EVALUATION KIT AVAILABLE MAX5991A/MAX5991B IEEE 02.af-Compliant High-Efficiency Class 1Class 2 Powered Devices with Integrated DC-DC Converter General Description Benefits and Features The MAX5991A/MAX5991B provide a complete power- High Integration Saves Space and BOM Cost supply solution as IEEE 802.3af-compliant Class 1/ Efficient, Integrated DC-DC Converter (with Class 2 Powered Devices (PDs) in a Power-over-Ethernet Integrated Switches) Built-In Output-Voltage Monitoring (PoE) system. The devices integrate the PD interface with an efficient DC-DC converter, offering a low external part Protects Against Overload, Output Short Circuit, Output Overvoltage, and Overtemperature count PD solution. The devices also include a low-drop- out regulator, MPS, sleep, and ultra-low power modes. Integrated TVS Diode Withstands Cable Discharge Event (CDE) The PD interface provides a detection signature and Internal LDO Regulator with Up to 100mA Load a Class 1/Class 2 classification signature with a single external resistor. The PD interface also provides an isola- IEEE 802.3af-Compliant Features Reduce Design Time PoE Class 1/Class 2 Classification Set with Single tion power MOSFET, a 60mA (max) inrush current limit, Resistor and a 321mA (typ) operating current limit. Intelligent Maintain Power Signature (MPS) The integrated step-down DC-DC converter uses a peak Complies with IEEE 802.3af Specification current-mode control scheme and provides an easy-to- Simplified Wall Adapter Interface implement architecture with a fast transient response. Pass 2kV, 200m CAT-6 Cable Discharge Event The step-down converter operates in a wide input volt- High Efficiency During Light Loads Reduces Power age range from 8.7V to 60V and supports up to 6.49W of Consumption input power at 1.3A load. The DC-DC converter operates Sleep and Ultra-Low-Power Mode at a fixed 430kHz switching frequency, with an efficiency- Frequency Foldback for High-Efficiency Light- boosting frequency foldback that reduces the switching Load Operation frequency by half at light loads. Back-Bias Capability to Optimize the Efficiency The devices feature an input undervoltage-lockout Robust Performance (UVLO) with wide hysteresis and long deglitch time 8.7V to 60V Wide Input Voltage Range to compensate for twisted-pair cable resistive drop Hiccup-Mode Runaway Current Limit and to assure glitch-free transition during power-on/-off 49mA (typ) Inrush Current Limit conditions. The devices also feature overtemperature Open-Drain RESET Output shutdown, short-circuit protection, output overvolt- age protection, and hiccup current limit for enhanced Easy to Design With performance and reliability. 3.2V to 14V Programmable Output Voltage Range Internal Compensation All devices are available in a 20-pin, 4mm x 4mm, TQFN Fixed 430kHz Switching Frequency power package and operate over the -40C to +85C temperature range. Ordering Information appears at end of data sheet. Applications IEEE 802.3af-Powered Devices IP Phones Wireless Access Nodes IP Security Cameras WiMAX Base Stations IEEE is a registered service mark of the Institute of Electrical and Electronics Engineers, Inc. WiMAX is a registered certification mark and registered service mark of WiMAX Forum. 19-6529 Rev 2 1/15MAX5991A/MAX5991B IEEE 802.3af-Compliant, High-Efficiency, Class 1/Class 2, Powered Devices with Integrated DC-DC Converter Absolute Maximum Ratings (All voltages referenced to GND, unless otherwise noted.) VDRV to V ............................................ -0.3V to (V + 0.3V) DD DD PGND to GND ......................................................-0.3V to +0.3V V to GND ...........................................................-0.3V to +70V DD LX Total RMS Current ...........................................................1.6A (100V, 100ms, R = 3.3k) (Note 1) TEST Continuous Power Dissipation (T = + 70NC) V , WAD, RREF to GND ........................ -0.3V to (V + 0.3V) A CC DD TQFN (derate 28.6mW/NC above +70NC)...............2285.7mW AUX, LDO IN, LED to GND .................................... -0.3V to 16V Operating Temperature Range .......................... -40NC to +85NC LDO OUT to GND .............................. -0.3V to (LDO IN + 0.3V) Junction Temperature .....................................................+150NC LDO FB to GND ......................................................-0.3V to +6V Storage Temperature Range ............................ -65NC to +150NC LX to GND ................................................ -0.3V to (V + 0.3V) CC Lead Temperature (soldering, 10s) ................................+300NC LDO OUT, VDRV, FB, RESET, WK, Soldering Temperature (reflow) ......................................+260NC SL, ULP, MPS, CLASS2 to GND .........................-0.3V to +6V Note 1: See Figure 1, Test Circuit. 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. (Note 2) Package Thermal Characteristics Junction-to-Ambient Thermal Resistance (q ) ..............35C/W JA Junction-to-Case Thermal Resistance (q ) ..................2.7C/W JC 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 = 48V, R = 24.9k, LED, V , SL, ULP, WK, RESET, LDO OUT unconnected, WAD = LDO EN = LDO IN = PGND = GND, DD SIG CC C1 = 68nF, C2 = 10F, C3 = 1F (see Figure 3), V = V = 0V, LX unconnected, CLASS2 = 0V, MPS = 0V. All voltages are refer- FB AUX enced to GND, unless otherwise noted. 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 POWER DEVICE (PD) INTERFACE DETECTION MODE Input Offset Current I V = 1.4V to 10.1V (Note 4) 8 FA OFFSET VDD Effective Differential Input V = 1.4V to 10.1V with 1V step, VDD dR 23.95 25.5 kI Resistance (Note 5) CLASSIFICATION MODE Classification Enable Threshold V V rising 10.2 11.42 12.5 V TH,CLS,EN DD Classification Disable Threshold V V rising 22 23 23.8 V TH,CLS,DIS DD Classification Stability Time 2 ms CLASS2 = GND 9.12 10.5 11.88 V = 12.6V to DD Classification Current I mA CLASS 20V CLASS2 = VDRV 16.1 18 20.9 POWER MODE V Supply Voltage Range V 60 V DD DD V Supply Current I V = 60V 4.8 6.6 mA DD DD DD V Turn-On Voltage V V rising 37.2 38.7 40 V DD ON DD V Turn-Off Voltage V V falling 30 31.4 V DD OFF DD Maxim Integrated 2 www.maximintegrated.com