EVALUATION KIT AVAILABLE MAX17245 3.5V36V, 3.5A, Synchronous Buck Converter With 28A Quiescent Current and Reduced EMI General Description Benefits and Features The MAX17245 high-efficiency, synchronous step-down Eliminates External Components and Reduces DC-DC converter with integrated MOSFETs operates Total Cost over a 3.5V to 36V input voltage range with 42V input Integrated High-Side and Low-Side Switch Enables transient protection. The MAX17245 can operate in drop- Synchronous Operation for High Efficiency and out condition by running at 98% duty cycle. This converter Reduced Cost All-Ceramic Capacitor Solution Allows delivers up to 3.5A and generates fixed output voltages of 3.3V/5V, along with the ability to program the output voltage Ultra-Compact Solution Size 220kHz to 2.2MHz Adjustable Frequency with between 1V to 10V. External Synchronization The MAX17245 uses a current-mode control architecture Power Good Output and High-Voltage EN Input and can operate in the pulse-width modulation (PWM) Simplify Power Sequencing or pulse-frequency modulation (PFM) control schemes. Increases Design Flexibility PWM operation provides constant frequency operation at 180 Out-of-Phase Clock Output at SYNCOUT all loads and is useful in applications sensitive to switching Enables Cascaded Power Supplies for Increased frequency. PFM operation disables negative inductor Power Output current and additionally skips pulses at light loads for Fixed Output Voltage with 2% Accuracy (5V/3.3V) high efficiency. Under light-load applications, the external or Externally Resistor Adjustable (1V to 10V) sync pin FSYNC logic input allows the device to operate in either PFM mode for reduced current consumption or Reduces Power Dissipation fixed-frequency PWM (forced-PWM) mode to eliminate >90% Peak Efficiency frequency variation to minimize EMI. Fixed-frequency PWM and PFM Operation Optimizes Conversion PWM mode is extremely useful for power supplies Efficiency From Heavy to Light Loads designed for RF transceivers where tight emission control Automatic LX Slew-Rate Adjustment for Optimum is necessary. Efficiency Across Operating Frequency Range Low 5A (typ.) Shutdown Current This device is available in a compact 16-pin (5mm x 5mm) Low 28A (typ.) Quiescent Current TQFN package with exposed pad and 16-pin TSSOP. -40C to +85C operation. Operates Reliably 42V Input Voltage Transient Protection Typical Application Circuit Fixed 8ms Internal Software Start Reduces Input Inrush Current V BAT Cycle-by-Cycle Current limit, Thermal Shutdown C IN2 CIN3 C IN1 with Automatic Recovery R 4.7F 4.7F 0I C Reduced EMI Emission with Spread-Spectrum BST SUP SUPSW 0.1F Control L1 BST VOUT EN 2.2H 5V AT 3.5A LX OSC SYNC PULSE FSYNC V D1 C OUT OUT Applications V BIAS 22F R SNUB* OUT COMP C SNUB* Distributed Supply Regulation CCOMP1 FB R MAX17245 FOSC 1000pF CCOMP2 12kI Wall Transformer Regulation VOUT VBIAS R 12pF COMP FOSC 20kI General-Purpose Point-of-Load R R SYNCOUT PGOOD 100I 10kI BIAS PGOOD POWER-GOOD OUTPUT C BIAS SYNCOUT 180 OUT-OF-PHASE OUTPUT 1F PGND AGND *R = 1I and C = 220pF required for SNUB SNUB the following operating conditions: Ordering Information/Selector Guide appears at end of data V R 25V, V P 5V, f R 1.8MHz, BAT OUT SW FPWM mode enabled sheet. 19-8527 Rev 0 4/16MAX17245 3.5V36V, 3.5A, Synchronous Buck Converter With 28A Quiescent Current and Reduced EMI Absolute Maximum Ratings SUP, SUPSW, EN to PGND ..................................-0.3V to +42V Output Short-Circuit Duration ....................................Continuous LX (Note 1) ............................................................-0.3V to +42V Continuous Power Dissipation (T = +70C)* A SUP to SUPSW ....................................................-0.3V to +0.3V TQFN (derate 28.6mW/C above +70C) ...............2285.7mW BIAS to AGND .........................................................-0.3V to +6V TSSOP (derate 26.1mW/C above +70C) ............2088.8mW SYNCOUT, FOSC, COMP, FSYNC, Operating Temperature Range ....................... -40C to +85C PGOOD, FB to AGND ........................-0.3V to (V + 0.3V) Junction Temperature ......................................................+150C BIAS OUT to PGND .......................................................-0.3V to +12V Storage Temperature Range ............................ -65C to +150C BST to LX (Note 1) ..................................................-0.3V to +6V Lead Temperature (soldering, 10s) .................................+300C AGND to PGND................................................... -0.3V to + 0.3V Soldering Temperature (reflow) .......................................+260C LX Continuous RMS Current ................................................3.5A *As per JEDEC51 standard (multilayer board). 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 Thermal Characteristics (Note 2) TQFN TSSOP Junction-to-Ambient Thermal Resistance (B )...........35C/W Junction-to-Ambient Thermal Resistance (B )........38.3C/W JA JA Junction-to-Case Thermal Resistance (B ) ..............2.7C/W Junction-to-Case Thermal Resistance (B ) .................3C/W JC JC Note 1: Self-protected against transient voltages exceeding these limits for 50ns under normal operation and loads up to the maximum rated output current. Note 2: 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 = 14V, V = 14V, L1 = 2.2H, C = 4.7F, C = 22F, C = 1F, C = 0.1F, R = 12k, SUP SUPSW EN IN OUT BIAS BST FOSC T = T = -40C to +85C, unless otherwise noted. Typical values are at T = +25C.) (Note 3) A J A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage V , V 3.5 36 V SUP SUPSW Line Transient Event V t < 1s 42 V SUP t LT t LT Supply Voltage Standby mode, no load, V = 5V, OUT 28 40 V = 0V FSYNC Supply Current I A SUP STANDBY Standby mode, no load, V = 3.3V, OUT 22 35 V = 0V FSYNC Shutdown Supply Current I V = 0V 5 10 A SHDN EN V = V = 6V to 42V, SUP SUPSW BIAS Regulator Voltage V 4.7 5 5.4 V BIAS I = 0 to 10mA BIAS BIAS Undervoltage Lockout V V rising 2.95 3.15 3.40 V UVBIAS BIAS BIAS Undervoltage Lockout 450 650 mV Hysteresis Thermal Shutdown Threshold +175 C Thermal Shutdown Threshold 15 C Hysteresis Maxim Integrated 2 www.maximintegrated.com