MAX1739/MAX1839 19-1755 Rev 1 3/01 Wide Brightness Range CCFL Backlight Controllers General Description Features The MAX1739/MAX1839 fully integrated controllers are Fast Response to Input Change optimized to drive cold-cathode fluorescent lamps Wide Input Voltage Range (4.6V to 28V) (CCFLs) using the industry-proven Royer oscillator inverter architecture. The Royer architecture provides High Power-to-Light Efficiency near sinusoidal drive waveforms over the entire input Minimizes Transformer Voltage Stress range to maximize the life of CCFLs. The MAX1739/ Lamp-Out Protection with 2s Timeout MAX1839 optimize this architecture to work over a wide input voltage range, achieve high efficiency, and maxi- Buck Switch Short and Other Single-Point Fault mize the dimming range. Protection The MAX1739/MAX1839 monitor and limit the trans- Integrated Royer MOSFET Drivers Reduce former center-tap voltage when required. This ensures Transformer Pin Count minimal voltage stress on the transformer, which increases the operating life of the transformer and Buck Operation Synchronized to Royer Oscillator eases its design requirements. These controllers also Synchronizable DPWM Frequency provide protection against many other fault conditions, including lamp-out and buck short faults. Pin-Selectable Brightness Control Interface These controllers achieve 50:1 dimming range by SMBus Serial Interface (MAX1739) simultaneously adjusting lamp current and chopping Analog Interface (MAX1739/MAX1839) the CCFL on and off using a digitally adjusted pulse- width modulated (DPWM) method. CCFL brightness is controlled by an analog voltage or is set with an TM SMBus -compatible two-wire interface (MAX1739). Ordering Information The MAX1739/MAX1839 drive an external high-side N-channel power MOSFET and two low-side N-channel PART TEMP. RANGE PIN-PACKAGE power MOSFETs, all synchronized to the Royer oscilla- MAX1739EEP -40C to +85C 20 QSOP tor. An internal 5.3V linear regulator powers the MOS- MAX1839EEP -40C to +85C 20 QSOP FET drivers and most of the internal circuitry. The MAX1739/MAX1839 are available in space-saving 20-pin QSOP packages and operate over the -40C to +85C temperature range. Pin Configuration Applications Notebook/Laptop Computers TOP VIEW Car Navigation Displays REF 1 20 BATT LCD Monitors MINDAC 2 19 DH Point-of-Sale Terminals CCI 3 18 LX Portable Display Electronics CCV 4 17 BST MAX1739 SH/SUS 5 16 VL CRF/SDA 6 15 GND CTL/SCL 7 14 CS MODE 8 13 DL1 CSAV 9 12 DL2 CTFB 10 11 SYNC Pg QSOP SMBus is a trademark of Intel Corp. Pin Configurations continued at end of data sheet. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim s website at www.maxim-ic.com. EVALUATION KIT AVAILABLEWide Brightness Range CCFL Backlight Controllers ABSOLUTE MAXIMUM RATINGS VBATT to GND ...........................................................-0.3V to 30V V to GND.............................................................-6V to 12V MODE V , V to GND.................................................-0.3V to 34V V , V , V , V , V , BST SYNC CRF/SDA CRF CTL/SCL CTL SH/SUS V to V .................................................................-0.3V to 6V V to GND ............................................................-0.3V to 6V BST LX SH V to V .................................................-0.3V to (V + 0.3V) Continuous Power Dissipation (T = +70C) DH LX BST A V to GND...................................................-6V to (V + 0.3V) 20-Pin QSOP (derate 9.1mW/C above +70C)...........727mW LX BST VL to GND...................................................................-0.3V to 6V Operating Temperature .......................................-40C to +85C V , V , V , V , V to GND .........-0.3V to (VL + 0.3V) Storage Temperature.........................................-65C to +150C CCV CCI REF DL1 DL2 V , V , V to GND ................................-0.3V to 6V Lead Temperature (soldering, 10s) .................................+300C MINDAC CTFB CSAV V to GND...................................................-0.6V to (VL + 0.3V) CS 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 (V+ = 8.2V, V /SUS = V = 5.5V, MINDAC = GND, T = 0C to +85C, unless otherwise noted. Typical values are at T = +25C.) SH SH A A PARAMETER CONDITIONS MIN TYP MAX UNITS SUPPLY AND REFERENCE V = V 4.6 5.5 L BATT V Input Voltage Range V BATT V = open 6 28 L V = 28V 3.2 6 V Quiescent Current, Operation BATT BATT DH = DL1 = DL2 = open mA with Full Duty Cycle on DH V = V = 5V 3.2 6 BATT L V Quiescent Current, Shutdown SH/SUS = SH = GND 6 20 A BATT 6V < V < 28V, 0 < I < 15mA VL Output Voltage, Normal Operation BATT LOAD 5.0 5.35 5.5 V VL Output Voltage, Shutdown SH/SUS = SH = GND, no load 3.5 4.5 5.5 V VL rising (leaving lockout) 4.6 VL Undervoltage Lockout Threshold VL falling (entering lockout) 4.0 V VL Undervoltage Lockout Hysteresis 300 mV REF Output Voltage, Normal 4.5V < VL < 5.5V, I = 40A 1.96 2.00 2.04 V REF Operation V POR Threshold 0.9 2.7 V L SWITCHING REGULATOR DH Driver On-Resistance 18 DL1, DL2 Driver On-Resistance 18 Minimum DH Switching Frequency 1/t , SYNC = CS or GND, not synchronized 49 56 64 kHz DH DH Minimum Off-Time 250 375 500 ns DH Maximum Duty Cycle 98 % SYNC Synchronization Range Detect falling edges on SYNC 64 200 kHz SYNC Input Current 0 < V < 30V -2 2 A SYNC SYNC Input Threshold SYNC falling, referred to CS 400 500 600 mV SYNC Input Hysteresis Referred to the SYNC input threshold 50 100 150 mV SYNC Threshold Crossing to DL1, V = 0 to 5V, C and C < 100pF, SYNC DL 1 DL 2 120 ns DL2 Toggle Delay 50% point on SYNC to 50% point on DL1 or DL2 CS Overcurrent Threshold 408 450 492 mV 2 MAX1739/MAX1839