STEVAL-ILL010V1

STEVAL-ILL010V1 High intensity LED dimming driver evaluation board based on the L6902 Data Brief Features ■ Input voltage Vin= 8 V to 30 Vdc ■ Dimming interface ■ Analog current control ■ Average current control by PWM ) s ( ct u d o Description Thanks to their high efficiency and reliability, super high-brightness LEDs are becoming more and more popular as a subsitute for conventional light sources. Although LEDs can be supplied directly from a simple voltage source (like a battery with resistor), for most applications it is better to use a switching current source to achieve not only higher efficiency but also better light output. r P e t e l o )- This evaluation board is designed around an L6902D-based DC-DC converter with dimming interface. It board implements both of two well known dimming methods: s ( t c u d o ■ Analog current control ■ Average current control by PWM r P e s b O STEVAL-ILL010V1 The second dimming method implemented on this board is PWM control of average LED current. This control requires a digital PWM signal (with an amplitude of either 3.3 V or 5 V) between the dimming pin and the ground pin. Varying the dutycycle on the board will then change the brightness of the LED (100% = LED off, and 0% = LED fully on). t e l o While there is only a single dimming input connector on the board, it can be used for both dimming methods. s 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 For further information contact your local STMicroelectronics sales office. 1/4 www.st.com 4 8 - 24V + C1 10uF 25V CERAMIC R2 5k1 C3 22nF C4 220pF 4 8 COMP VCC GND 2 1 s b O t e l o 7 2/4 U1 P e L6902D OUT VREF J1 d o r 1 CS+ CS- 2 3 t c u 6 J3 3.3V Vref 5 ) (s FB D1 STPS34OU 100uH 1k R3 R1 9k1 R6 27k u d o 1 J4 ) s ( ct R5 8k2 Dimming Input C2 10uF 35V R4 1k + J6 GND Output J2 Rsense 0.33 1 2 Figure 1. 1 1 1 L1 Circuit schematic STEVAL-ILL010V1 Circuit schematic Schematic t e l o r P e s b O STEVAL-ILL010V1 2 Revision history Revision history Table 1. Document revision history Date Revision 11-Feb-2008 1 Changes Initial release. ) s ( ct u d o r P e t e l o ) (s s b O t c u d o r P e t e l o s b O 3/4 STEVAL-ILL010V1 Please Read Carefully: ) s ( ct Information in this document is provided solely in connection with ST products. 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