L99LD01 High efficiency constant current LED driver for automotive applications Datasheet - production data Regulated output for micro supply 5 V 2 % -20 mA Parameter programming and settings of internal memory registers by the dedicated SPI interface: LQFP32 7x7 mm GAPG1506151117CFT LED current reference adjusting ( 66.7 %) Maximum input current limiter reference adjusting ( 55.5 %) Features Random dither frequency sweeping, modulation frequency and deviation Max V 40 V BATT percentage Operation supply battery voltage Power on reset pin output 5.6 - 24 V V BATT ESD protection Oscillator frequency range 100 - 500 kHz Applications Automotive qualified Automotive day time running light, LED Constant current operation HeadLamps Current LED settable by external sensing resistor and adjustable via SPI Description Converter switching frequency adjustable by L99LD01 is a precise constant current DCDC external resistor (R ) SF converter LED driver for automotive applications, EMC reduction by internal spread spectrum dedicated to the control of high-brightness LED dither oscillator headlights and housed in a LQFP32 package. Low frequency PWM dimming operation. The device is designed to be used in Boost, Buck- Maximum input current limiter Boost and Fly back converter topologies. An internal random dither oscillator works in low Maximum switching duty cycle limiter frequency modulation, allowing the RF spectrum Slope compensation adjustable by external of the switching frequency to spread so to reduce resistor (R9) EMC emissions. The slope compensation Battery overvoltage shut down protection (ext. ensures good converter loop stability whatever is R3, R4 resistors required) the duty cycle needed by the application. Led chain OV detection (ext. R5, R6) The converter is able to work either in full power Multiplexed output for monitoring and control of mode or in low frequency dimming mode. LED temperature (external NTC resistor The device includes an internal low drop voltage required), voltage of LED chain, and low regulator, that can be used to supply a frequency PWM microcontroller, and a reset pin, that is useful for SPI communication serial interface transceiver resetting the microcontroller at the start up and (SDI, SDO, SCK, CSN) every time that the regulated output voltage falls down below an established voltage threshold. June 2015 DocID025319 Rev 3 1/69 This is information on a product in full production. www.st.comContents L99LD01 Contents 1 Block diagram and pin description . 6 2 Functional description . 8 2.1 Operating modes 8 2.1.1 Operation with an external microcontroller . 8 2.1.2 Stand alone operation . 9 2.1.3 Start-up fail 9 2.1.4 Normal mode . 10 2.1.5 Software limp home 10 2.1.6 Limp home mode 10 2.2 Protections and functions . 16 2.2.1 LED current adjust and temperature control . 16 2.2.2 Slope compensation . 17 2.2.3 LED chain overvoltage detection 18 2.2.4 Battery overvoltage shutdown 19 2.2.5 Regulators thermal shut down 19 2.2.6 Reset . 19 2.2.7 Watchdog 20 2.2.8 Standby and wake up by ENABLE pin 20 2.2.9 Frequency setting and dither effect 21 2.2.10 Start up LED overvoltage management . 23 2.2.11 Programming the over/under voltage threshold . 27 2.2.12 Input overvoltage programming . 29 3 SPI functional description . 31 3.1 Serial peripheral interface (ST SPI standard) 31 3.2 Signal description . 32 3.3 SPI protocol . 32 3.3.1 SDI, SDO format 32 3.3.2 Global status byte description 33 3.3.3 Operating code definition 34 3.4 Address mapping . 37 3.5 Control registers (RAM) 38 3.6 Status registers . 41 2/69 DocID025319 Rev 3