ALED7707

ALED7707 Automotive 6-row 85 mA LEDs driver with boost regulator for LCD panels backlight Datasheet - production data Applications • Infotainment LCD backlight • Daytime running lights • Car interior/exterior lights • Dashboard backlight Description QFN 5x5 - 24L Features • AEC-Q100 qualification • Boost section – 4.5 V to 36 V input voltage range – Internal power MOSFET – Internal +5 V LDO for device supply – Up to 36 V output voltage – Constant frequency peak current-mode control – 250 kHz to 1 MHz adjustable switching frequency – External synchronization for multi-device application – Pulse skip power saving mode at light load – Programmable soft-start – Programmable OVP protection – Stable with ceramic output capacitors – Thermal shutdown The ALED7707 device consists of an automotive grade (AEC Q100 compliant) monolithic boost converter and six controlled current generators (rows) specifically designed to supply LED arrays used in the backlighting of LCD panels. The device can manage an output voltage up to 36 V (i.e.: 10 white LEDs per row). The generators can be externally programmed to sink up to 85 mA and can be dimmed via a PWM signal (1% dimming duty cycle at 1 kHz can be managed). The device allows the open and shorted LED faults to be detected and managed and unused rows to be let floating. Basic protections (output overvoltage, internal MOSFET overcurrent and thermal shutdown) are provided. Table 1. Device summary Order code Package ALED7707 Packing Tube QFN 5x5 - 24L ALED7707T Tape and reel • Backlight driver section – Six rows with 85 mA maximum current capability (adjustable) – Rows disable option – Less than 10 µs minimum dimming on-time – ± 3% current matching between rows – LED failure (open and short-circuit) detection October 2018 This is information on a product in full production. DocID027854 Rev 3 1/36 www.st.com Contents ALED7707 Contents 1 Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 2.1 Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5 Operation description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.1 5.2 5.3 2/36 Boost section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 5.1.1 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.1.2 Enable function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.1.3 Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.1.4 Overvoltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.1.5 Switching frequency selection and synchronization . . . . . . . . . . . . . . . 15 5.1.6 Slope compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5.1.7 Boost current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.1.8 Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Backlight driver section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2.1 Current generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2.2 PWM dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Fault management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 5.3.1 FAULT pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 5.3.2 MODE pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 5.3.3 Open LED fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 5.3.4 Shorted LED fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 DocID027854 Rev 3 ALED7707 6 Contents Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1 System stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1.1 6.2 Loop compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7 Electrical characteristics (curves) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 8.1 9 QFN 5x5 - 24L package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 DocID027854 Rev 3 3/36 36 Typical application circuit 1 ALED7707 Typical application circuit Figure 1. Application circuit 9,1 6ORSH FRPSHQVDWLRQ 2XWSXW 293VHOHFWLRQ 0/&& 6ZLWFKLQJ IUHTXHQF\ VHWWLQJ )6: 296(/ /'2 6/23( /; 9,1 $9 && 9 52:  ,QWHUQDO 0262&3 %,/,0 52:  5,/,0 52:  5RZV FXUUHQWVHWWLQJ $/(' 66 52:  3*1' 02'( 6 VUVLO,ON 25 LDO maximum output current mV mA VLDO5 < VUVLO,OFF 11 20 36 130 200 660 750 Boost section tON,min Minimum switching on-time fSW Default switching frequency FSW connected to AVCC 550 Minimum FSW sync frequency FSW sync frequency range SYNC output duty cycle SYNC output high level SYNC output low level 8/36 (1) ns 220 FSW sync signal: 200 mV to 400 mV, 270 ns pulse duration FSW connected to AVCC (internal oscillator selected) ISYNC = 10 µA ISYNC = -10 µA DocID027854 Rev 3 kHz 200 28 1000 34 40 VAVCC -20 % mV 20 ALED7707 Electrical characteristics Table 5. Electrical characteristics (continued) Symbol Parameter Test conditions Min. Typ. Max. Unit Power switch KB RDS(on) LX current coefficient RBILIM = 600 kΩ 1 ⋅ 106 1.2 ⋅ 106 1.45 ⋅ 106 Internal MOSFET on-resistance 280 570 1.145 1.2 V mΩ OC and OV protections VTH,OVP Overvoltage protection reference threshold 1.1 V Soft-start and power management EN, turn-on threshold 1.6 EN, turn-off threshold 0.8 DIM, high level threshold V 1.3 DIM, low level threshold 0.8 EN, pull-up current 1.5 2.5 3.8 SS, charge current 3.5 5 6 SS, end-of-startup threshold 2.0 2.4 2.7 SS, reduced switching frequency release threshold 0.6 0.8 1.0 1776 1850 1924 V 3 4 % 700 830 mV 3.8 4.2 V 250 400 mV µA V Current generators section KR Current generators gain ∆KR(2) Current generators gain accuracy VIFB Vrowx, FAULT Feedback regulation voltage LED short-circuit detection threshold VFAULT, LOW FAULT pin low level voltage MODE tied to SGND IFAULT,SINK = 4 mA 3.5 Thermal shutdown TSHDN Thermal shutdown turn-off temperature 150 Thermal shutdown hysteresis 30 °C 1. Tested at TA = 25 °C. 2. IROW = KR / RRILIM, ΔIROW / IROW ≈ ΔKR / KR + ΔRRILIM / RRILIM. DocID027854 Rev 3 9/36 36 Operation description 5 ALED7707 Operation description The device can be divided into two sections: the boost section and the backlight driver section. These sections are described in the next paragraphs. Figure 3 provides an overview of the internal blocks of the device. Figure 3. Simplified block diagram 9,1 6/23( &XUUHQW VHQVH /'2 9 /'2 5DPS JHQHUDWRU    89/2 GHWHFWRU &203 B 89/2 /; =&' %RRVW FRQWURO ORJLF 9  JP B 3*1' %RRVWB(1 %,/,0 &XUUHQW OLPLW B 293 66 952: 3URWB(1 &75/ · &XUUHQW JHQHUDWRU  52: &XUUHQW JHQHUDWRU  52: &XUUHQW JHQHUDWRU  52: &XUUHQW JHQHUDWRU  52: &XUUHQW JHQHUDWRU  52: 952: &75/ ([WV\QF GHWHFWRU 952: 26& &75/ 952: &75/ )6: 952: 3URWB(1 89/2 (1 02'( &75/ %RRVWB(1 $9&& 296(/ 0LQYROWDJH VHOHFWRU 6RIWVWDUW 6