STEVAL-ILL031V1 Digital constant-current controller for LED driving based on the STM8S208x Data brief Features ■ DC input voltage: 48 V ■ Buck stage adapts output voltage to drive LEDs with selected current ■ Four DC-DC buck converters allow driving of 4 LED strings, managing up to 120 W ■ Employs 3 W LEDs to obtain 30 W-per-string (10 LEDs in series in each string) ■ Low voltage-sensing circuitry ■ Logic level MOSFETs driven by the microcontroller without gate driver (ground referred) ■ High efficiency (up to 98%) ■ RoHS compliant STEVAL-ILL031V1 Description The purpose of the STEVAL-ILL031V1 demonstration board is to present a new digital approach to performing real average current control on an LED streetlighting platform. This LED streetlight platform is developed on a DC-DC “inverse buck” converter, taking advantage of power switch control and conditioning signal circuitry for current sensing. Benefits of this design include low energy consumption, low maintenance, and reduced size and weight. The solution is customized for streetlighting applications, but can be extended to many other segments. November 2010 Doc ID 17237 Rev 2 For further information contact your local STMicroelectronics sales office. 1/6 www.st.com 6 2/6 3 4 2 1 +5V C18 Comm Connect or 100nF J9 1 3 CON4A J10 Doc ID 17237 Rev 2 1M R14 R15 68R C15 180pF RESET# OSC I N OSC OUT TIM2_CH3 SPI_MOSI_LCD R23 4 3 0 J11 2 1 PWM1-FirstString PWM2-SecondString PWM3-ThirdString PWM4-FourthString RESET# +5V JOY_SEL BEAD L5 C20 10uF +5V_VDDA C21 10nF VDDA PD7_JOY STICK_SEL PD1_Swim PC6_MOSI PWM1-PC1 PWM2-PC2 PWM3-PC3 PWM4-PC4 8 40 7 19 5 20 4 39 57 58 59 60 61 62 63 64 34 35 36 37 38 41 42 1 2 3 9 TIM2_CH3 PA4 UART_RX 10 PA5 UART_TX 11 12 470nF C17 6 30 4k7 R18 +5V Enable_1 R16 29 Enable_2 28 0 R17 0 27 PB4_JOYSTICK_LEFT 26 JOY_LEFT PB5_JOYSTICK_RIGHT 25 JOY_RIGHT PB6_JOYSTICK_UP 24 JOY_UP PB7_JOYSTICK_DOWN 23 JOY_DOWN X1 +5V PD2/TIM3_CH1/[TIM2_CH3] Swim Connector 2 4 C16 20pF 24MHz C14 20pF 100nF VDDIO_1 VDDIO_2 VDD VDDA VSS VSSA VSSIO_1 VSSIO_2 STM8S208RB PD3/TIM2_CH2/[ADC_ETR] PD4/TIM2_CH1/[BEEP] PD5/UART3_TX PD6/UART3_RX PD7/TLI/ [TIM1_CH4] PD0/TIM3_CH2/[TIM1_BKIN]/[ CLK_CCO] PD1/SWIM PC1/TIM1_CH1 PC2/TIM1_CH2 PC3/TIM1_CH3 PC4/TIM1_CH4 PC5/SPI_SCK PC6/SPI_MOSI PC7/SPI_MISO NRST PA1/OSCIN PA2/OSCOUT PA3/TIM2_CH3/[TIM3_CH1] PA4/UART1_RX PA5/UART1_TX PA6/UART1_CK VCAP PB0/AIN0/[ TIM1_CH1N] PB1/AIN1/[ TIM1_CH2N] PB2/AIN2/[ TIM1_CH3N] PB3/AIN3/[ TIM1_ETR] PB4/AIN4/[I 2C_SCL] PB5/AIN5/[I 2C_SDA] PB6/AIN6 PB7/AIN7 U1 SW1 reset Vref - Vref + PI0 PG0/CAN_TX PG1/CAN_RX PG2 PG3 PG4 PG5 PG6 PG7 PF0/AIN10 PF3/AIN11 PF4/AIN12 PF5/AIN13 PF6/AIN14 PF7/AIN15 PE0/CLK_CCO PE1(T)/I2C_SCL PE2(T)/I 2C_SDA PE3/TIM1_BKIN PE4 PE5/SPI_NSS PE6/AIN9 PE7/AIN8 21 18 48 R30 0R Vref + R29 0R +5V D5 D6 D7 D8 LCD_CS PG1 PG2 PG3 C19 1uF R19 0R R24 1k R25 1k R27 1k R26 1k Sensing-ThirdString Sensing-FourthString Dimming Sensing-SecondString Sensing-First String +5V_VDDA First String SecondString ThirdString FourthString PG0_LCD_CS 43 44 45 46 47 49 50 51 Enable Enable Enable Enable PF0-Ch10-ThirdString PF3-Ch11-FourthString PF4-Ch12-Dimming 4k7 R20 4k7 R21 4k7 R22 22 17 16 15 14 13 56 55 54 53 52 33 32 PE6-Ch9-SecondString PE7-Ch8-First String 31 R81 3k 2 1 3 +5V GND P1 10k Figure 1. 10K R13 1 C13 +5V Schematic diagrams STEVAL-ILL031V1 Schematic diagrams Control stage schematic (1 of 2) !-V STEVAL-ILL031V1 Schematic diagrams Figure 2. Control stage schematic (2 of 2) 6 6 # P& # # P& P& # '.$ N& # # N& N& 6 2 2 2 2 2 2 2 2 2 2 + + + + + 2 2 2 2 2 2 '.$ */9?,%&4 */9?2)'(4 */9?50 */9?$/7. */9?3%, * */934)#+-4! # # # # # N& N& N& N& N& '.$ '.$ '.$ '.$ '.$ *OYSTICK * 07-&IRST3TRING 07-3ECOND3TRING 07-4HIRD3TRING 07-&OURTH3TRING 3ENSING&IRST3TRING # P& * 07-#/..%#4/2 -!,% '.$ 2 '.$ K 6 $ # P& # P& 2%$ 3%.3).' #/..%#4/2 -!,% '.$ '.$ # P& 3ENSING 3ECOND3TRING 3ENSING 4HIRD3TRING 3ENSING &OURTH3TRING '.$ '.$ 0LACEONBOTTOMSIDE 0LACEONBOTTOMSIDE !-V Doc ID 17237 Rev 2 3/6 Schematic diagrams STEVAL-ILL031V1 Figure 3. Power stage schematic 6BUS $ * 3403,!3-! # N&6 , * #/. # U6 6 1 34..&3/4 2 #/. ½ 07-&IRST3TRING 2 ½ 2 27 # P 6BUS 6BUS * $ 3403,!3-! # N&6 #/. , # U6 1 34..&3/4 2 07-3ECOND3TRING ½ 2 3ENSING3ECOND3TRING ½ '.$ 2 27 6 # P $ * 6BUS .$/ 6BUS #/. # # U&6 $ * 3403,!3-! N&6 # N&6 , # U6 '.$ #/. 1 34..&3/4 2 07-4HIRD3TRING ½ 2 3ENSING4HIRD3TRING ½ 2 27 # P 6BUS 6BUS * $ 3403,!3-! # N&6 , #/. # U6 1 34..&3/4 2 07-&OURTH3TRING ½ 2 3ENSING&OURTH3TRING ½ 2 27 # P 6BUS !-V 4/6 Doc ID 17237 Rev 2 STEVAL-ILL031V1 2 Revision history Revision history Table 1. Document revision history Date Revision 23-Apr-2010 1 Initial release. 2 – Changed board photo on coverpage – Divided control stage schematic diagram into two figures (Figure 1 and Figure 2) to improve readability – Added Figure 3: Power stage schematic 11-Nov-2010 Changes Doc ID 17237 Rev 2 5/6 STEVAL-ILL031V1 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. 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