MAX685 19-1353 Rev 1 6/03 Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD General Description Features The MAX685 DC-DC converter provides low-noise dual Dual Output Using a Single Inductor outputs for powering CCD imaging devices and LCDs. Low-Noise Output, 30mVp-p Ripple This device uses a single inductor to provide indepen- dently regulated positive and negative outputs. Output Voltages up to 24V and down to -9V Integrated power switches are included in a small 24- (up to 45V and down to -16V with added Pin 4mm x 4mm Thin QFN package to save space and components) reduce cost. A 16-pin QSOP package is also available. Internal Switches in a Small 24-Pin 4mm x 4mm Each output delivers up to 10mA from a +2.7V to +5.5V Thin QFN Package input voltage range. Output voltages are set indepen- dently up to 24V and down to -9V. With a few additional 220kHz/400kHz Fixed-Frequency PWM Operation low-cost components, the output voltages can be set at Frequency Can Be Synchronized to External up to 45V and down to -16V. Output ripple magnitude is Clock 30mVp-p. The MAX685 uses a fixed-frequency, pulse- width-modulated (PWM) control scheme at 220kHz or Power-OK Indicator 400kHz to permit output noise filtering and to reduce Selectable Power-On Sequencing the size of external components. The frequency can also be synchronized to an external clock signal 0.1A Logic-Controlled Shutdown between 200kHz and 480kHz. The MAX685 has a power-OK indicator output (POK) Ordering Information that signals when both outputs are within regulation. A logic-controlled shutdown completely turns off both out- PART TEMP RANGE PIN-PACKAGE puts and reduces supply current to 0.1A. The user MAX685EEE -40C to +85C 16 QSOP can also set which output turns on first. MAX685ETG -40C to +85C 24 TQFN The preassembled MAX685 evaluation kit is available to reduce design time. Typical Operating Circuit Applications Camcorders LCDs Digital Cameras CCD Imaging Devices INPUT Notebooks POSITIVE 2.7V TO 5.5V OUTPUT VP LXN Pin Configuration UP TO 24V, V DD 10mA TOP VIEW FBP ON SHDN OFF N.C. 1 18 N.C. MAX685 NEGATIVE SYNC LXP 2 17 OUTPUT VP PGND OPTIONAL DOWN TO -9V, 10mA VP 3 16 PGND POS MAX685 POK 4 15 PGND SEQ FBN NEG SEQ 5 14 FBP POWER-OK SHDN 6 13 REF POK GND REF INDICATOR 24-TQFN (4mm x 4mm) 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. EVALUATION KIT MANUAL FOLLOWS DATA SHEET SYNC 7 24 I.C. V 23 LXP DD 8 N.C. 9 22 LXP N.C. 10 21 LXN GND 11 20 LXN FBN 12 19 I.C.Dual-Output (Positive and Negative), DC-DC Converter for CCD and LCD ABSOLUTE MAXIMUM RATINGS V , VP to GND........................................................-0.3V to +6V Continuous Power Dissipation (T = +70C) DD A PGND to GND .......................................................-0.3V to +0.3V 16-Pin QSOP (derate 8.3mW/C above +70C)............667mW V to VP...............................................................-0.3V to +0.3V 24-Pin TQFN (derate 20.8mW/C above +70C) ........1667mW DD LXN, POK to GND ..................................................-0.3V to +30V Operating Temperature Range ...........................-40C to +85C LXP to V ..............................................................-15V to +0.3V Junction Temperature......................................................+150C DD REF, SEQ, SHDN to GND...........................-0.3V to (V + 0.3V) Storage Temperature Range .............................-65C to +165C DD FBP, FBN, SYNC to GND .........................................-0.3V to +6V 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 (V = VP = 5V, T = 0C to +85C unless otherwise noted. Typical values are at T = +25C.) DD A A PARAMETER CONDITIONS MIN TYP MAX UNITS Input Voltage Range V = VP 2.7 5.5 V DD Positive Output Voltage Range VP 24 V Negative Output Voltage Range V = 5.5V (Note 1) -9 -1.27 V DD V = 4.5V, V 14.25V, V -7.125V, DD OUT+ OUT- Output Current 10 mA Figure 3 LX Current Limit T = +25C 440 mA A LXP, LXN On-Resistance V = 4.5V 0.6 2 DD Quiescent Current SYNC = V 0.8 mA DD Idle Quiescent Current V = 1.35V, V = -0.1V 300 500 A FBP FBN Line Regulation V = 4.5V to 5.5V 0.2 %/V DD Load Regulation I = 0 to 10mA, C1 = 10F 0.13 %/mA OUT Output Voltage Ripple C3 = C4 = 10F, I = 5mA 30 mVp-p LOAD SHUTDOWN (SHDN) Shutdown Supply Current SYNC = SEQ = SHDN = GND 0.1 10 A UNDERVOLTAGE LOCKOUT UVLO Threshold V = rising 2.35 2.5 2.65 V DD UVLO Hysteresis 50 mV REFERENCE VOLTAGE V Output Voltage No load 1.23 1.250 1.27 V REF V Load Regulation 0 < I < 50A -2 mV REF REF FB INPUTS FBP Threshold Voltage No load 1.21 1.24 1.27 V FBN Threshold Voltage No load -16 10 36 mV FBP, FBN Input Leakage Current 0.01 0.1 A LOGIC INPUTS (SEQ, SHDN, SYNC) Logic-Low Input 2.7V < V < 5.5V 0.3 x V V DD DD Logic-High Input 2.7V < V < 5.5V 0.7 x V V DD DD Input Bias Current 0.1 1 A 2 MAX685