CMD W High Power White LED Driver. General Description. Features. Applications. Typical Application. Block Diagram

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1 Features LED Power Efficiency: up to 90% Current ccuracy:±5%( IN=3.6 F=3.7) Low Start-Up oltage: 0.9(ILED=70m) Low Hold oltage:0.75(iled=00m) MHz Switching Frequency Uses small, Low Profile External Components Low RDS(ON) : 00mΩ (TYP.) Open LED Protection Over Temperature Protection Low Profile Package Pb-Free Package pplications White LED Torch (Flashlight) White LED Camera Flash DSC(Digital Still Camera)Flash Cellular Camera Phone Flash PD Camera Flash Camcorder Torch(Flashlight) Lamp General Description The CMD803 is a set-up DC-DC converter that delivers a regulated output current. The device switches at a.0mhz constant frequency, allowing for the use small value external inductor and ceramic capacitors. of The CMD803 is targeted to be used for driving loads up to from a two-cell alkaline battery. The LED current can be programmed by the external current sense resistor, Rs, connected between thefeedback pin (FB) and ground. low 95m feedback voltage reduces the power loss in the Rs for better efficiency. With its internal, 00mΩ 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 u. The CMD803 is available in the 6-lead package. Typical pplication Block Diagram IN C IN 0uF OFF ON 4.uH SW 6 IN OUT CMD803 SHDN GND FB I LED =750m, R S =0.7Ω 5 3W WLED 3 C O 0uF R S 95m Reference SHDN FB + - Shutdown nd Soft-start Rc Cc Σ Ramp Generator.0MHz Oscillator Comparator - + OUT IN SW PWM Logic nd Driver + - GND

2 Pin Configuration& Marking Information Top iew XX: Product Code : oltage Code Y: Year W: Weekly XX Y W 3 Pin Number Name SW GND FB SHDN OUT IN Function Switch Ground Feedback Shut Down Output Input bsolute 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. ll voltages are with respect to ground. Input Pin oltage to 6 SW Pin oltage to 6 SHDN, FB Pin oltage to 6 Recommended Operating Conditions Junction Temperature C to 5 C Operating Temperature Range C to 85 C Storage Temperature Range C to 5 C Lead Temperature (Soldering, 5 sec) C mbient Temperature C to 85 C Thermal Information Parameter Package Symbol Maximum Unit Thermal Resistance (Junction to Case) Thermal Resistance (Junction to mbient) θjc θj /W Internal Power Dissipation PD 400 mw

3 Electrical Characteristic T =5, IN =.4, I LED =750m, SHDN =, L=.uH, C =0uF, C =0uF, unless otherwise noted. IN ΙΝ O Parameter Symbol Conditions Min Typ Max Unit Input oltage Range IN 0.9 F-0. (note ) Feedback oltage FB m Start-up oltage STRT : 0 3 IN I LED =70m 0.9 Hold oltage HOLD : 3 0 IN I :750m 00m LED 0.75 Oscillator Frequency SHDN Input High SHDN Input Low Over Temperature Shutdown Over Temperature Hysteresis Maximum Output Current Range FOSC SH SL OTS OTH I O(MX) IN =.8 IN = MHz m Quiescent Current I Q I LED =0m, O =3.4, Device Switching at MHz 3 m Shutdown Current Switch on Resistance Current Limit Efficiency ISD RDSON ILIM η Shutdown mode O =3.4 O =3.4 ILED=750m u Ω % Note: - LED Forward oltage F 3

4 i t i CMD803 Typical Performance Characteristics T =5, L=.uH, C =0uF, C =0uF, unless otherwise noted. ΙΝ Ο 00. LED Power Efficiency vs Input oltage. LED Current vs Input oltage y ( %) enc c 80 (m ) 700 ILED =750m@F=3.7 P ower E f f LED I F =750m@ =3.7 E D C u rre n LE D 50 L Input oltage() Input oltage().5. DC I nput Cur r ent ( m ) DC Input Current vs Input oltage ILED=750m@F=3.7 F eedbac k olt age( m ) Feedback oltage vs Input oltage (ILED =750m@ F =3.7) Input oltage() Input oltage() 4

5 Typical Performance Characteristics (continued) 5. Switching Waveform 6. Start-Up Waveform SHDN SW O C Coupling O I L I L 7. Overvoltage Protection 5

6 pplication Information Inductor Selection The CMD803 can use small value inductors due to its switching frequency of MHz. The value of inductor will focus in the range of.uh to 4.7uH for most CMD803 applications. In typical high c u r r e n t w h i t e L E D a p p l i c a t i o n s, i t i s recommended to use a 4.7uH inductor. The inductor should have low DCR (DC resistance) to minimize the I R power loss, and it requires a current rating of to handle the peak inductor current without saturating. Capacitor Selection n input capacitor is required to reduce the input ripple and noise for proper operation of the CMD803. For good input decoupling, Low ESR (equivalent series resistance) capacitors should be used at the input. t least.uf input capacitor is recommended for most applications. minimum output capacitor value of 6.8uF is r e c o m m e n d e d u n d e r n o r m a l o p e r a t i n g conditions, while a 0uF-uF capacitor may be required for higher power LED current. reasonable value of the output capacitor 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 CMD803 applications. The X5R and X7R types are preferred because they maintain capacitance over wide voltage and temperature ranges. 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. The typical FB reference is internally regulated to 95m. The LED current is 95m/Rs. It's recommended to use a % or better precision resistor for the better LED current accuracy. The formula and table for Rs selection are shown as follows: Rs=95m/ILED Table. Rs Resistor alue Selection Standard alue(ω) PCB Layout Guidelines ILED(m) s for all switching power supplies, the layout and components placement of the CMD803 is an important step in the design; especially at h i g h p e a k c u r r e n t s a n d h i g h s w i t c h i n g 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. Diode Selection It's indispensable to use a Schottky diode rated at with the CMD803. 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. I n a p p l i c a t i o n, t h e O N S e m i c o n d u c t o r MBR0LT3G is recommended. 6

7 Ordering Information CMD803 X X X X FB oltage Number of Pins Package Type Pin Configuration Pin Configuration Type. SW Package Type : Number of Pins F: 6 FB oltage 095:95m. GND 3. FB 4. SHDN 5. OUT 6. IN Part Number Marking Package Type Standard Package CMD803F095 CFYW 3,000Units/Tape&Reel Please consult PM sales office or authorized Rep./Distributor for detailed ordering information. 7

8 Outline Dimension e e SEE IEWS b WITH PLNTING c BSE METL SECTION E E L L IEW B θ GUGE PLNE SETING PLNE Symbol b c D E Spec.0± ±0.05.0± ±0. 0.5± ±0..80±0. Symbol E e e L L θ Spec.60± BSC.90BSC 0.55± REF 4 ±4 8