EVALUATION KIT AVAILABLE MAX17129/MAX17149 Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter General Description Features The MAX17129/MAX17149 are high-efficiency drivers Independently Controlled Dual Paths for white LEDs. They are designed for small- to medium- 3V to 26V Input Supply Voltage sized LCDs that employ an array of LEDs as the light Up to Six Parallel Strings of Multiple Series- source. An internal switch step-up controller with Quick- Connected LEDs PWM drives the LED array, which can be configured for up to 6 strings in parallel and either 11 LEDs (MAX17129) Step-Up Regulator with Quick-PWM Control Scheme or 6 LEDs in series (MAX17149) per string. Each string Two-Level Selectable Switching Frequency is terminated with a ballast that achieves 2% current- regulation accuracy, ensuring even LED brightness and 0.25 Internal HV Power MOSFET (48V max) provides an adjustable 10mA to 45mA full-scale LED Low String Feedback Voltage: 275mV at 20mA LED current. The devices have a wide input voltage range of Current 6V to 26V. The MAX17129 integrates an LDO to simplify Full-Scale LED Current Adjustable from 10mA to applications that have a single high-voltage supply. The 45mA devices also feature a low-input-voltage mode for applica- tions that have a 3V to 5.5V supply voltage. 2% Current-Regulation Accuracy Between Strings The devices support both PWM and hybrid dimming Support PWM and Hybrid Dimming Mode mode. In PWM dimming mode, the external PWM signal 100:1 Dimming Ratio directly controls the brightness of LEDs. The dimming fre- 100Hz to 25kHz Dimming Frequency for PWM quency ranges from 100Hz to 25kHz with 400ns minimum on-time. In hybrid dimming mode, the LED current ampli- Dimming Mode tude can be adjusted to 25% of full-scale LED current to Open- and Short-LED Protection improve system efficiency when brightness is low. Output-Overvoltage Protection The devices have multiple features to protect the Small 16-Pin, 3mm x 3mm Thin QFN Package controller from fault conditions. Separate voltage- feedback loops limit the output voltage to safe operation. Applications The open- and short-LED detection shuts down the faulty string while keeping other strings operating normally. Notebook, Subnotebook, and Tablet Computer Displays The devices feature cycle-by-cycle current limit on the Handy Terminals internal switch to provide consistent operation and soft- start capability. If the devices are in current-limit condition, the step-up converter is latched off after an internal timer Ordering Information expires. A thermal-shutdown circuit provides another level of protection and prevents ICs from damage. PART TEMP RANGE PIN-PACKAGE The ICs step-up controller features an internal 0.25 MAX17129ETE + -40C to +85C 16 Thin QFN-EP* (typ), 48V (max) power MOSFET with lossless current MAX17149ETE+ -40C to +85C 16 Thin QFN-EP* sense and accurate cycle-by-cycle current limit. The +Denotes lead(Pb)-free/RoHS-compliant package. Quick-PWM control architecture provides fast load-tran- *EP = Exposed pad. sient response without requiring an external loop com- pensation component, simplifies the external circuitry, and saves board area. The Quick-PWM control scheme has Simplified Operating Circuit appears at end of data sheet. constant off-time and adjustable pseudo-fixed frequency, which enables a wide variety of applications that can trade off component size for operating frequency. Low feedback voltage at each LED string (275mV typ at 20mA LED current) helps reduce power loss and improve efficiency. The ICs are available in a 16-pin, thin QFN package with Quick-PWM is a trademark of Maxim Integrated Products, Inc. 0.5mm lead spacing. The package is 3mm x 3mm with a maximum thickness of 0.8mm for ultra-thin LCD panel design. 19-5676 Rev 2 11/14MAX17129/MAX17149 Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up Converter Absolute Maximum Ratings FSEL, IN, BRT, EN to GND ...................................-0.3V to +28V Operating Temperature Range..............................-40C to +85C FB , LX, OVP to PGND..........................................-0.3V to +48V Junction Temperature.......................................................+150C PGND to GND.......................................................-0.3V to +0.3V Storage Temperature Range...............................-60C to +150C V to GND..............................................................-0.3V to +6V ESD CC ISET to GND................................................ -0.3V to V + 0.3V HBM..................................................................................2kV CC LX Switch Continuous RMS Current......................................1.6A MM..................................................................................200V Continuous Power Dissipation (T = +70C) Lead Temperature (soldering, 10s)...................................+300C A 16-Pin Thin QFN (derate 14.7mW/C above +70C)..1176mW Soldering Temperature (reflow)........................................+260C 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, R = 100k, T = 0C to +85C, unless otherwise noted. Typical values are at T = +25C.) (Note 1) IN ISET A A PARAMETER CONDITIONS MIN TYP MAX UNITS IN not connected to V 6 26 CC IN Input Voltage Range V IN connected to V 3.0 5.5 CC V = 3V, V = 26V, no external loads 3.2 4 mA EN IN IN Standby Current V = 0V, V = 26V 0.1 5 A EN IN V Output Voltage V = 3V, 0 < I < 10mA 3.6 3.8 4.0 V CC EN VCC V Current Limit V is forced to 3.5V IN not connected to V 15 30 45 mA CC CC CC V UVLO Threshold Rising edge, typical hysteresis = 100mV 2.75 2.8 2.85 V CC Rising edge, typical hysteresis = 100mV IN UVLO Threshold 5.5 5.75 5.9 V IN not connected to V CC STEP-UP CONVERTER LX On-Resistance 100mA from LX to PGND 250 500 m LX Leakage Current V = 40V, T = +25C 0.05 1 A LX A FSEL = GND, V = 12V, V = 22V 450 500 550 IN OVP Off-Time ns FSEL = V , V = 12V, V = 22V 900 1000 1100 CC IN OVP LX Peak Current Limit Duty cycle = 75% 2.5 3 3.5 A Minimum On-Time 50 ns MAX17129 only 15 16.5 18 V Minimum Output Regulation Voltage MAX17149 only 6.8 8.3 9.8 V MAX17129 only 41.5 43 44.5 V Maximum Output Regulation Voltage MAX17149 only 23.9 25.4 26.9 V INPUT LEAKAGE/BIAS CURRENTS 0.3V < V < 3.5V, T = +25C 6 EN A EN Bias Current A 4.1V < V < 26V, T = +25C 110 EN A 0.3V < V < 3.5V, T = +25C 15 BRT A BRT Bias Current A 4.1V < V < 26V, T = +25C 2000 BRT A EN Input Impedance 750 1500 k MAX17129 only V = 40V, V = 0.75V 15 50 A OVP FB OVP Input Current MAX17149 only V = 20V, V = 0.75V 7.5 25 A OVP FB 0.3V < V < 3.5V, T = +25C 6 FSEL A FSEL Bias Current A 4.1V < V < 26V, T = +25C 2000 FSEL A Maxim Integrated 2 www.maximintegrated.com