EVALUATION KIT AVAILABLE Click here for production status of specific part numbers. MAX5974A/MAX5974B/ Active-Clamped, Spread-Spectrum, MAX5974C/MAX5974D Current-Mode PWM Controllers General Description Features The MAX5974 provide control for wide-input-voltage, Peak Current-Mode Control, Active-Clamped Forward active-clamped, current-mode PWM, forward converters PWM Controller in Power-over-Ethernet (PoE) powered device (PD) appli- Regulation Without Optocoupler (MAX5974A/ cations. The MAX5974A/MAX5974C are well-suited for MAX5974B) universal or telecom input range, while the MAX5974B/ Internal 1% Error Amplifier MAX5974D also accommodate low input voltage down to 10.5V. 100kHz to 600kHz Programmable 8% Switching Frequency, Synchronization Up to 1.2MHz The devices include several features to enhance supply Programmable Frequency Dithering for Low-EMI, efficiency. The AUX driver recycles magnetizing cur- rent instead of wasting it in a dissipative clamp circuit. Spread-Spectrum Operation Programmable dead time between the AUX and main Programmable Dead Time, PWM Soft-Start, Current driver allows for zero-voltage switching (ZVS). Under Slope Compensation light-load conditions, the devices reduce the switching fre- Programmable Feed-Forward Maximum Duty-Cycle quency (frequency foldback) to reduce switching losses. Clamp, 80% Maximum Limit The MAX5974A/MAX5974B feature unique circuitry to Frequency Foldback for High-Efficiency Light-Load achieve output regulation without using an optocoupler, Operation while the MAX5974C/MAX5974D utilize the traditional Internal Bootstrap UVLO with Large Hysteresis optocoupler feedback method. An internal error amplifier with a 1% reference is very useful in nonisolated design, 100A (typ) Startup Supply Current eliminating the need for an external shunt regulator. Fast Cycle-by-Cycle Peak Current-Limit, 35ns Typical The devices feature a unique feed-forward maximum Propagation Delay duty-cycle clamp that makes the maximum clamp volt- 115ns Current-Sense Internal Leading-Edge Blanking age during transient conditions independent of the line Output Short-Circuit Protection with Hiccup Mode voltage, allowing the use of a power MOSFET with lower breakdown voltage. The programmable frequency dither- Reverse Current Limit to Prevent Transformer ing feature provides low-EMI, spread-spectrum operation. Saturation Due to Reverse Current The MAX5974 are available in 16-pin TQFN-EP pack- Internal 18V Zener Clamp on Supply Input ages and are rated for operation over the -40C to +85C 3mm x 3mm, Lead-Free, 16-Pin TQFN-EP and -40C to +125C temperature ranges. Applications PoE IEEE 802.3af/at Powered Devices High-Power PD (Beyond the 802.3af/at Standard) IEEE is a registered service mark of the Institute of Electrical Active-Clamped Forward DC-DC Converters and Electronics Engineers, Inc. IP Phones Wireless Access Nodes Security Cameras Ordering Information/Selector Guide appears at end of data sheet. 19-5331 Rev 8 11/20MAX5974A/MAX5974B/ Active-Clamped, Spread-Spectrum, MAX5974C/MAX5974D Current-Mode PWM Controllers Absolute Maximum Ratings IN to GND (V = 0V) ...........................................-0.3V to +26V Maximum Input/Output Current (continuous) EN NDRV, AUXDRV to GND ............................-0.3V to (V + 0.3V) EN .....................................................................................1mA IN RT, DT, FFB, COMP, SS, DCLMP, DITHER/SYNC NDRV, AUXDRV (pulsed for less than 100ns) ..................1A to GND .................................................................-0.3V to +6V Continuous Power Dissipation (T = +70C) A FB to GND (MAX5974A/MAX5974B only) .................-6V to +6V 16-Pin TQFN (derate 20.8mW/C above +70C) ......1666mW FB to GND (MAX5974C/MAX5974D only) ..............-0.3V to +6V Operating Temperature Range ......................... -40C to +125C CS, CSSC to GND ..................................................-0.8V to +6V Maximum Junction Temperature .....................................+150C PGND to GND ......................................................-0.3V to +0.3V Storage Temperature Range ............................ -65C to +150C Lead Temperature (soldering, 10s) .................................+300C 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: 16 TQFN Package Code T1633+4 Outline Number 21-0136 Land Pattern Number 90-0031 THERMAL RESISTANCE, FOUR-LAYER BOARD Junction to Ambient ( ) 48C/W JA Junction to Case ( ) 7C/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. Maxim Integrated 2 www.maximintegrated.com