EVALUATION KIT AVAILABLE Click here to ask about the production status of specific part numbers. MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter General Description Features The MAX629 low-power DC-DC converter features an Internal, 500mA, 28V N-Channel Switch internal N-channel MOSFET switch and programmable (No External FET Required) current limiting. It is designed to supply positive or neg- Generates Positive or Negative Output Voltages ative bias voltages up to 28V from input voltages in the 80A Supply Current 0.8V to V range and can be configured for boost, OUT 1A Max Shutdown Current flyback, and SEPIC topologies. The MAX629s current-limited pulse-frequency-modula- Up to 300kHz Switching Frequency tion (PFM) control scheme provides high efficiency over a Adjustable Current Limit Allows Use of Small, wide range of load conditions. An internal, 0.5A N-channel Inexpensive Inductors MOSFET switch reduces the total part count, and a 8-Pin SO Package high switching frequency (up to 300kHz) allows for tiny surface-mount magnetics. The MAX629s combination of low supply current, logic- Ordering Information controlled shutdown, small package, and tiny external PART TEMP. RANGE PIN-PACKAGE components makes it an extremely compact and efficient high-voltage biasing solution thats ideal for battery-pow- MAX629C/D 0C to +70C Dice* ered applications. The MAX629 is available in an 8-pin MAX629ESA -40C to +85C 8 SO SO package. *Dice are tested at T = +25C, DC parameters only. A Applications Note: To order tape-and-reel shipping, add -T to the end of the part number. Positive or Negative LCD Bias Generators High-Efficiency DC-DC Boost Converters Varactor Tuning Diode Bias Pin Configuration appears at end of data sheet. Palmtop Computers 2-Cell and 3-Cell Battery-Powered Applications Typical Operating Circuit V V IN IN +2.7V +2.7V TO +5.5V TO +5.5V V OUT V V CC CC 28V SHDN LX SHDN LX -V OUT -28V ISET ISET POL FB POL MAX629 MAX629 FB REF REF GND GND POSITIVE OUTPUT VOLTAGE NEGATIVE OUTPUT VOLTAGE 19-1219 Rev 2 8/20MAX629 28V, Low-Power, High-Voltage, Boost or Inverting DC-DC Converter Absolute Maximum Ratings Supply Voltage (V to GND) .................................-0.3V to +6V Operating Temperature Range ........................... -40C to +85C CC SHDN to GND .........................................................-0.3V to +6V Junction Temperature ......................................................+150C ISET, REF, FB, POL to GND .................... -0.3V to (V + 0.3V) Storage Temperature Range ............................ -65C to +165C CC LX to GND .............................................................-0.3V to +30V Lead Temperature (soldering, 10sec) .............................+300C Continuous Power Dissipation (T = +70C) A SO (derate 5.88mW/C above +70C) ........................471mW 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. Package Information Package Code S8-4 Outline Number 21-0041 Land Pattern Number 90-0096 Thermal Resistance, Single-Layer Board: Junction to Ambient (C/W) 132 JA Junction to Case (C/W) 38 JC Electrical Characteristics (V = +5V, C = 0.1F, T = -40C to +85C, unless otherwise noted. Typical values are at T = +25C.) (Note1) CC REF A A PARAMETER CONDITIONS MIN TYP MAX UNITS V Input Voltage (Note 2) 2.7 5.5 V CC V Supply Current V = 1.3V 80 120 A CC FB V Shutdown Current SHDN = GND 0.04 1 A CC V Undervoltage Lockout 100mV hysteresis 2.3 2.5 2.65 V CC 0.8 V Input Supply Voltage (Note 2) Voltage applied to L1 (V ) V IN OUT V SHDN, POL, ISET Logic 2.4 IH V Levels V 0.4 IL Positive Output Voltage Circuit of Figure 2 28 V - V Negative Output Voltage Circuit of Figure 3 -28 V IN ISET = V 0.39 0.45 0.51 CC LX Switch-Current Limit A ISET = GND 0.20 0.25 0.33 V = 5V 0.6 1.2 CC LX On-Resistance V = 3.3V 0.7 1.4 CC LX Leakage Current V = 28V, T = +85C 0.05 2.5 A LX A Maximum LX On-Time 6.5 8.5 10.0 s POL = GND 0.7 1.0 1.3 POL = V 2.0 3.2 3.8 CC Minimum LX Off-Time s POL = GND, V < 1V 3.0 4.5 6.0 FB POL = V , V > 0.25V 3.0 4.5 6.0 CC FB POL = GND (positive T = 0C to +85C 1.225 1.250 1.275 A V output) T = -40C to +85C 1.218 1.282 A FB Set Point T = 0C to +85C -15 0 15 POL = V (negative A CC mV output) T = -40C to +85C -25 25 A FB Input Bias Current 5 50 nA T = 0C to +85C 1.225 1.250 1.275 V = 2.7V to 5.5V, A CC REF Output Voltage V no load on REF T = -40C to +85C 1.218 1.282 A Maxim Integrated 2 www.maximintegrated.com