM2808 5W High Power HBLED Driver Block Diagram VIN VOUT OverCurrent Shutdown Thermal Shutdown EN AMP Reference FB GND Pin Configuration & Marking Information Top View SOP-8(EP) NC 1 VIN 2 8 NC 7 VOUT EN 3 6 FB 4 5 NC GND V: Voltage Code X : Internal Code Y: Year W : Week Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 2 PAM2808 5W High Power HBLED Driver Absolute Maximum Ratings 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. Input Voltage...............................................6.5V EN, FB, VOUT Pin Voltage .................................................-0.3V to V IN +0.3V Maximum Output Current......................P D /(V IN -V O ) Storage Temperature ....................- 65°C to 150°C Maximum Junction Temperature.................. 150 °C Lead Soldering Temperature (5sec)........... 300 °C Recommended Operating Conditions Maximum Supply Voltage..............................6V Junction Temperature Range........-40 °C to 125 °C Ambient Temperature Range...........-40 °C to 85°C Thermal Information Parameter Thermal Res istance (Junction to Case) Thermal Res istance (Junction to Ambient) Symbol Package Maxim um Unit θJC SOP-8(EP) 11 °C/W θJA SOP-8(EP) 90 °C/W Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 3 PAM2808 5W High Power HBLED Driver Electrical Characteristic V IN =4.5V,T A =25°C, C IN =4.7μF, C O =4.7 μF, unless otherwise noted. PARAMETER Input Voltage FB Reference Voltage Output Current Over Temperature Shutdown Over Temperature Hysteresis SYMBOL Test Conditions VI N MIN 2.5 V REF IO TYP MAX UNITS 6.0 V 0.1 Rs =0.3Ω 330 Rs =0.14Ω 700 Rs =0.1Ω 1000 Rs =0.067Ω 1500 V mA OTS 150 O C OTH 40 O C EN Input High Threshold VEH V IN =2.5V to 5V EN Input Low Threshold V EL V IN =2.5V to 5V Shutdown Current IS D V E N=0V 1.5 V 0.3 V 1 µA Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 4 PAM2808 5W High Power HBLED Driver Typical Performance Characteristics TA =25°C,CIN =4.7 μF,Co=4.7 μF,unless otherwise noted. 1. LED Current vs Input Voltage 2. Feedback Voltage vs Input Voltage 1400 120 1200 100 1000 80 800 60 600 40 400 200 0 3.0 1W 3W 3.5 4.0 4.5 5.0 20 2W 5W 5.5 1W 3W 2W 5W 0 3.0 6.0 3.5 4.0 4. 5 5.0 5.5 6.0 Input Voltage(V) Input Voltage(V) 3. Dropout Voltage vs LED Current 4. Start up 350 300 250 200 150 100 50 0 0 500 1000 1500 2000 LED Current (mA) Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 5 PAM2808 5W High Power HBLED Driver Application Information External Capacitor Requirements In ge ne r al , t he m a x im um ex p ec t ed po we r (P D (max)) consumed by a linear regulator is computed as: A 4.7µF or larger ceramic input bypass capacitor, connected between V IN and GND and located close to the PAM2808, is required for stability. A 4.7 μF minimum value capacitor from V O to GND is also required. To improve transient response, noise rejection, and ripple rejection, an additional 1 0 µF o r l a r g e r , l o w E S R c a p a c i t o r i s recommended at the output. A higher-value, low ESR output capacitor may be necessary if large, fast-rise-time load transients are anticipated and the device is located several i nches from the power source, especially if the minimum input voltage of 2.5 V is used. PDMAX= (V I (avg)-VO (avg ))×I O (avg)+VI (avg )×I (Q ) Where: l V I (avg) is the average input voltage. l V O(avg) is the average output voltage. l I O(avg) is the average output current. l I (Q) is the quiescent current. The quiescent current is insignificant compared to the average output current; therefore, the term V I(avg) xI (Q) can be neglected. The operating junction temperature is computed by adding the ambient temperature (TA ) and the increase in temperature due to the regulator' s power dissipation. The temperature rise is computed by multiplying the maximum expected power dissipation by the sum of the thermal resistances between the junction and the case ( R θJC ), the case to heatsink (R θCS ), and the heatsink to ambient (R θSA). Thermal resistances are measures of how effectively an object dissipates heat. Typically, the larger the device, the more surface area available for power dissipation so that the object’s thermal resistance will be lower. Regulator Protection The PAM2808 features internal current limiting, thermal protection and short circuit protection. During normal operation, the PAM2808 limits output current to about 2.5A. When current limiting engages, the output voltage scales back linearly until the over current condition ends. While current limiting is designed to prevent gross device failure, care should be taken not to exceed the power dissipation ratings of the package. If the temperature of the device exceeds 150°C, thermal-protection circuitry will shut down. Once the device has cooled down to approximately 40°C below the high temp trip point, regulator operation resumes. Thermal Information The amount of heat generates is: P D =(V IN -V O )IO . All integrated circuits have a maximum allowable junction temperature (T J max) above which normal operation is not assured. A system designer must design the operating environment so that the operating junction temperature (T J) does not exceed the maximum junction temperature (TJ max). The two main environmental variables that a designer can use to improve thermal performance are air flow and external heatsinks. The purpose of this information is to aid the designer in determining the proper operating environment for a linear regulator that is operating at a specific power level. Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 6 PAM2808 5W High Power HBLED Driver Ordering Information PAM2808X X X xxx X Shipping Package Output Voltage Number of Pins Package Type Pin Configuration Pin Configuration B Type: Package Type Num ber of Pins Shipping Package B: 8 R: Tape & Reel L: SOP-8(EP) 1. NC 2. VIN 3. EN 4. GND 5. NC 6. FB 7. VOUT 8. NC Part Number Marking Package Type MOQ & Shipping Pckage PAM2808BLBR P2808 XXXYW SOP-8(EP) 2,500 Units /Tapes &Reel Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 7 PAM2808 5W High Power HBLED Driver Outline Dimensions SOP-8(EP) Power Analog Microelectronics, Inc www.poweranalog.com 08/2011 Rev1.0 8