MAX17681 4.5V to 42V Input, High-Efficiency, Iso-Buck DC-DC Converter General Description Benefits and Features The MAX17681/MAX17681A is a high-voltage, high- Reduces External Components and Total Cost efficiency, iso-buck DC-DC converter designed to provide No Optocoupler isolated power up to 5W. The device operates over a Synchronous Primary Operation wide 4.5V to 42V input and uses primary-side feedback All-Ceramic Capacitors, Compact Layout to regulate the output voltage. Reduces Number of DC-DC Regulators to Stock The MAX17681/MAX17681A uses peak-current-mode Wide 4.5V to 42V Input control. The low-resistance, on-chip MOSFETs ensure 0.9V to 0.96 x V Primary Output Voltage IN high efficiency at full load while simplifying the PCB layout. Delivers Up to 5W Output Power The MAX17681/MAX17681A devices generate a well Reduces Power Dissipation regulated primary side voltage which is then scaled by a Peak Efficiency > 90% suitable transformer turns ratio to derive isolated secondary 0.9A (typ) Shutdown Current output rails. While both MAX17681 and MAX17681A Operates Reliably in Adverse Industrial Environments support primary side overcurrent protection, the Peak and Sink Current-Limit Protection MAX17681A is an enhanced design that supports robust 1.7% Feedback Accuracy secondary-side overcurrent protection as well. Programmable EN/UVLO Threshold The MAX17681/MAX17681A is available in a compact Adjustable Soft-Start 10-pin (3mm x 2mm) TDFN package. Simulation models Overtemperature Protection are available. -40C to +125C Operation Short-Circuit Protection Applications MAX17681A Supports Robust Secondary-Side Isolated Fieldbus Interfaces Short-Circuit Protection PLC I/O Modules MAX17681A Is Recommended for All New Designs Smart Meters Isolated Power Supplies in Medical Equipment Ordering Information appears at end of data sheet. Floating Power Supply Generation Application Circuit T1 V OUT D1 1:2.4 24V, 100mA VIN VIN LX 17V TO 32V C1 R4 1F EN/UVLO PGND C7 49.9 NPRI NSEC 2.2F Z1 V CC GND C3 1F MAX17681 MAX17681A C2 R1 10uF 105k SS C4 FB 33nF R2 10k C8 1nF COMP RESET R3 4.75k C6 680pF C5 33nF 19-7053 Rev 4 3/18MAX17681 4.5V to 42V Input, High-Efficiency, Iso-Buck DC-DC Converter Absolute Maximum Ratings V to GND ............................................................-0.3V to +48V Output Short-Circuit Duration ....................................Continuous IN EN/UVLO to GND...................................... -0.3V to (V + 0.3V) Operating Temperature Range ......................... -40C to +125C IN LX to PGND............................................... -0.3V to (V + 0.3V) Junction Temperature ......................................................+150C IN V , FB, RESET, COMP, SS to GND ....................-0.3V to +6V Storage Temperature Range ............................ -65C to +160C CC PGND to GND ......................................................-0.3V to +0.3V Lead Temperature (soldering, 10s) .................................+300C LX Total RMS Current ........................................................1.6A Soldering Temperature (reflow) .......................................+260C 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 TYPE: 10 TDFN Package Code T1032N+1 Outline Number 21-0429 Land Pattern Number 90-0082 THERMAL RESISTANCE, FOUR-LAYER BOARD (N ote 1) Junction to Ambient ( ) 67.3C/W JA Junction to Case ( ) 18.2C/W JC For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a +, , or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. 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. Note 1: Continuous Power Dissipation (T = +70C) (derate 14.9mW/C above +70C) (multilayer board) 1188.7mW A Maxim Integrated 2 www.maximintegrated.com