EVALUATION KIT AVAILABLE MAX17544 4.5V42V, 3.5A, High-Efficiency, Synchronous Step-Down DC-DC Converter With Internal Compensation General Description Benefits and Features The MAX17544 high-efficiency, high-voltage, synchronous Reduces External Components and Total Cost step-down DC-DC converter with integrated MOSFETs No SchottkySynchronous Operation operates over 4.5V to 42V input. The converter can deliver Internal Compensation for Any Output Voltage Built-In Soft-Start up to 3.5A and generates output voltages from 0.9V up to 0.9 x V . The feedback (FB) voltage is accurate to within All-Ceramic Capacitors, Compact Layout IN 1.1% over -40C to +125C. Reduces Number of DC-DC Regulators to Stock The MAX17544 uses peak-current-mode control. The Wide 4.5V to 42V Input device can be operated in pulse-width modulation (PWM), Adjustable 0.9V to 0.9 x V Output IN pulse-frequency modulation (PFM), or discontinuous 100kHz to 2.2MHz Adjustable Switching Frequency conduction mode (DCM) control schemes. with External Synchronization The device is available in a 20-pin (5mm x 5mm) TQFN Reduces Power Dissipation package. Simulation models are available. Peak Efficiency > 90% PFM/DCM Enables Enhanced Light-Load Applications Efficiency 2.8A Shutdown Current Industrial Power Supplies Distributed Supply Regulation Operates Reliably in Adverse Industrial Environments Peak Current-Limit Protection High-Voltage Single-Board Systems Built-In Output Voltage Monitoring with RESET Base Station Power Supply Programmable EN/UVLO Threshold General-Purpose Point-of-Load Monotonic Startup into Prebiased Load Overtemperature Protection High Industrial -40C to +125C Ambient Operating Ordering Information appears at end of data sheet. Temperature Range/-40C to +150C Junction Temperature Range Typical Application Circuit5V, 500kHz Switching Frequency V IN (7.5V TO 42V) C1 C8 EN/UVLO V V V 2.2F 2.2F IN IN IN BST C5 L1 RT V 0.1F OUT 10H LX 5V, 3.5A SYNC LX C4 C9 MAX17544 R3 MODE 22F 22F 100k LX V CC C2 FB 2.2F SGND R4 RESET 22.1k CF SS PGND PGND PGND C3 f = 500kHz SW 12000pF 19-7055 Rev 1 7/16MAX17544 4.5V42V, 3.5A, High-Efficiency, Synchronous Step-Down DC-DC Converter With Internal Compensation Absolute Maximum Ratings V to PGND .........................................................-0.3V to +48V SGND to PGND.................................................... -0.3V to +0.3V IN EN/UVLO to SGND ...............................................-0.3V to +48V LX Total RMS Current ........................................................5.6A LX to PGND................................................-0.3V to (V + 0.3V) Output Short-Circuit Duration ....................................Continuous IN BST to PGND ........................................................-0.3V to +53V Continuous Power Dissipation (T = +70C) (multilayer board) A BST to LX .............................................................-0.3V to +6.5V TQFN (derate 30.3mW/C above T = +70C) ......2424.2mW A BST to V ...........................................................-0.3V to +48V Junction Temperature ......................................................+150C CC CF, RESET, SS, MODE, SYNC, Storage Temperature Range ............................ -65C to +160C RT to SGND .....................................................-0.3V to +6.5V Lead Temperature (soldering, 10s) .................................+300C FB to SGND .........................................................-0.3V to +1.5V Soldering Temperature (reflow) .......................................+260C V to SGND .......................................................-0.3V to +6.5V CC 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. Junction temperature greater than +125C degrades operating lifetimes. Package Thermal Characteristics (Note 1) TQFN Junction-to-Ambient Thermal Resistance ( ) ..........30C/W JA Junction-to-Case Thermal Resistance ( ) .................2C/W JC Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Electrical Characteristics (V = V = 24V, R = 40.2k (500kHz), C = 2.2F, V = V = V = V = 0V, LX = SS = RESET = IN EN/UVLO RT VCC PGND SGND MODE SYNC open, V to V = 5V, V = 1V, T = -40C to +125C, unless otherwise noted. Typical values are at T = +25C. All voltages are BST LX FB A A referenced to SGND, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS INPUT SUPPLY (V ) IN Input Voltage Range V 4.5 42 V IN Input Shutdown Current I V = 0V (shutdown mode) 2.8 4.5 IN-SH EN/UVLO V = 1V, MODE = RT = open 118 A FB I Q PFM V = 1V, MODE = open 162 FB Input Quiescent Current I DCM mode, V = 0.1V 1.16 1.8 Q-DCM LX mA Normal switching mode, f = 500kHz, SW I 9.5 Q PWM V = 0.8V FB ENABLE/UVLO (EN/UVLO) V V rising 1.19 1.215 1.26 ENR EN/UVLO EN/UVLO Threshold V V V falling 1.068 1.09 1.131 ENF EN/UVLO EN/UVLO Input Leakage Current I V = 0V, T = +25C -50 0 +50 nA EN EN/UVLO A LDO 6V < V < 42V, I = 1mA IN VCC V Output Voltage Range V 4.75 5 5.25 V CC CC 1mA I 25mA VCC V Current Limit I V = 4.3V, V = 6V 26.5 54 100 mA CC VCC-MAX CC IN V Dropout V V = 4.5V, I = 20mA 4.2 V CC CC-DO IN VCC V V rising 4.05 4.2 4.3 CC UVR CC V UVLO V CC V V falling 3.65 3.8 3.9 CC UVF CC Maxim Integrated 2 www.maximintegrated.com