3 2 L E D D R I V E R S : ICs LED7707 Monolithic DC/DC Converter for LED Driving The new LED7707 is a monolithic DC/DC converter for LED driving specifically designed for LCD backlighting and general lighting. It consists of a highly-efficient boost converter integrating a power MOSFET and six controlled-current generators (ROWs). The device can manage an output voltage up to 36V (example is 10 white LEDs x row). The boost section is based on a constant switching frequency, peak current-mode architecture. The boost output voltage is controlled so that the lowest voltage of the ROW, referred to SGND, is equal to an internal reference voltage (700 mV typical). The input voltage range is from 4.5V up to 36V. In addition, the LED7707 has an internal 5V LDO regulator that supplies the internal circuitry of the device and is capable of delivering up to 40 mA. The input of the LDO is the main input voltage (V ). The boost section switching frequency can be externally BATT adjusted from 200 kHz to 1 MHz. It also has an internal fixed value of 660 kHz (typical), which eliminates the need for a resistor, an important feature in minimum component-count applications. The frequency pin (FSW) can also be used as the synchronization input, allowing the LED7707 to operate both as the master or the slave. The generators can be externally programmed to sink from 16 mA up to 85 mA and can be dimmed via a PWM signal (1 percent dimming duty-cycle at 1 kHz can be managed). For high- LED7707 demo board current LEDs, it is possible to parallel the outputs to get the maximum output current value of 510 mA (6 ROWs x 85 mA). The device is able to detect and manage open- and shorted-LED faults. If some ROWs are not used, during the start up, the device is able to self-detect and automatically disconnect the ROWs without any fault detection. Output over-voltage, internal power MOSFET over-current, and thermal shutdown are provided as protection. Features Benefits Applications Constant-frequency, peak, current control mode High efficiency thanks to Backlighting in LCD panels adaptive-output voltage for battery/AC adapter Internal power MOSFET supplied equipment such as: High-performance 36V External sync for multi-device applications rated current generators - GPS navigator backlighting Pulse-skip power saving mode at light load 1% dimming duty-cycle at - LCD monitor backlighting Programmable soft-start and over 1 KHz can be managed General lighting voltage protection Keeps externals tiny Ceramic output capacitor Demo board and Six ROWs with 85 mA maximum current application notes available capability (adjustable) Parallelable rows up to 510 mA (6 ROWs x 85 mA) Up to 36V output voltage (example 10 white LED per row) 2% current matching between ROWs LED failure (open- and short-circuit) detection Housed in VQFPN-24L space-saving package Product Specifications Number Input Output Output Peak Dimming Number Diagnostic Part Number Type of LEDs/ Configuration Voltage Voltage Current Efficiency Interface Markets Type of Strings Capabilities String (VDC) (VDC) (mA) (%) LED7707 Boost converter PWM 36V (example 10 white LEDs) 6 Series/parallel 4.5-36 Adaptive to 36V 6 ROWs x 85 >90 Short/open COMMERCIAL LIGHTING FLASHLIGHTS TRANSPORTATION BACKLIGHTING SIGNAGE MMAARRKKEETTSS LLEEGGEENNDD LED7707 application schematic Arrow Electronics Lighting Group 1.888.9LIGHT1 L E D D R I V E R S : ICs 3 3 24-Bit Constant-Current LED Sink Driver with Output Error Detection The STP24DP05 is a monolithic, low-voltage, low current-power 24-bit shift register designed for LED panel displays. The 24-bit are grouped into three sets of 8-bit for RGB control to simplify PCB layout in parallel to achieve high resolution video display. In the output stage, 24 regulated current sources were designed to provide 5 mA to 80 mA constant current to drive the LEDs. The 8 x 3 shift registers data flow sequence order can be managed with two dedicated pins. The STP24DP05 has a dedicated pin to activate the outputs with a sequential delay that will prevent in-rush current during outputs turn-on. The device detection circuit checks three different conditions that can occur on the output line: short-to-GND, short-to-VO, or open line. The data detection results are loaded in the shift registers and shifted out via the serial line output. The detection functionality is activated with a STP24DP05 evaluation board dedicated pin, or as an alternative, through a logic sequence that allows the user to enter or exit from detection mode. Through three external resistors, users can adjust the output current for each 8-channel group, controlling the light intensity of LEDs. Features Benefits Applications 20V output driving capability Superior display quality Full-motion RGB video wall display 25 MHz clock frequency Finer brightness control Monochrome LED signs through three independent 3.3V and 5V supply voltage range Billboards and scoreboards external resistors Up to 80 mA drive capability Large-panel LCD backlighting units Accurate color balance per channel Traffic display and white points Thermal shutdown Gaming machine Remote diagnostics Thermal error flag Channel letter signs Gradual outputs delay Short- and open-LED detection Controlled in-rush current TQFP-48 exposed pad, high thermal efficiency package Product Specifications Number Input Output Output Peak Number of Part Number Type Dimming Type of LEDs/ Configuration Voltage Voltage Current Efficiency Diagnostic Capabilities Interface Markets Strings String (VDC) (VDC) (mA) (%) STP24DP05 Linear SW/PWM signaling 20V (example 6 green LEDs) 24 Series/parallel 3.3-5 20 80 Open/short LED detection SPI MMAARRKKEETTSS LLEEGGEENNDD COMMERCIAL LIGHTING FLASHLIGHTS TRANSPORTATION BACKLIGHTING SIGNAGE STP24DP05 typical application circuit Arrow Electronics Lighting Group 1.888.9LIGHT1