LED7708TR STMicroelectronics

LED7708 16 channels x 85 mA LED driver with boost controller and 4-wire serial interface Datasheet production data Features Boost controller section 3.6 V to 36 V input voltage range (LDO) Adaptive output voltage for high efficiency 6&1&0. X X , Internal +5 V LDO for gate driver supply PITCH Internal +3.3 V LDO for device supply High performance external MOSFET driver Description 250 kHz to 1 MHz switching frequency Programmable OV and OC protection The LED7708 has been specifically designed to Fixed frequency peak current-mode control supply several LEDs starting from a single low- voltage rail. It integrates a boost controller, External synchronization for multi-device sixteen current generators and a 4-wire serial application interface. The boost controller regulates the Overtemperature alert and thermal output voltage in an adaptive way, according to shutdown the LED requirements, resulting in an improved LED array driver section overall efficiency. All the current generators are 16 channels with 85 mA/ch current 40 V-rated, allowing the LED7708 to drive several capability LEDs in series on each channel. The channels 2% channel current accuracy can be put in parallel for higher output current. 2% channel-to-channel current matching The brightness of the LEDs is controlled by using LED short-circuit and open channel fault the serial interface. A selectable 12-bit or 16-bit detection and management grayscale brightness control allows independent 4-wire, 30 MHz serial interface PWM on each channel. A programmable on-chip dimming oscillator is provided for external circuitry 16 x16-bit, 1x256-bit or 1x192-bit serial simplification. The device has dedicated pins to data formats lock to an external synchronization with other Grouped or independent channel PWM devices (master or slave) for noise reduction in control multi-device applications. The LED7708 Selectable 12/16-bit grayscale brightness implements basic protection (OVP, OCP and control for local dimming thermal shutdown) as well as LED array Programmable internal dimming oscillator protection. It can detect and manage open-LED Programmable grayscale latency and shorted-LED faults and different fault- Master/slave chain configuration supported management options are available in order to cover most application needs. Applications Table 1. Device summary TV and monitor backlight units for LCD panels Order codes Package Packing Medium and large size LCD panel backlights LED7708 Tube VFQFPN-48 7x7 RGB/RGGB backlight solutions Tape and (exposed pad) LED7708TR reel May 2012 Doc ID 022698 Rev 1 1/53 This is information on a product in full production. www.st.com 53Contents LED7708 Contents 1 Typical application circuit 6 2 Pin function 7 3 Absolute maximum ratings 10 4 Recommended operating conditions 12 5 Electrical characteristics 13 6 Block diagram . 17 7 Device description . 18 7.1 Device supply 18 8 Recommended operating conditions 19 8.1 Device power-up and soft-start 20 8.2 Device shutdown . 21 8.3 Boost controller section and output voltage control . 21 8.3.1 Output voltage optimization 21 8.3.2 Boost converter loop . 24 8.3.3 Slope compensation . 25 8.3.4 External MOSFET control . 26 8.4 Current generators section 27 8.5 Serial interface . 29 8.5.1 Serial interface architecture 29 8.5.2 Serial interface internal registers 29 8.5.3 Internal registers access 30 8.5.4 Brightness data formats . 31 8.5.5 Brightness registers (BRTxx) . 33 8.5.6 DEVCFG0 register . 33 8.5.7 DEVCFG1 register . 35 8.5.8 GSLAT register . 36 8.5.9 CHSEL register . 37 2/53 Doc ID 022698 Rev 1