MAX1534 19-2662 Rev 0 10/02 High-Efficiency, Triple-Output, Keep-Alive Power Supply for Notebook Computers General Description Features The MAX1534 is a high-efficiency, triple-output power One Switching and Two Linear Regulators supply for keep-alive (always on) voltage rails. The Switching Regulator 500mA buck regulator with an internal current-limited +4.5V to +24V Input Voltage Range 0.5 PMOS steps down the battery or wall adapter supply rail to a fixed 5V or an adjustable output voltage. Over 95% Efficiency Two integrated low-voltage linear regulators follow this Up to 500mA Output Current output and provide two independent preset output volt- Up to 200kHz Switching Frequency ages of 3.3V and 1.8V, or adjustable output voltages. Fixed 5V or Adjustable Output Voltage Internal 0.5 PMOS Switch The buck regulator utilizes a peak current-limit, pulse- frequency modulation (PFM) architecture for highest 100% Maximum Duty Cycle for Low-Dropout light-load efficiency to conserve battery life. High Operation switching frequencies (up to 200kHz) allow the use of Two Low-Dropout Linear Regulators tiny surface-mount inductors and output capacitors. Up to 160mA Output Current (Each) Operation to 100% duty cycle minimizes dropout volt- 3.3V/Adj Output Voltage for OUT1 age (250mV at 500mA). 1.8V/Adj Output Voltage for OUT2 The low-dropout linear regulators use an internal P-channel metal-oxide (PMOS) pass transistor to mini- 1.5% Accurate Output Voltage mize supply current and deliver up to 160mA each of 4% Accurate Shutdown for Low Battery continuous current. Detection The MAX1534 includes a power-OK (POK) signal that Thermal Shutdown Protection indicates all outputs are in regulation. The 4% accurate threshold of the SHDN input permits its use as a low- POK Output battery detector. 1mW Typical Standby Power The MAX1534 is available in a small 16-pin thin QFN (4mm 4mm) package, occupying 33% less board space than discrete solutions. Applications Ordering Information Notebook and Sub- Hand-Held Devices PART TEMP RANGE PIN-PACKAGE Notebook Computers Keep-Alive Supplies MAX1534ETE -40C to +85C 16 Thin QFN (4mm 4mm) Wake-On LAN Standby Supplies 2 to 4 Li+ Cells Battery- Pin Configuration appears at end of data sheet. Powered Devices Typical Operating Circuit V = +7V TO +24V IN IN SHDN POK BP FB3 PRESET ILIM V = +5V ALWAYS LX OUT3 FB1 MAX1534 FB2 V = +3.3V ALWAYS OUT1 OUT1 LDOIN V = +1.8V ALWAYS OUT2 OUT2 GND 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.High-Efficiency, Triple-Output, Keep-Alive Power Supply for Notebook Computers ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (T = +70C) IN, ILIM, PRESET, SHDN to GND...........................-0.3V to +25V A FB1, FB2, FB3, LDOIN, BP to GND..........................-0.3V to +6V 16-Pin Thin QFN (derate 16.9mW/C above +70C)............................................................1349mW OUT1, OUT2, POK to GND ...................-0.3V to (V + 0.3V) LDOIN LX to GND.......................................................-2V to (V + 0.3V) Operating Temperature Range ...........................-40C to +85C IN Junction Temperature......................................................+150C OUT1, OUT2 Short Circuit to GND.............................Continuous Peak IN Current........................................................................2A Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Maximum IN DC Current...................................................500mA 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 = 12V, ILIM = GND, PRESET = GND, T = 0C to +85C, unless otherwise noted. Typical values are at T = IN A A +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Voltage Range V 4.5 24 V IN Input Supply Current I No load, FB3 = 5.2V, LDOIN = GND 15 30 A IN Input Supply Current in I N o load , FB3 = V = 4.5V, L DO IN = G N D 60 110 A IN(DROP) IN Dropout Shutdown Supply Current SHDN = GND 3.5 7 A V rising 3.6 4.0 4.4 IN Input UVLO Threshold V V UVLO V falling 3.5 3.9 4.3 IN BUCK REGULATOR T = +25C to +85C 4.92 5.00 5.08 FB3 Voltage Accuracy (Preset A PRESET = GND V Mode) (Note 1) T = 0C to +85C 4.90 5.00 5.10 A T = +25C to +85C 0.985 1.00 1.015 FB3 Set Voltage (Adjustable A V PRESET = IN V FB3 Mode) (Note 1) T = 0C to +85C 0.98 1.00 1.02 A FB3 Bias Current I V = 5.5V 3.5 6.25 A FB3 FB3 LX Switch Minimum Off-Time t 0.22 0.42 0.62 s OFF(MIN) LX Switch Minimum On-Time t 0.50 s ON(MIN) LX Switch Maximum On-Time t 910 11 s ON(MAX) V = 6V 0.5 1.0 IN LX Switch On-Resistance R LX V = 4.5V 0.6 1.2 IN ILIM = IN 800 1000 1200 LX Current Limit I mA LX(PEAK) ILIM = GND 425 500 575 LX Zero-Crossing Threshold -75 +75 mV LX Zero-Crossing Timeout LX does not rise above threshold 30 s T = +25C1 V = 24V, not A IN LX Switch Leakage Current A switching T = 0C to +85C10 A Dropout Voltage V I = 500mA 250 mV OUT3(DROPOUT) LX(DC) Line Regulation V = 8V to 24V, I = 200mA 0.1 %/V IN LX(DC) Load Regulation I = 80mA to 400mA 0.9 % LX(DC) LINEAR REGULATORS LDOIN Input Voltage V 2.5 5.5 V LDOIN LDOIN Undervoltage Lockout V V rising, hysteresis = 40mV typ 2.15 2.4 V UVLO(LDO) LDOIN 2 MAX1534