MAX1889 19-2485 Rev 1 10/02 Triple-Output TFT LCD Power Supply with Fault Protection General Description Features The MAX1889 provides the three regulated output volt- High-Performance Step-Up Regulator ages required for active matrix, thin-film transistor liquid Fast Transient Response crystal displays (TFT LCDs). It combines a high-perfor- Current-Mode Control Architecture mance step-up regulator with two linear-regulator con- Built-In High-Efficiency N-Channel Power trollers and multiple levels of protection circuitry for a MOSFET complete power-supply system. Current-Limit Comparator >85% Efficiency The main DC-DC converter is a high-frequency Selectable Switching Frequency (500kHz/1MHz), current-mode step-up regulator with (500kHz/1MHz) an integrated N-channel power MOSFET that allows the Internal Soft-Start use of ultra-small inductors and ceramic capacitors. With its high closed-loop bandwidth performance, the Positive Linear-Regulator Controller MAX1889 provides fast transient response to pulsed Negative Linear-Regulator Controller loads while operating with efficiencies over 85%. The Triple-Level Protection Against Smoke or Fire positive and negative linear-regulator controllers post- Input Switch Replaces Input Fuse regulate charge-pump outputs for TFT gate-on and Output Overload Detection with Timer Latch gate-off supplies. Thermal Shutdown The MAX1889 has a unique input switch control that 2.7V to 5.5V Input Operating Range can replace the typical input fuse by disconnecting the load from the input supply when a fault is detected. Ultra-Small External Components The fault detector monitors all three regulated output 1A Shutdown Current (max) voltages and can monitor current from the input supply 1mA Quiescent Current (max) as well. Additionally, the MAX1889 enters thermal shut- down when its overtemperature threshold is reached. Ultra-Thin 16-Pin QFN Package (0.8mm Maximum Thickness) The MAX1889 undervoltage lockout is set at 2.5V (max) to allow the input supply to droop under pulsed load Ordering Information conditions while avoiding any unexpected behavior when its input voltage dips momentarily. Also, the built- PART TEMP RANGE PIN-PACKAGE in soft-start and cycle-by-cycle current limiting prevent MAX1889ETE - 40C to + 85 C 16 Thin Q FN ( 5mm 5mm ) input surge currents during power-up. MAX1889EGE* - 40C to + 85 C 16 QFN ( 5m m 5mm ) The MAX1889 is available in a 16-pin thin QFN pack- * Future productContact factory for availability. age with a maximum thickness of 0.8mm for ultra-thin LCD panel design. Pin Configuration Applications Notebook Computer Displays TOP VIEW LCD Monitors 16 15 14 13 Car Navigation Displays SHDN 1 12 TGND PGND LX 2 11 MAX1889 GND FREQ 3 10 REF 4 9 FBP 56 7 8 THIN QFN (5mm x 5mm) Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. FB IN FBN GATE DRVN OCP DRVP OCNTriple-Output TFT LCD Power Supply with Fault Protection ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (T = +70C) IN, SHDN, OCN, OCP, A 16-Pin QFN (derate 19.2mW/C above +70C) .........1538mW FB, FBP, FBN, FREQ to GND ...............................-0.3V to +6V PGND to GND.....................................................................0.3V Operating Temperature Range MAX1889EGE ..................................................-40C to +85C LX to PGND ............................................................-0.3V to +14V DRVP to GND .........................................................-0.3V to +30V Junction Temperature......................................................+150C Storage Temperature Range .............................-65C to +150C REF, GATE, TGND to GND..........................-0.3V to (V + 0.3V) IN Lead Temperature (soldering, 10s) .................................+300C DRVN to GND .....................................(V - 28V) to (V + 0.3V) IN IN 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 = 3V, SHDN = IN, C = 0.22F, PGND = GND, T = 0C to +85C. Typical values are at T = +25C, unless otherwise noted.) IN REF A A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS IN Supply Range V 2.7 5.5 V IN V rising 2.55 2.7 2.85 IN Undervoltage Lockout 350mV typical IN V V UVLO (UVLO) Threshold hysteresis V falling 2.2 2.35 2.5 IN IN Quiescent Current I V = V = 1.5V, V = 0V (Note 1) 1.0 mA IN FB FBP FBN IN Shutdown Current V = 0, V = 5V 0.1 1.0 A SHDN IN REF Output Voltage V -2A < I < 50A 1.231 1.250 1.269 V REF REF Thermal Shutdown 160 C MAIN STEP-UP REGULATOR Main Output Voltage Range V V 13 V MAIN IN V = V 0.85 1 1.15 MHz FREQ IN Operating Frequency f OSC V = 0V 500 kHz FREQ Oscillator Maximum Duty Cycle 80 85 90 % FB Regulation Voltage V I = 200mA, slope = 0 (Note 2) 1.229 1.242 1.254 V FB LX FB Fault Trip Level V falling 0.95 1.0 1.05 V FB Load Regulation I = 0 to full load -1.6 % MAIN Line Regulation V = 2.7V to 5.5V 0.2 %/V IN FB Input Bias Current I V = 1.5V -100 +100 nA FB FB LX Switch On-Resistance R 250 450 m LX(ON) LX Leakage Current I V = 13V 0.01 20 A LX LX LX Current Limit I 1.6 2.1 2.8 A LIM LX RMS Current Rating Not tested 1.4 A 4096 / Soft-Start Period t s SS f OSC Soft-Start Step Size V /32 V REF POSITIVE LINEAR-REGULATOR CONTROLLER FBP Regulation Voltage V I = 0.2mA 1.213 1.25 1.288 V FBP DRVP FBP Fault Trip Level V falling 0.96 1.0 1.04 V FBP FBP Input Bias Current I V = 1.25V -50 +50 nA FBP FBP FBP Effective Transconductance V = 10V, I = 0.1mA to 2mA 75 mS DRVP DRVP 2 MAX1889