EVALUATION KIT AVAILABLE MAX16935/MAX16939 36V, 3.5A, 2.2MHz Step-Down Converters with 28A Quiescent Current General Description Benefits and Features The MAX16935/MAX16939 are 3.5A current-mode step- Integration and High-Switching Frequency Saves down converters with integrated high-side and low- Space side MOSFETs designed to operate with an external Integrated 3.5A High-Side Switch Schottky diode for better efficiency. The low-side MOSFET Low-BOM-Count Current-Mode Control enables fixed-frequency forced-PWM (FPWM) operation Architecture under light-load applications. The devices operate with Fixed Output Voltage with 2% Accuracy or input voltages from 3.5V to 36V, while using only 28FA Externally Resistor Adjustable (1V to 10V) quiescent current at no load. The switching frequency is 220kHz to 2.2MHz Switching Frequency with resistor programmable from 220kHz to 2.2MHz and can Three Operation Modes (Skip Mode, Forced be synchronized to an external clock. The devices output Fixed-Frequency Operation, and External voltage is available as 3.3V/5V fixed or adjustable from Frequency Synchronization) 1V to 10V. The wide input voltage range along with its Automatic LX Slew-Rate Adjustment for Optimum ability to operate at 98% duty cycle during undervoltage Efficiency Across Operating Frequency Range transients make the devices ideal for automotive and 180 Out-of-Phase Clock Output at SYNCOUT industrial applications. Enables Cascaded Power Supplies for Increased Under light-load applications, the FSYNC logic input Power Output allows the devices to either operate in skip mode for Spread-Spectrum Frequency Modulation Reduces reduced current consumption or fixed-frequency FPWM EMI Emissions mode to eliminate frequency variation to minimize EMI. Fixed-frequency FPWM mode is extremely use- Wide Input Voltage Range Supports Automotive ful for power supplies designed for RF transceivers Applications where tight emission control is necessary. Protection 3.5V to 36V Input Voltage Range (42V Tolerant) features include cycle-by-cycle current limit and thermal Enable Input Compatible from 3.3V Logic Level shutdown with automatic recovery. Additional features to 42V include a power-good monitor to ease power-supply Robust Performance Supports Wide Range of sequencing and a 180N out-of-phase clock output relative Automotive Applications to the internal oscillator at SYNCOUT to create cascaded power supplies with multiple devices. -40C to +125C Automotive Temperature Range Thermal-Shutdown Protection The MAX16935/MAX16939 operate over the -40NC AEC-Q100 Qualified to +125NC automotive temperature range and are available in 16-pin (5mm x 5mm) TQFN-EP and 16-pin Power-Good Output Allows Power-Supply TSSOP-EP packages. Sequencing Tight Overvoltage Protection Provides Smaller Applications Overshoot Voltages (MAX16939) Point-of-Load Applications Distributed DC Power Systems Ordering Information/Selector Guide and Typical Navigation and Radio Head Units Application Circuit appear at end of data sheet. 19-6868 Rev 17 1/18MAX16935/MAX16939 36V, 3.5A, 2.2MHz Step-Down Converters with 28A Quiescent Current 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 = +70NC)* A SUP to SUPSW .....................................................-0.3V to +0.3V TQFN (derate 28.6mW/NC above +70NC)...............2285.7mW BIAS to AGND .........................................................-0.3V to +6V TSSOP (derate 26.1mW/NC above +70NC).............2088.8mW SYNCOUT, FOSC, COMP, FSYNC, Operating Temperature Range .................... -40NC to +125NC PGOOD, FB to AGND ........................-0.3V to (V + 0.3V) Junction Temperature .....................................................+150NC BIAS OUT to PGND ........................................................-0.3V to +12V Storage Temperature Range ............................ -65NC to +150NC BST to LX (Note 1) ..................................................-0.3V to +6V Lead Temperature (soldering, 10s) ................................+300NC AGND to PGND ...................................................-0.3V to + 0.3V Soldering Temperature (reflow) ......................................+260NC 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 opera- tion 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 ) ..........35NC/W Junction-to-Ambient Thermal Resistance (B ) .......38.3NC/W JA JA Junction-to-Case Thermal Resistance (B ) ..............2.7NC/W Junction-to-Case Thermal Resistance (B ) .................3NC/W JC JC Note 1: Self-protected against transient voltages exceeding these limits for 50ns under normal operation and loads up to the maxi- mum 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 = 2.2FH, C = 4.7FF, C = 22FF, C = 1FF, C = 0.1FF, R = 12kI, SUP SUPSW EN IN OUT BIAS BST FOSC T = T = -40NC to +125NC, unless otherwise noted. Typical values are at T = +25NC.) A J A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage V V 3.5 36 V SUP, SUPSW Load-Dump Event Supply V t < 1s 42 V SUP LD LD Voltage Standby mode, no MAX16935/39 28 40 load, V = 5V, OUT MAX16935C 32 45 V = 0V FSYNC Supply Current I FA SUP STANDBY Standby mode, no MAX16935/39 22 35 load, V = 3.3V, OUT MAX16935C 23 36 V = 0V FSYNC Shutdown Supply Current I V = 0V 5 10 FA 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 NC Thermal-Shutdown Threshold 15 NC Hysteresis Maxim Integrated 2 www.maximintegrated.com