STEVAL-ILL010V1 High intensity LED dimming driver evaluation board based on the L6902 Data Brief Features ■ Input voltage V = 8 V to 30 Vdc in ■ Dimming interface ■ Analog current control ) s ■ Average current control by PWM ( t c u Description d o Thanks to their high efficiency and reliability, P r super high-brightness LEDs are becoming more e and more popular as a subsitute for conventional t light sources. Although LEDs can be supplied e l directly from a simple voltage source (like a o s battery with resistor), for most applications it is b better to use a switching current source to O STEVAL-ILL010V1 achieve not only higher efficiency but also better - light output. ) The second dimming method implemented on this s This evaluation board is designed arou(nd an board is PWM control of average LED current. L6902D-based DC-DC converter wictht dimming This control requires a digital PWM signal (with an interface. It board implements bouth of two well amplitude of either 3.3 V or 5 V) between the d known dimming methods: dimming pin and the ground pin. Varying the duty- o ■ Analog current contrrol cycle on the board will then change the brightness P of the LED (100% = LED off, and 0% = LED fully ■ Average curren t control by PWM e on). While there eist only a single dimming input connectolr on the board, it can be used for both o dimmsing methods. b O A signal between 0 and 3.3 V should be used for analog (peak current) dimming. When the dimming pin is grounded (0 V), the 350 mA maximum output current is provided. Likewise, when 3.3 V is applied to the pin, the current provided is zero and the LED is off. February 2008 Rev 1 1/4 For further information contact your local STMicroelectronics sales office. www.st.com 4

Circuit schematic STEVAL-ILL010V1 1 Circuit schematic Figure 1. Schematic utut NDND J2J2 12 OutpOutp RsenseRsense0.330.33 1 J6J6GG C2C210uF10uF35V35V 1k1k ++ R4R4 R5R58k28k2 putput ) R6R627k27k 1 cJ4J4tDimming InDimming In( s u R1R19k19k1 d o R3R3 1k1k P r e t HH e uu 100100 OUOU ol 44 S3S3 s L1L1 D1D1STPSTP b O - ) s ( 1 ct23 5 o d2D2D uOUT CS+CS-FERFBV 6 1 J3J33.3V Vref3.3V Vref 00 r 6969 P LL P e U1U1 VCC COMDNG 7 t e 8 4 l o FF b s C4C4220p220p O FF C3C322n22n R2R25k15k1 CC MIMI C1C110uF10uF25V25VCERACERA ++ 21 VV 44 22 J1J1 8 - 8 - 2/4

STEVAL-ILL010V1 Revision history 2 Revision history Table 1. Document revision history Date Revision Changes 11-Feb-2008 1 Initial release. ) s ( t c u d o r P e t e l o s b O - ) s ( t c u d o r P e t e l o s b O 3/4

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