WWW.Microsemi .COM LX27901 LX27901 LX27901 High Performance LED Controller TM PRODUCTION DATASHEET D E S C R IP T I ON KE Y FE A T UR ES The LX27901 is a high performance LED Direct PWM input dimming operation can Three Selectable Drive Modes to controller optimized for LCD-TV and other be realized by inputting a dimming pulse Support Wide Range of Topologies multi-lamp LCD display systems and train to DIM pin directly. Optimized Solution for Off PFC LED provides a cost competitive solution for off- The ACU BRITE algorithm allows the DC Drive Applications PFC LED drive applications. to DC converter to be turned off when the 0.8A Source & Sink Drive Capacity The controller provides a pair of PWM digital dimming operation is at off state to On Chip 5.25V Regulator drive signals with adequate capacity to drive eliminate no-load power losses. The Direct Connection to Input Voltage a half bridge or other double ended DC to controller also provides a proprietary up to 27V DC converter circuit with the addition of synchronous regulation function to allow the simple external circuitry to provide safety user to control the LED current and dimming ACU BRITE Algorithm to Provide Accurate Brightness Control at isolation. operation from an un-regulated switching Highest Operating Efficiency Over power supply source to minimize the number The device includes a regulated 5.25V Wide Dimming Duty Range of power conversion stages and the output (VDD) activated by the ENABLE associated losses and component costs. In User Selectable Dimming Mode input working from the VIN input voltage of synchronous regulation mode, AOUT and Control up to 27V. VDD is capable of providing BOUT form a pair of drive signals to control 5mA source current to external circuitry Synchronous Regulation Function the LED string pairs in AC current mode, while supplying the on chip driver stage and to Minimize Power Conversion and COUT provides another option to the control circuitry. Stage control the LED in DC current mode. The controller allows the user to utilize Accurate LED Current Matching In A versatile set of system monitoring and Combination With Microsemis Non- two different converter drive schemes, LLC protection functions are incorporated in the dissipative Balancing Technology resonant or PWM control mode, selected by LX27901 design to provide reliable the signal level at ENABLE pin, to best fit a Robust Operation at Open and protection of the device and the system. wide spectrum of application needs. Short LED Conditions Three input pins, ISNS, VSNS and In addition, a proprietary ACU BRITE Compensated External and Internal UVS/SYN are assigned to support the algorithm is incorporated in the dimming PWM Dimming Operation regulation and protection sense feedback control operation to allow the user to Dedicated Fault Indication needs over wide range of application adaptively adjust the PWM dimming duty to configurations. Likewise a dedicated fault LED Current and Voltage achieve accurate brightness control over a indication pin allows the user to generate a Monitoring wide dimming duty cycle range while direct fault report to the system and RoHS Compliant & Halogen Free maintaining the highest operating efficiency. configure addition protection features with The LX27901 supports analog LED current simple external circuits. A P P L IC A T I ONS control utilizing the BRTA pin as the analog The device is available in 16 lead SOIC LED current setting function. LCD LED Backlight TV surface mount package in the industrial temperature range. LCD LED Backlight Monitors Other LED Backlight Systems IMPORTANT: For the most current data, consult MICROSEMIs website: WWW.Microsemi .COM LX27901 LX27901 MSC LX27901ID xxxx LX27901 High Performance LED Controller TM PRODUCTION DATASHEET A A B S OL UTE M A X IMUM R AT I NGS P A C KA GE P I N OUT Supply Input Voltage, VIN ............................................................................... 0.3V to 36V VIN VDD Signal Outputs, VDD, AOUT, BOUT, C OUT ..............................................-0.3V to 6.5V Signal Inputs, C R, BRTA .................................................................. -0.3V to VDD+0.3V ENABLE AOUT Signal Inputs, ENABLE, DIM, ISNS, VSNS, UVS/SYN ................... -0.3V to VDD+0.3V GND C R Signal Outputs COMP, SST/BCOM, FAULT ............................................... -0.3V to VDD BRTA BOUT Maximum Junction Temperature ............................................................................... 150C Storage Temperature Range ......................................................................... -65 C to 150 C DIM C OUT Peak Package Solder Reflow Temperature (40 seconds maximum exposure) ........... 260C SST/ COMP Lead Temperature. (Soldering 10 seconds) ................................................................ 300C BCOM ISNS FAULT Notes: Exceeding these ratings could cause damage to the device. All voltages are with respect to UVS/ VSNS GND. Currents are positive into, negative out of specified terminal. These are stress ratings SYN only and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions are not implied. Exposure to LX27901ID Absolute Maximum Ratings for extended periods may affect device reliability. D PACKAGE (Top View) RoHS / Pb-free Matte Tin Pin Finish ELECTRICAL CHARACTERISTICS Unless otherwise listed, the following specifications apply over the operating ambient temperature of -40 C < Temp < 85 C, and VIN = 7.5V to 27V, except where otherwise noted and the following test conditions: VIN = 12V, C = 330pF, R = 15k C R C R Parameters Symbol Test Conditions/Comments MIN TYP MAX Units Power Controller Input Voltage VIN 7.5 27 V 1F bypass cap on VDD pin, Controller Operating Voltage VDD 5.0 5.25 5.5 V I = 0 to 5mA VDD Power Supply Input Current IIN AOUT, BOUT = no load, VDD = no load 7 10 mA Sleep Mode Current IDD VIN = 24V, V < 0.8V 200 400 A SLEEP ENABLE VDD Off Voltage ENABLE < 0.8V 0.1 V Enable ENABLE On EN 1.7 V H Shut Down EN 0.8 V L LLC resonant drive mode, VDD = LLC Resonant Mode V 2 2.8 V LLCTH Threshold 5.25V 0.25V PWM switching drive mode, VDD = PWM Switching Mode V 3.2 3.5 3.7 V PWMTH Threshold 5.25V 0.25V Synchronous LED Drive Mode Synchronous LED drive mode, VDD = V 4.3 VDD V SYN Threshold 5.25V 0.25V Input High Current EN ENABLE = 2V 10 A IIH Input Low Current EN 0V < V < 0.8V 5 A IIL ENABLE Under Voltage Lockout VDD Startup Threshold VDD Rising Threshold. 4.3 4.6 4.9 V UVLOR VDD UVLO Threshold VDD Falling Threshold. 3.95 4.25 4.55 V UVLOF VDD UVLO Hysteresis VDD 0.4 V UVLOH NOTE: The LX27901 operates at LLC mode when the Enable voltage 1.7V VIN=12V Copyright 2011 Page 2 Microsemi Rev. 1.1 Analog Mixed Signal Group 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570