EVALUATION KIT AVAILABLE MAX5974E/MAX5974F Current-Mode PWM Controllers for Low-Cost Flyback Supplies General Description Features The MAX5974E/MAX5974F provide control for wide- S Peak Current-Mode Control, Synchronous Flyback input-voltage, current-mode PWM, nonisolated, synchro- PWM Controller nous flyback converters in Power-over-Ethernet (PoE) S Synchronous MOSFET Driver Output powered device (PD) applications. The MAX5974E is S Internal 1% Error Amplifier Eliminates Shunt well-suited for universal or telecom input range, while the Regulator and Optocoupler MAX5974F also accommodates low input voltage down to 8.4V. S 100kHz to 600kHz Programmable Q8% Switching Frequency, Synchronization Up to 1.2MHz The devices include several features to enhance supply efficiency, including a synchronous MOSFET driver out- S Programmable Frequency Dithering for Low-EMI, put. The AUX driver drives an output synchronous rectifier Spread-Spectrum Operation to lower conduction losses. Programmable dead time S Programmable Dead Time, PWM Soft-Start, between the AUX and main driver allows for zero-voltage Current Slope Compensation switching (ZVS). Under light-load conditions, the devices reduce the switching frequency (frequency foldback) to S Programmable Feed-Forward Maximum Duty- reduce switching losses. Cycle Clamp, 80% Maximum Limit An internal error amplifier with a 1% reference eliminates S Frequency Foldback for High-Efficiency Light- the need for an external shunt regulator and optocoupler. Load Operation The programmable frequency dithering feature provides S Internal Bootstrap UVLO with Large Hysteresis low-EMI, spread-spectrum operation. S 100A (typ) Startup Supply Current The MAX5974E/MAX5974F are available in 16-pin S Fast Cycle-by-Cycle Peak Current-Limit, 35ns TQFN-EP packages and are rated for operation over the Typical Propagation Delay -40C to +85C temperature range. S 115ns Current-Sense Internal Leading-Edge Applications Blanking PoE IEEE 802.3af/at Powered Devices S Output Short-Circuit Protection with Hiccup Mode High-Power PD (Beyond the 802.3af/at Standard) S Internal 18V Zero Clamp on Supply Input IP Phones S 3mm x 3mm, Lead-Free, 16-Pin TQFN-EP Wireless Access Nodes Security Cameras Ordering Information PART TEMP RANGE PIN-PACKAGE UVLO THRESHOLD (V) TOP MARK MAX5974EETE+ -40C to +85C 16 TQFN-EP* 16 +AIR MAX5974FETE+ -40C to +85C 16 TQFN-EP* 8.4 +AIS +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. IEEE is a registered service mark of the Institute of Electrical and Electronics Engineers, Inc. For pricing, delivery, and ordering information, please contact Maxim Direct 19-5804 Rev 2 10/13 at 1-888-629-4642, or visit Maxims website at www.maximintegrated.com.MAX5974E/MAX5974F Current-Mode PWM Controllers for Low-Cost Flyback Supplies ABSOLUTE MAXIMUM RATINGS IN to GND (V = 0V) ...........................................-0.3V to +26V Continuous Power Dissipation (T = +70NC) EN A 16-Pin TQFN (derate 20.8mW/NC above +70NC) .......1666mW EN, NDRV, AUXDRV to GND .....................-0.3V to (V + 0.3V) IN RT, DT, FFB, COMP, SS, DCLMP, DITHER/SYNC Operating Temperature Range .......................... -40NC to +85NC Maximum Junction Temperature .....................................+150NC to GND .................................................................-0.3V to +6V FB to GND (MAX5974E only) .....................................-6V to +6V Storage Temperature Range ............................ -65NC to +150NC Lead Temperature (soldering, 10s) ................................+300NC FB to GND (MAX5974F only) ..................................-0.3V to +6V CS, CSSC to GND ...................................................-0.8V to +6V Soldering Temperature (reflow) ......................................+260NC PGND to GND ......................................................-0.3V to +0.3V Maximum Input/Output Current (continuous) NDRV, AUXDRV ............................................................100mA NDRV, AUXDRV (pulsed for less than 100ns) ..................Q1A 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 1) TQFN Junction-to-Ambient Thermal Resistance ( ) ..........48C/W JA Junction-to-Case Thermal Resistance (JC) .................7C/W Note 1: 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 = 12V (for MAX5974E, bring V up to 17V for startup), V = V = V = V = V = V = V , V = IN IN CS CSSC DITHER/SYNC FB FFB DCLMP GND EN +2V, NDRV = AUXDRV = SS = COMP = unconnected, R = 34.8kI, R = 25kI, C = 1FF, T = -40NC to +85NC, unless otherwise RT DT IN A noted. Typical values are at T = +25NC.) (Note 2) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS UNDERVOLTAGE LOCKOUT/STARTUP (IN) MAX5974E 15.4 16 16.5 Bootstrap UVLO Wakeup Level V V rising V INUVR IN MAX5974F 8 8.4 8.85 Bootstrap UVLO Shutdown V V falling 6.65 7 7.35 V INUVF IN Level IN Clamp Voltage V I = 2mA (sinking) 17 18.5 20 V IN CLAMP IN V = +15V (for MAX5974E) IN IN Supply Current in I V = +7.5V (for MAX5974F), 100 150 FA START IN Undervoltage Lockout when in bootstrap UVLO IN Supply Current After Startup I V = +12V 1.8 3 mA C IN ENABLE (EN) V V rising 1.17 1.215 1.26 ENR EN Enable Threshold V V V falling 1.09 1.14 1.19 ENF EN Input Current I 1 FA EN OSCILLATOR (RT) RT Bias Voltage V 1.23 V RT NDRV Switching Frequency f 100 600 kHz SW Range 2 Maxim Integrated