The MAX5974 provide control for wide-input-voltage, active-clamped, current-mode PWM, forward converters in Power-over-Ethernet (PoE) powered device (PD) applications. The MAX5974A/MAX5974C are well-suited for universal or telecom input range, while the MAX5974B/MAX5974D also accommodate low input voltage down to 10.5V. The devices include several features to enhance supply efficiency. The AUX driver recycles magnetizing current instead of wasting it in a dissipative clamp circuit. Programmable dead time between the AUX and main driver allows for zero-voltage switching (ZVS). Under light-load conditions, the devices reduce the switching frequency (frequency foldback) to reduce switching losses. The MAX5974A/MAX5974B feature unique circuitry to achieve output regulation without using an optocoupler, while the MAX5974C/MAX5974D utilize the traditional optocoupler feedback method. An internal error amplifier with a 1% reference is very useful in nonisolated design, eliminating the need for an external shunt regulator. The devices feature a unique feed-forward maximum duty-cycle clamp that makes the maximum clamp voltage during transient conditions independent of the line voltage, allowing the use of a power MOSFET with lower breakdown voltage. The programmable frequency dithering feature provides low-EMI, spread-spectrum operation. The MAX5974 are available in 16-pin TQFN-EP packages and are rated for operation over the -40°C to +85°C and -40°C to +125°C temperature ranges. Applications * Active-Clamped Forward DC-DC Converters * High-Power PD (Beyond the 802.3af/at Standard) * IP Phones * PoE IEEE® 802.3af/at Powered Devices * Security Cameras * Wireless Access Nodes * Peak Current-Mode Control, Active-Clamped Forward PWM Controller * Regulation Without Optocoupler (MAX5974A/MAX5974B) * Internal 1% Error Amplifier * 100kHz to 600kHz Programmable ±8% Switching Frequency, Synchronization Up to 1.2MHz * Programmable Frequency Dithering for Low-EMI, Spread-Spectrum Operation * Programmable Dead Time, PWM Soft-Start, Current Slope Compensation * Programmable Feed-Forward Maximum Duty-Cycle Clamp, 80% Maximum Limit * Frequency Foldback for High-Efficiency Light-Load Operation * Internal Bootstrap UVLO with Large Hysteresis * 100µA (typ) Startup Supply Current * Fast Cycle-by-Cycle Peak Current-Limit, 35ns Typical Propagation Delay * 115ns Current-Sense Internal Leading-Edge Blanking * Output Short-Circuit Protection with Hiccup Mode * Reverse Current Limit to Prevent Transformer Saturation Due to Reverse Current * Internal 18V Zener Clamp on Supply Input * 3mm x 3mm, Lead-Free, 16-Pin TQFN-EP https://elecena.pl/product/22330460/active-clamped-spread-spectrum-current-mode-pwm-controllers 2022-12-28 https://elecena.pl/product/22330460/active-clamped-spread-spectrum-current-mode-pwm-controllers 2025-01-20