EVALUATION KIT AVAILABLE MAX5974A/MAX5974B/MAX5974C/MAX5974D Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers General Description Features S Peak Current-Mode Control, Active-Clamped The MAX5974 provide control for wide-input-voltage, Forward PWM Controller active-clamped, current-mode PWM, forward converters in Power-over-Ethernet (PoE) powered device (PD) appli- S Regulation Without Optocoupler (MAX5974A/ cations. The MAX5974A/MAX5974C are well-suited for MAX5974B) universal or telecom input range, while the MAX5974B/ S Internal 1% Error Amplifier MAX5974D also accommodate low input voltage down S 100kHz to 600kHz Programmable Q8% Switching to 10.5V. Frequency, Synchronization Up to 1.2MHz The devices include several features to enhance sup- S Programmable Frequency Dithering for Low-EMI, ply efficiency. The AUX driver recycles magnetizing Spread-Spectrum Operation current instead of wasting it in a dissipative clamp circuit. S Programmable Dead Time, PWM Soft-Start, Programmable dead time between the AUX and main Current Slope Compensation driver allows for zero-voltage switching (ZVS). Under S Programmable Feed-Forward Maximum Duty- light-load conditions, the devices reduce the switching Cycle Clamp, 80% Maximum Limit frequency (frequency foldback) to reduce switching S Frequency Foldback for High-Efficiency Light- losses. Load Operation The MAX5974A/MAX5974B feature unique circuitry to S Internal Bootstrap UVLO with Large Hysteresis achieve output regulation without using an optocoupler, S 100A (typ) Startup Supply Current while the MAX5974C/MAX5974D utilize the traditional S Fast Cycle-by-Cycle Peak Current-Limit, 35ns optocoupler feedback method. An internal error amplifier Typical Propagation Delay with a 1% reference is very useful in nonisolated design, eliminating the need for an external shunt regulator. S 115ns Current-Sense Internal Leading-Edge Blanking The devices feature a unique feed-forward maximum S Output Short-Circuit Protection with Hiccup Mode duty-cycle clamp that makes the maximum clamp voltage during transient conditions independent of the S Reverse Current Limit to Prevent Transformer line voltage, allowing the use of a power MOSFET with Saturation Due to Reverse Current lower breakdown voltage. The programmable frequency S Internal 18V Zener Clamp on Supply Input dithering feature provides low-EMI, spread-spectrum S 3mm x 3mm, Lead-Free, 16-Pin TQFN-EP operation. The MAX5974 are available in 16-pin TQFN-EP Applications packages and are rated for operation over the -40C to PoE IEEE 802.3af/at Powered Devices +85C temperature range. High-Power PD (Beyond the 802.3af/at Standard) Active-Clamped Forward DC-DC Converters IP Phones IEEE is a registered service mark of the Institute of Electrical Wireless Access Nodes and Electronics Engineers, Inc. Security Cameras Ordering Information/Selector Guide UVLO PART TOP MARK PIN-PACKAGE TEMP RANGE FEEDBACK MODE THRESHOLD (V) MAX5974AETE+ +AHY 16 TQFN-EP* -40C to +85C 16 Sample/Hold MAX5974BETE+ +AHZ 16 TQFN-EP* -40C to +85C 8.4 Sample/Hold MAX5974CETE+ +AIA 16 TQFN-EP* -40C to +85C 16 Continuously Connected MAX5974DETE+ +AIB 16 TQFN-EP* -40C to +85C 8.4 Continuously Connected MAX5974DATE+ +AIB 16 TQFN-EP* -40C to +125C 8.4 Continuously Connected +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. For pricing, delivery, and ordering information, please contact Maxim Direct 19-5331 Rev 5 7/15 at 1-888-629-4642, or visit Maxims website at www.maximintegrated.com.MAX5974A/MAX5974B/MAX5974C/MAX5974D Active-Clamped, Spread-Spectrum, Current-Mode PWM Controllers ABSOLUTE MAXIMUM RATINGS IN to GND (V = 0V) ...........................................-0.3V to +26V Maximum Input/Output Current (continuous) EN EN .....................................................................................1mA NDRV, AUXDRV to GND ............................-0.3V to (V + 0.3V) IN RT, DT, FFB, COMP, SS, DCLMP, DITHER/SYNC NDRV, AUXDRV (pulsed for less than 100ns) ..................Q1A to GND .................................................................-0.3V to +6V Continuous Power Dissipation (T = +70NC) (Note 1) A FB to GND (MAX5974A/MAX5974B only) ..................-6V to +6V 16-Pin TQFN (derate 20.8mW/NC above +70NC) .......1666mW FB to GND (MAX5974C/MAX5974D only) ..............-0.3V to +6V Operating Temperature Range .......................... -40NC to +85NC CS, CSSC to GND ...................................................-0.8V to +6V Maximum Junction Temperature .....................................+150NC PGND to GND ......................................................-0.3V to +0.3V Storage Temperature Range ............................ -65NC to +150NC Lead Temperature (soldering, 10s) ................................+300NC Soldering Temperature (reflow) ......................................+260NC 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) Junction-to-Ambient Thermal Resistance (B ) ..............48NC/W JA Junction-to-Case Thermal Resistance (B ) .....................7NC/W JC 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 MAX5974A/MAX5974C, bring V up to 17V for startup), V = V = V = V = V = V = IN IN CS CSSC DITHER/SYNC FB FFB DCLMP V , V = +2V, NDRV = AUXDRV = SS = COMP = unconnected, R = 34.8kI, R = 25kI, C = 1FF, T = -40NC to +85NC, GND EN RT DT IN A unless otherwise noted. Typical values are at T = +25NC.) (Note 2) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS UNDERVOLTAGE LOCKOUT/STARTUP (IN) MAX5974A/C 15.4 16 16.5 -40C to 8 8.4 8.85 +85C Bootstrap UVLO Wakeup Level V V rising V INUVR IN MAX5974B/D -40C to 7.95 8.4 8.85 +125C -40C to +85C 6.65 7 7.35 Bootstrap UVLO Shutdown V V falling V INUVF IN Level -40C to +125C 6.6 7 7.35 IN Clamp Voltage V I = 2mA (sinking) 17 18.5 20 V IN CLAMP IN V = +15V (for IN -40C to +85C 100 150 MAX5974A/C) IN Supply Current in V = +7.5V (for IN I FA START Undervoltage Lockout MAX5974B/D), when in -40C to +125C 100 250 bootstrap UVLO -40C to +85C 1.8 3 IN Supply Current After Startup I V = +12V mA C IN -40C to +125C 1.8 4 2 Maxim Integrated