MAX8795A 19-0793 Rev 5 5/12 TFT-LCD DC-DC Converter with Operational Amplifiers General Description Features The MAX8795A includes a high-performance step-up 2.5V to 5.5V Input Supply Range regulator, two linear-regulator controllers, and five high- 1.2MHz Current-Mode Step-Up Regulator current operational amplifiers for active-matrix, thin-film Fast Transient Response to Pulsed Load transistor (TFT), liquid-crystal displays (LCDs). Also High-Accuracy Output Voltage (1%) included is a logic-controlled, high-voltage switch with Built-In 20V, 3A, 0.16 n-Channel MOSFET adjustable delay. High Efficiency (85%) The step-up DC-DC converter provides the regulated Linear-Regulator Controllers for V and V GON GOFF supply voltage for the panel source driver ICs. The con- High-Performance Operational Amplifiers verter is a high-frequency (1.2MHz) current-mode regu- 130mA Output Short-Circuit Current lator with an integrated 20V n-channel MOSFET that 45V/s Slew Rate allows the use of ultra-small inductors and ceramic 20MHz, -3dB Bandwidth capacitors. It provides fast transient response to pulsed Rail-to-Rail Inputs/Outputs loads while achieving efficiencies over 85%. Logic-Controlled, High-Voltage Switch with The gate-on and gate-off linear-regulator controllers Adjustable Delay provide regulated TFT gate-on and gate-off supplies Timer-Delay Fault Latch for All Regulator Outputs using external charge pumps attached to the switching Thermal-Overload Protection node. The MAX8795A includes five high-performance operational amplifiers. These amplifiers are designed to 0.6mA Quiescent Current drive the LCD backplane (VCOM) and/or the gamma- correction divider string. The device features high out- Minimal Operating Circuit put current (130mA), fast slew rate (45V/s), wide bandwidth (20MHz), and rail-to-rail inputs and outputs. VCN VCP The MAX8795A is available in a lead-free, 32-pin, thin V V QFN package with a maximum thickness of 0.8mm for IN MAIN LX ultra-thin LCD panels, as well as in a 32-pin LQFP IN FB package with 0.8mm pin pitch. STEP-UP CONTROLLER PGND COMP Applications VCP AGND Notebook Computer Displays MAX8795A DRVP LCD Monitor Panels GATE-ON VGON CONTROLLER FBP Automotive Displays SRC DEL COM SWITCH CONTROL CTL V CN Ordering Information DRN DRVN PART TEMP RANGE PIN-PACKAGE GATE-OFF V GOFF CONTROLLER SUP MAX8795AETJ+ -40C to +85C 32 Thin Q FN NEG1 FBN MAX8795AGCJ+ -40C to +105C 32 LQFP OUT1 OP1 MAX8795AGCJ/V+ -40C to +105C 32 LQFP REF POS1 REF MAX8795AGTJ+ -40C to +105C 32 TQFN NEG2 NEG4 MAX8795AGTJ/V+ -40C to +105C 32 TQFN OUT2 OUT4 OP2 OP4 +Denotes a lead(Pb)-free/RoHS-compliant package. POS2 POS4 /V denotes an automotive-qualified part. NEG5 OUT3 OUT5 OP3 OP5 POS3 POS5 BGND EP Pin Configurations appear 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 Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLETFT-LCD DC-DC Converter with Operational Amplifiers ABSOLUTE MAXIMUM RATINGS IN, CTL to AGND...................................................-0.3V to +7.5V OUT Maximum Continuous Output Current....................75mA COMP, FB, FBP, FBN, DEL, REF to AGND ....-0.3V to (V + 0.3V) LX Switch Maximum Continuous RMS Current.....................1.6A IN PGND, BGND to AGND......................................................0.3V Continuous Power Dissipation (T = +70C) A LX to PGND ............................................................-0.3V to +20V 32-Pin Thin QFN (derate 34.5mW/C above +70C) 2758mW SUP to AGND .........................................................-0.3V to +20V 32-Pin LQFP (derate 48.4mW/C above +70C)....1652.9mW DRVP to AGND.......................................................-0.3V to +36V Operating Temperature Range, E Grade ............-40C to +85C POS , NEG , OUT to AGND...................-0.3V to (V + 0.3V) Operating Temperature Range, G Grade .........-40C to +105C SUP DRVN to AGND ...................................(V - 30V) to (V + 0.3V) Junction Temperature......................................................+150C IN IN SRC to AGND.........................................................-0.3V to +40V Storage Temperature Range .............................-65C to +150C COM, DRN to AGND ................................-0.3V to (V + 0.3V) Lead Temperature (soldering, 10s) .................................+300C SRC DRN to COM............................................................-30V to +30V Soldering Temperature (reflow) .......................................+260C POS to NEG RMS Current ...................................5mA (Note 1) Note 1: See Figure 2 for the op amp clamp structure. 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, V = V = 14V, V = V = V = 0V, I = 25A, T = 0C to +85C. Typical values are at T = +25C, IN MAIN SUP PGND AGND BGND REF A A unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS IN Supply Range V (Note 2) 2.5 6.0 V IN IN Undervoltage-Lockout V V rising, typical hysteresis = 50mV 2.05 2.25 2.45 V UVLO IN Threshold V = V = 1.3V, V = 0V, FB FBP FBN 0.6 1.0 LX not switching IN Quiescent Current I mA IN V = 1.2V, V = 1.4V, V = 0V, FB FBP FBN 23 LX switching Duration-to-Trigger Fault FB or FBP below threshold or FBN above 200 ms Condition threshold T = +25C to +85C 1.238 1.250 1.262 A REF Output Voltage No external load V T = 0C to +85C 1.232 1.250 1.266 A REF Load Regulation 0 < I < 50A 10 mV LOAD REF Sink Current In regulation 10 A REF Undervoltage Lockout Rising edge typical hysteresis = 160mV 1.15 V Threshold Temperature rising +160 Thermal Shutdown C Hysteresis 15 MAIN STEP-UP REGULATOR Output Voltage Range V V 18 V MAIN IN Operating Frequency f 1000 1200 1400 kHz OSC Oscillator Maximum Duty Cycle 86 90 93 % T = +25C to +85C 1.221 1.233 1.245 A FB Regulation Voltage V No load V FB T = 0C to +85C 1.212 1.233 1.248 A FB Fault Trip Level V falling 1.10 1.14 1.17 V FB FB Load Regulation 0 < I < full load, transient only -1 % MAIN FB Line Regulation V = 2.5V to 6V 0.1 0.4 %/ V IN FB Input Bias Current V = 1.233V +100 +200 nA FB 2 MAX8795A