EVALUATION KIT AVAILABLE MAX17127 Six-String WLED Driver with Integrated Step-Up Converter General Description Features 5V to 26V Input Supply Voltage The MAX17127 is a high-efficiency driver for white light- emitting diodes (LEDs). It is designed for large liquid- Up to Six Parallel Strings Multiple Series-Connected LEDs crystal displays (LCDs) that employ an array of LEDs as the light source. An internal switch current-mode step-up 250kHz to 1MHz Adjustable Switching Frequency converter drives the LED array, which can be configured 0.12 Internal HV Power MOSFET (48V max) for up to six strings in parallel and 13 LEDs per string. Low String Feedback Voltage: 480mV at 20mA LED Each string is terminated with ballast that achieves 2% Current current-regulation accuracy, ensuring even LED bright- Full-Scale LED Current Adjustable from 10mA to ness. The MAX17127 has a wide input voltage range 30mA from 5V to 26V, and provides adjustable 10mA to 30mA 2% Current-Regulation Accuracy Between Strings full-scale LED current. 400ns Minimum String On-Time The MAX17127 can implement brightness control through 100Hz to 25kHz PWM Input Range the PWM signal input, and LED current is directly controlled by the external dimming signals frequency and Open and Short LED Protection duty cycle. Output Overvoltage Protection The MAX17127 has multiple features to protect the Thermal Shutdown controller from fault conditions. Once an open/short string Small 20-Pin, 4mm x 4mm Thin QFN Package is detected, the fault string is disabled while other strings can still operate normally. The controller features cycle- Ordering Information by-cycle current limit to provide constant operation and PART TEMP RANGE PIN-PACKAGE soft-start capability. If the MAX17127 is in current-limit condition, the step-up converter is latched off after an MAX17127ETP+ -40C to +85C 20 TQFN-EP* internal timer expires. A thermal-shutdown circuit pro- +Denotes a lead(Pb)-free/RoHS-compliant package. vides another level of protection. When thermal shutdown *EP = Exposed pad. happens, the MAX17127 is latched off. The MAX17127s step-up controller features an internal Applications 0.12 (typ), 48V (max) power MOSFET with local current- Notebook, Subnotebook, and Tablet Computer sense amplifier for accurate cycle-by-cycle current limit. Displays This architecture greatly simplifies the external circuitry Handy Terminals and saves PCB space. Low-feedback voltage at each LED string helps reduce power loss and improve efficiency. The MAX17127 features resistor-adjustable switching frequency from 250kHz to 1MHz, which enables a wide variety of applications that can trade off component size for operating frequency. The MAX17127 is available in a thermally enhanced, lead-free, 20-pin, 4mm x 4mm thin QFN package. Simplified Operating Circuit appears at end of data sheet. 19-5164 Rev 1 11/14MAX17127 Six-String WLED Driver with Integrated Step-Up Converter Absolute Maximum Ratings V to AGND ........................................................-0.3V to +30V Operating Temperature Range ........................... -40C to +85C IN FB , SW to PGND ................................................-0.3V to +52V Junction Temperature ......................................................+150C PGND to AGND ....................................................-0.3V to +0.3V Storage Temperature Range ............................ -60C to +150C V , PWM, EN, FPO, I.C. to AGND ....................-0.3V to +6V ESD DDIO COMP, ISET, R FPWM, OVP, FSLCT HBM ...................................................................................2kV to AGND .............................................. -0.3V to V + 0.3V MM ...................................................................................200V DDIO SW Switch Maximum Continuous RMS Current ..................1.6A Lead Temperature (soldering, 10s) .................................+300C Continuous Power Dissipation (T = +70C) Soldering Temperature (reflow) .......................................+260C A TQFN (derate 16.9mW/NC above +70C) ................1349mW 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 = 0.51nF, C = 4.7F, R = 82.5k, R = 180k, R = 100k, L = 10H, IN COMP COUT COMP ISET FSLCT T = 0C to +85C, unless otherwise noted. Typical values are at T = +25C.) A A PARAMETER CONDITIONS MIN TYP MAX UNITS V Input Voltage Range 5 26 V IN MAX17127 is enabled, V = 3.3V, V = 26V 2.7 3.2 mA EN IN V Quiescent Current IN MAX17127 is disabled, EN = AGND 5 10 A MAX17127 is enabled, V = 3.3V, EN 4.85 5 5.15 5.4V < V < 26V, 0A < I < 10mA IN VDDIO V V Output Voltage MAX17127 is enabled, V = 3.3V, V = 5V, I = 10mA, DDIO EN IN VDDIO 4.6 4.75 dropout condition MAX17127 is disabled, EN = AGND, 0A < I < 50A 3.1 3.7 4.1 V VDDIO V Current Limit V is forced to 4.2V 25 45 70 mA DDIO DDIO V UVLO Threshold Rising edge, typical hysteresis = 250mV 3.90 4.00 4.10 V DDIO Falling edge 4.3 4.5 4.7 V UVLO Threshold V IN Rising edge 4.55 4.75 4.95 BOOST CONVERTER SW On-Resistance 20mA from SW to PGND 0.12 0.25 SW Leakage Current 40V on SW, T = +25C 1 A A R = 100k 0.95 1.0 1.05 FSLCT Operating Frequency MHz R = 400k 0.225 0.25 0.275 FSLCT R Range Operating range 90 500 k FSLCT Maximum Duty Cycle At f = 1MHz 91 95 % SW Minimum On-Time (Note 1) 50 80 ns SW Current Limit Duty cycle = 75% 3.12 3.9 4.7 A CONTROL INPUT PWM, EN Logic-Input 2.1 V High Level PWM, EN Logic-Input Low 0.8 V Level EN Pulldown Resistor 120 200 280 k Maxim Integrated 2 www.maximintegrated.com