MAX1778/MAX1880MAX1885 Quad-Output TFT LCD DC/DC Converters with Buffer General Description Features The MAX1778/MAX1880MAX1885 multiple-output 500kHz/1MHz Current-Mode PWM Step-Up Regulator DC-DC converters provide the regulated voltages required Up to +13V Main High-Power Output by active matrix thin-film transistor (TFT) liquid crystal 1% Accurate displays (LCD) in a low-profile TSSOP package. One High Efficiency (91%) high-power step-up converter and two low-power charge pumps convert the 2.7V to 5.5V input voltage into three Dual Regulated Charge-Pump Outputs (MAX1778/ independent output voltages. A built-in linear regulator and MAX1880MAX1882 only) Up to +40V Positive Charge-Pump Output VCOM buffer complete the power-supply requirements. Up to -40V Negative Charge-Pump Output The main step-up converter accurately generates an Low-Dropout 40mA Linear Regulator (MAX1778/ externally set output voltage up to 13V that can supply the MAX1881/MAX1883/MAX1884 only) displays row/column drivers. The converters high switch- Up to +15V LDO Input ing frequency and current-mode PWM architecture provide fast transient response and allow the use of small low- Optional Higher Current with External Transistor profile inductors and ceramic capacitors. The low-power 2.7V to 5.5V Input Supply BiCMOS control circuitry and internal 14V switch (0.35 Internal Supply Sequencing and Soft-Start N-channel MOSFET) enable efficiencies up to 91%. Power-Ready Output The dual low-power charge pumps (MAX1778/MAX1880/ Adjustable Fault-Detection Latch MAX1881/MAX1882 only) independently regulate one positive output (V ) and one negative output (V ). POS NEG Thermal Protection (+160C) These low-power outputs use external diode and capaci- 0.1A Shutdown Current tor stages (as many stages as required) to regulate output 0.7mA IN Quiescent Current voltages up to +40V and -40V. A unique control scheme Ultra-Small External Components minimizes output ripple as well as capacitor sizes for both charge pumps. Thin TSSOP Package (1.1mm max height) A resistor-programmable, 40mA, low-dropout linear regulator (MAX1778/MAX1881/MAX1883/MAX1884 only) Ordering Information provides preregulation or postregulation for any of the PART TEMP RANGE PIN-PACKAGE supplies. For higher current applications, an external transistor can be added. Additionally, the VCOM buffer MAX1778EUG -40C to +85C 24 TSSOP provides a high current output that is ideal for driving the MAX1778EUG+ -40C to +85C 24 TSSOP capacitive backplane of TFT LCD panels. The VCOM MAX1880EUG -40C to +85C 24 TSSOP buffers output voltage is preset with an internal 50% resistive-divider or can be externally adjusted for other MAX1881EUG -40C to +85C 24 TSSOP voltages. MAX1882EUG -40C to +85C 24 TSSOP The MAX1778/MAX1880MAX1885 are protected against MAX1883EUP -40C to +85C 20 TSSOP output undervoltage and thermal overload conditions by a MAX1884EUP -40C to +85C 20 TSSOP latched fault detection circuit that shuts down the device. MAX1885EUP -40C to +85C 20 TSSOP All devices are available in the ultrathin TSSOP package +Denotes lead(Pb)-free/RoHS-compliant package. (1.1mm max height). Applications Typical operating Circuit appears at end of data sheet. TFT LCD Notebook Displays Pin Configurations and Selector Guide appear at end of TFT LCD Desktop Monitor Panels data sheet. 19-1979 Rev 3 4/15MAX1778/MAX1880MAX1885 Quad-Output TFT LCD DC/DC Converters with Buffer Absolute Maximum Ratings IN, SHDN, TGND, FLTSET to GND...........................-0.3V to +6V BUFOUT, BUF+, BUF- to GND..............-0.3V to (V + 0.3V) SUPB DRVN to GND........................................-0.3V to (V + 0.3V) Continuous Power Dissipation (T = +70C) SUPN A DRVP to GND........................................-0.3V to (V + 0.3V) 20-Pin TSSOP (derate 10.9mW/C above +70C)......879mW SUPP PGND to GND.....................................................................0.3V 24-Pin TSSOP (derate 12.2mW/C above +70C)......975mW RDY, SUPB to GND................................................-0.3V to +14V Operating Temperature Range LX, SUPP, SUPN to PGND .....................................-0.3V to +14V MAX1778EUG, MAX1883EUP.........................-40C to +85C SUPL to GND..........................................................-0.3V to +18V Junction Temperature.......................................................+150C LDOOUT to GND....................................-0.3V to (V + 0.3V) Storage Temperature Range..............................-65C to +150C SUPL INTG, REF, FB, FBN, FBP to GND...............-0.3V to (V + 0.3V) Lead Temperature (soldering, 10s)...................................+300C IN FBL to GND.............-0.3V to the lower of (V + 0.3V) or +6V SUPL 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 = +3.0V, SHDN = IN, V = V = V = V = 10V, LDOOUT = FBL, BUF- = BUFOUT, BUF+ = FLTSET = TGND = IN SUPP SUPN SUPB SUPL PGND = GND, C = 0.22F, C = 1F, T = 0C to +85C. Typical values are at T = +25C, unless otherwise noted.) REF BUF A A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Supply Range V 2.7 5.5 V IN Input Undervoltage Threshold V V rising, 40mV hysteresis (typ) 2.2 2.4 2.6 V UVLO IN MAX1778/MAX1880/ 0.7 1 MAX1883 (f = 1MHz) OSC V = V = FB FBP IN Quiescent Supply Current I 1.5V, V = mA IN FBN MAX1881/MAX1882/ -0.2V MAX1884/MAX1885 0.6 1 (f = 500kHz) OSC MAX1778/MAX1880 0.4 0.7 (f = 1MHz) OSC SUPP Quiescent Current I V = 1.5V mA SUPP FBP MAX1881/MAX1882 0.3 0.5 (f = 500kHz) OSC MAX1778/MAX1880 0.4 0.7 (f = 1MHz) OSC SUPN Quiescent Current I V = -0.2V mA SUPN FBN MAX1881/MAX1882 0.3 0.5 (f = 500kHz) OSC IN Shutdown Current V = 0, V = 5V 0.1 10 A SHDN IN V = 0, V = 13V, SHDN SUPP SUPP Shutdown Current 0.1 10 A MAX1778/MAX1880/MAX1881/MAX1882 V = 0, V = 13V, SHDN SUPN SUPN Shutdown Current 0.1 10 A MAX1778/MAX1880/MAX1881/MAX1882 V = 0, V = 13V SHDN SUPL SUPL Shutdown Current 0.1 10 A MAX1778/MAX1881/MAX1883/MAX1884 SUPB Shutdown Current V = 0, V = 13V 6 13 A SHDN SUPB Maxim Integrated 2 www.maximintegrated.com