EVALUATION KIT AVAILABLE MAX17061 8-String White LED Driver with SMBus for LCD Panel Applications General Description Features Accurate Dimming Control Using SMBus, PWM The MAX17061 is a high-efficiency driver for white lightemitting Interface diodes (LEDs). It is designed for large liquidcrystal displays Dimming Range with 8-Bit Resolution (LCDs) that employ an array of LEDs as the light source. An Adjustable DPWM Frequency with 1.5% Accuracy internal switch current-mode step-up controller drives the LED Up to Eight Parallel Strings Multiple Series- array, which can be configured for up to eight strings in parallel Connected LEDs and 10 LEDs per string. Each string is terminated with ballast 1.5% Current Regulation Accuracy Between Strings that achieves 1.5% current-regulation accuracy between Low String Feedback Voltage: 625mV at 25mA LED strings, ensuring even LED brightness. The MAX17061 has a Current wide inputvoltage range from 4.5V to 26V, and provides a fixed Full-Scale LED Current Adjustable from 15mA to 25mA or adjustable 15mA to 30mA full-scale LED current. 30mA, or Preset 25mA The MAX17061 internally generates a DPWM signal for Open and Short LED Protections accurate WLED dimming control. The DPWM frequency is Output Overvoltage Protection resistor programmable, while DPWM duty cycle is controlled 0.15 Internal HV Power MOSFET (45V max) directly from an external PWM signal or through a control Wide Input-Voltage Range from 4.5V to 26V word through the MAX17061s SMBus interface. This 500kHz/750kHz/1MHz Selectable Switching DPWM control provides a dimming range with 8-bit resolution Frequency and supports Intel display-power-saving technology (DPST) Small 28-Pin, 4mm x 4mm, Thin QFN package to maximize battery life. Ordering Information The MAX17061 has multiple features to protect the controller from fault conditions. Separate feedback loops limit the output PART TEMP RANGE PIN-PACKAGE voltage under any circumstance, ensuring safe operation. MAX17061ETI+ -40C to +85C 28 Thin QFN (4mm x 4mm) Once an open string is detected, the string is disabled while +Denotes a lead-free package. other strings operate normally. The MAX17061 also features short LED detection. The shorted strings are also disabled Simplified Operating Circuit after a 2ms fault blanking interval. The controller features cycle- L1 D1 VOUT V bycycle current limit to provide stable operation and softstart IN capability. If the MAX17061 is in current-limit condition, the step-up converter is latched off after an internal timer expires. IN V A thermal-shutdown circuit provides another level of protection. DD V LX1, 2 CC ISET The MAX17061s step-up controller features an internal PGND1, 2 R1 150m (typ), 45V (max) power MOSFET with local current- OV CCV sense amplifier for accurate cycle-by-cycle current limit. R2 This architecture greatly simplifies the external circuitry and MAX17061 PWM PWMI saves PCB space. Low-feedback voltage at each LED string PWMO 625mV (typ) at 25mA LED current helps reduce power loss FB1 FB2 GND and improve efficiency. The MAX17061 features selectable FB3 N.C. OSC FB4 switching frequency (500kHz, 750kHz, or 1MHz), which FB5 CLK SCL FB6 enables a wide variety of applications that can trade off com- DATA SDA FB7 ponent size for operating frequency. FSET FB8 EP The MAX17061 is available in a thermally enhanced 28-pin, 4mm x 4mm Thin QFN package. Applications Pin Configuration appears at end of data sheet. Notebook, Subnotebook, Handy Terminals SMBus is a trademark of Intel Corp. and Tablet Computer Displays 19-3211 Rev 1 4/14MAX17061 8-String White LED Driver with SMBus for LCD Panel Applications Absolute Maximum Ratings IN to GND ..............................................................-0.3V to +28V Continuous Power Dissipation (TA = +70C) FB , LX to GND ....................................................-0.3V to +45V 28-Pin Thin QFN (derate 16.9mW/C above +70C)...1667mW PGND to GND......................................................-0.3V to +0.3V Operating Temperature Range ...........................-40C to +85C VCC, VDD, PWMI, SDA, SCL to GND......................-0.3V to +6V Junction Temperature......................................................+150C ISET, CCV, PWMO, FSET, OSC, Storage Temperature Range .............................-60C to +150C OV to GND..............................................-0.3V to VCC + 0.3V Lead Temperature (soldering, 10s) .................................+300C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Electrical Characteristics (Circuit of Figure 1, V = 12V, C = 0.022F, R = 5.1k, V = V = V = V , R = 464k, V = GND, IN CCV CCV ISET OSC DD CC FSET PWMI T = 0C to +85C, unless otherwise noted. Typical values are at T = +25C.) A A PARAMETER CONDITIONS MIN TYP MAX UNITS V = V 4.5 5.5 IN CC IN Input Voltage Range V V = open 5.5 26.0 CC V = 26V MAX17061 is enabled at IN IN Quiescent Current 1.24 2 mA minimum brightness, no load V = V = 5V IN CC IN Quiescent Current MAX17061 is disabled, V = 12V 10 A IN MAX17061 is enabled, 6V < V < 26V, IN 4.7 5.0 5.3 0 < I < 10mA V Output Voltage V VCC CC MAX17061 is disabled, V = 12V 3.90 4.35 4.80 IN V Current Limit V is forced to 4.5V 15 40 70 mA CC CC V UVLO Threshold Rising edge, typical hysteresis = 85mV 4.00 4.25 4.45 V CC BOOST CONVERTER LX On-Resistance 20mA from LX to PGND 0.15 0.3 LX Leakage Current 45V on LX 1 A V = V 0.9 1.0 1.1 OSC CC Operating Frequency V = open 675 750 825 kHz OSC V = GND 450 500 550 OSC OSC High-Level Threshold V - 0.4 V CC OSC Midlevel Threshold 1.5 V 2.0 V CC OSC Low-Level Threshold 0.4 V PWM mode (Note 1) 10 Minimum Duty Cycle % Pulse skipping, no load (Note 1) 0 Maximum Duty Cycle 94.0 95.5 97.0 % LX Current Limit Duty cycle = 75% (Note 1) 1.6 A CONTROL INPUT SDA, SCL Logic Input-High Level 2.1 V SDA, SCL Logic Input-Low Level 0.8 V PWMI Logic Input-High Level 2.1 V PWMI Logic Input-Low Level 0.8 V Maxim Integrated 2 www.maximintegrated.com