MAX5942A/MAX5942B 19-3024 Rev 2 9/04 IEEE 802.3af Power-Over-Ethernet Interface/PWM Controller for Power Devices General Description Features The MAX5942A/MAX5942B integrate a complete power Powered Device Interface IC for powered devices (PD) in a power-over-ethernet Fully Integrated IEEE 802.3af-Compliant PD (PoE) system. The MAX5942A/MAX5942B provide a PD Interface interface and a compact DC-DC PWM controller suitable PD Detection and Programmable Classification for flyback and forward converters in either isolated or Signatures nonisolated designs. Less than 10A Leakage Current Offset During The MAX5942A/MAX5942B PD interface complies with Detection the IEEE 802.3af standard, providing the PD with a Integrated MOSFET for Isolation and Inrush detection signature, a classification signature, and an Current Limiting integrated isolation switch with programmable inrush cur- Gate Output Allows External Control of the rent control. These devices also feature power-mode Internal Isolation FET undervoltage lockout (UVLO) with wide hysteresis and Programmable Inrush Current Control/ULVO power-good status outputs. PGOOD/PGOOD Outputs Enable PWM The MAX5942A/MAX5942B also integrate all the build- Controller ing blocks necessary for implementing DC-DC fixed- PWM Controller frequency isolated power supplies. This device is a Wide Input Range: 18V to 67V current-mode controller with an integrated high startup Isolated (Without Optocoupler) or Nonisolated circuit suitable for isolated telecom/industrial voltage Power Supply range power supplies. A high-voltage startup circuit Current-Mode Control allows the PWM controller to draw power directly from the Leading-Edge Blanking 18V to 67V input supply during startup. The switching Internally Trimmed 275kHz 10% Oscillator frequency is internally trimmed to 275kHz 10%, thus reducing magnetics and filter components. The Soft-Start MAX5942A allows an 85% operating duty cycle and can Ordering Information be used to implement flyback converters. The MAX5942B limits the operating duty cycle to less than 50% and can PIN- M A X DU T Y be used in single-ended forward converters. The PART TEMP RANGE PACKAGE C YCL E (% ) MAX5942A/MAX5942B are designed to work with or with- out an external diode bridge in front of the PD. MAX5942AESE* -40C to +85C 16 SO 85 The MAX5942A/MAX5942B are available in 16-pin SO MAX5942ACSE 0C to +70C 16 SO 85 packages. MAX5942BESE* -40C to +85C 16 SO 50 Applications MAX5942BCSE 0C to +70C 16 SO 50 *Future productcontact factory for availability. IP Phones Wireless Access Nodes Pin Configuration Internet Appliances Computer Telephony TOP VIEW Security Cameras V+ 1 16 V CC Power Devices in Power-Over-Ethernet/ V 2 15 NDRV DD Power-Over-MDI FB 3 14 V- SS SHDN 4 MAX5942A 13 CS MAX5942B ULVO 5 12 GND RCL 6 11 PGOOD Typical Operating Circuit appears at end of data sheet. GATE 7 10 PGOOD V 8 9 OUT EE IEEE is a trademark of the Institute of Electrical and Electronics SO Engineers. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim s website at www.maxim-ic.com.IEEE 802.3af Power-Over-Ethernet Interface/PWM Controller for Power Devices ABSOLUTE MAXIMUM RATINGS (All voltages are referenced to V , unless otherwise noted.) UVLO, PGOOD, PGOOD to V .....................................20mA EE EE GND........................................................................-0.3V to +90V GATE to V ....................................................................80mA EE OUT, PGOOD ...........................................-0.3V to (GND + 0.3V) V , V .........................................................................20mA DD CC RCL, GATE .............................................................-0.3V to +12V NDRV Continuous ...........................................................25mA UVLO........................................................................-0.3V to +8V NDRV (pulsed for less than 1s) .......................................1A PGOOD to OUT.........................................-0.3V to (GND + 0.3V) Continuous Power Dissipation (T = +70C) A V+ to V-...................................................................-0.3V to +80V 16-Pin SO (derate 9.1mW/C above +70C)................727mW V to V-.................................................................-0.3V to +40V Operating Temperature Ranges DD V to V-..............................................................-0.3V to +12.5V CC MAX5942 CSE...................................................0C to +70C FB, NDRV, SS SHDN, CS to V-..................-0.3V to (V + 0.3V) MAX5942 ESE................................................-40C to +85C CC Maximum Input/Output Current (continuous) Storage Temperature Range .............................-65C to +150C OUT to V ...................................................................500mA EE Junction Temperature......................................................+150C GND, RCL to V ............................................................70mA Lead Temperature (soldering, 10s) ................................+300C EE 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. ELECTRICAL CHARACTERISTICS (V = (GND - V ) = 48V, GATE = PGOOD = PGOOD = OPEN, V- tied to OUT, V+ tied to GND, UVLO = V , T = T to T , IN EE EE A MIN MAX unless otherwise noted. Typical values are at T = +25C. All voltages are referenced to V , unless otherwise noted.) (Note 1) A EE PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS PD INTERFACE DETECTION MODE Input Offset Current I V = 1.4V to 10.1V (Note 2) 10 A OFFSET IN Effective Differential Input V = 1.4V up to 10.1V with 1V step, IN dR 550 k Resistance OUT = PGOOD = GND (Note 3) CLASSIFICATION MODE Classification Current Turn-Off V V rising (Note 4) 20.8 21.8 22.5 V TH,CLSS IN Threshold Class 0, R = 10k 02 CL V = 12.6V IN Class 1, R = 732 9.17 11.83 CL to 20V, R DISC Classification Current I Class 2, R = 392 17.29 19.71 mA CLASS CL = 25.5k Class 3, R = 255 26.45 29.55 CL (Notes 5, 6) Class 4, R = 178 36.6 41.4 CL POWER MODE Operating Supply Voltage V V = (GND - V)67V IN IN EE Operating Supply Current I Measure at GND, not including R 0.4 1mA IN DISC Default Power Turn-On Voltage V V increasing, UVLO = V 37.4 38.6 40.1 V UVLO,ON IN EE Default Power Turn-Off Voltage V V decreasing, UVLO = V 30 V UVLO,OFF IN EE Default Power Turn-On/Off V 7.4 V HYST,UVLO Hysteresis External UVLO Programming V Set UVLO externally (Note 7) 12 67 V IN,EX Range UVLO External Reference Voltage V V increasing 2.400 2.460 2.522 V REF,UVLO UVLO UVLO External Reference HYST Ratio to V 19.2 20 20.9 % REF,UVLO Voltage Hysteresis 2 MAX5942A/MAX5942B