MAX1997/MAX1998 19-2638 Rev 0 10/02 Quintuple/Triple-Output TFT LCD Power Supplies with Fault Protection and VCOM Buffer General Description Features The MAX1997/MAX1998 provide the voltages required for 2.7V to 5.5V Input Supply Range active-matrix, thin-film transistor liquid-crystal displays Adjustable (Up to +13V) Output Voltage for (TFT LCDs). Both combine a high-performance step-up Source-Driver ICs regulator with two linear-regulator controllers, input pro- tection switch control, and flexible sequence program- Integrated High-Efficiency Power MOSFET ming. The MAX1997 contains two additional linear- Linear-Regulator Controllers for TFT Gate-On and regulator controllers and a VCOM buffer. The MAX1997/ MAX1998 can operate from input supplies of 2.7V to 5.5V Gate-Off Supplies and feature multiple levels of protection circuitry, making High-Current VCOM Buffer (MAX1997 Only) them complete power-supply systems for displays. Two Additional Linear-Regulator Controllers The main DC-DC converter provides the regulated supply (MAX1997 Only) voltage for the displays source-driver ICs. The converter is a high-frequency (up to 1.5MHz) step-up regulator with Programmable Power-Up Sequencing an integrated 14V N-channel MOSFET that allows the use Multiple Overload Protection with Thermal of ultra-small inductors and ceramic capacitors while Shutdown achieving efficiencies over 85%. Its current-mode control architecture provides fast transient response to pulsed 1A Shutdown Current loads. Internal soft-start and cycle-by-cycle current limit 32-Pin/20-Pin Thin QFN Packages help prevent input surge currents. The positive and negative linear-regulator controllers postregulate charge-pump outputs for TFT gate-on and gate-off supplies. Both linear-regulator controllers, as well Ordering Information as the step-up regulator, have supply-sequencing control inputs. The three outputs can be sequenced in any order PART TEMP RANGE PIN-PACKAGE by selecting the appropriate external components. MAX1997ETJ -40C to +85C 32 Thin QFN 5mm x 5mm The MAX1997 features a high-current backplane driver MAX1998ETP -40C to +85C 20 Thin QFN 5mm x 5mm (VCOM). This buffer provides peak currents exceeding 300mA (typ) and requires only a 0.47F output filter capacitor. The MAX1997s two additional linear-regulator controllers can be used to build the gamma reference voltage and a logic supply. Pin Configurations The MAX1997/MAX1998 have a unique input switch con- trol that can replace the typical input supply fuse. When a TOP VIEW fault is detected, the regulator is disconnected from the input supply. The fault detector monitors all the regulated output voltages and the current from the input supply. In addition, the MAX1997/MAX1998 enter shutdown when PGND 1 15 TGNDA the internal over-temperature threshold is reached. 2 14 LX CT The MAX1997 is available in a 32-pin thin QFN package 3 13 DRVP ONN MAX1998 and the MAX1998 is available in a 20-pin thin QFN pack- 4 12 FBP ONP age. Both packages have a maximum thickness of 11 ON2 5 FB 0.8mm suitable for ultra-thin LCD panels. Applications Notebook Computer Displays THIN QFN 5mm 5mm LCD Monitors Car Navigation Displays Pin Configurations continued at end of data sheet. 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. DRVN 6 20 FREQ FBN 7 19 IN 8 DRVA 18 GATE REF 9 17 OCP OCN GND 10 16Quintuple/Triple-Output TFT LCD Power Supplies with Fault Protection and VCOM Buffer ABSOLUTE MAXIMUM RATINGS MAX1997 Continuous Power Dissipation (T = +70C) IN, SHDN, FB, FBP, FBN, FB1, FB2, ONDC, A ONP, ONN, ON2, TGNDA, TGNDB to GND.............-0.3V to +6V 32-Pin Thin QFN (derate 21.2mW/C above +70C)............................1702mW PGND to GND .....................................................................0.3V LX, V to GND....................................................-0.3V to +14V MAX1998 Continuous Power Dissipation (T = +70C) A DDB 20-Pin Thin QFN DRVP, DRV1, DRV2, DRVA to GND .......................-0.3V to +30V REF, FREQ, GATE, OCN, OCP, CT, (derate 20mW/C above +70C)...............................1600mW Operating Temperature Range ...........................-40C to +85C PFLT to GND ..................................................-0.3V to V + 0.3V IN DRVN to GND ..........................................V - 28V to V + 0.3V Junction Temperature......................................................+150C IN IN Storage Temperature Range .............................-65C to +150C FBPB, FBNB, OUTB to GND.......................-0.3V to V + 0.3V DDB OUTB Continuous Output Current ..................................100mA Lead Temperature (soldering, 10s) .................................+300C 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 = 3V, V = 10V, SHDN = ONDC = FREQ = IN, C = 0.22F, PGND = GND, T = 0C to +85C. IN DDB REF A Typical values are at T = +25C, unless otherwise noted.) A PARAMETER CONDITIONS MIN TYP MAX UNITS IN Supply Range 2.7 5.5 V V rising 2.5 2.7 2.9 IN 350mV (typ) IN Undervoltage Lockout Threshold V hysteresis V falling 2.2 2.35 2.5 IN V = V = V = V = 1.5V, V = 0 FB FBP FB1 FB2 FBN 0.54 1.25 (MAX1997 only) IN Quiescent Current (Note 1) mA V = V = 1.5V, V = 0 (MAX1998 only) 0.476 1 FB FBP FBN IN Shutdown Current V = 0, V = 5.5V 0.1 1 A SHDN IN -2A < I < 50A 1.231 1.250 1.269 REF REF Output Voltage V -2A < I < 75A 1.225 1.250 1.275 REF Thermal Shutdown 160 C OVERCURRENT COMPARATOR Input Offset Voltage V = V = 1.5V to 0.8V V -5 +5 mV OCN OCP IN Input Bias Current V = V = 0.8V V -50 +50 nA OCN OCP IN 0.8 OCN, OCP Input Common-Mode Range 1.5 V V IN FAULT TIMER PFLT = GND (MAX1997 only) 21.8 Fault Timer Period ms PFLT unconnected (MAX1997 only) 43.6 PFLT = IN, or MAX1998 87.2 GATE Output Sink Current During Slew V = 1.5V during turn-on transition 5 10 15 A GATE GATE Output Pulldown Resistance V < 0.5V 200 GATE GATE Output Pullup Resistance 200 MAIN STEP-UP REGULATOR Output Voltage Range V 13 V IN FREQ = IN 1.5 Operating Frequency FREQ unconnected 0.637 0.75 0.863 MHz FREQ = GND 0.375 2 MAX1997/MAX1998