DESCRIPTION

· The MAX5974 series controls wide-input-voltage, active-clamped, current-mode PWM forward converters in PoE PD applications.
· MAX5974A/MAX5974C are suitable for universal or telecom input range, while MAX5974B/MAX5974D support low input voltage down to 10.5V.
· Features include AUX driver for magnetizing current recycling, programmable dead time for ZVS, and frequency foldback for light-load efficiency.
· MAX5974A/MAX5974B achieve output regulation without optocouplers; MAX5974C/MAX5974D use traditional optocoupler feedback.
· Includes internal error amplifier with 1% reference, feed-forward maximum duty-cycle clamp, and programmable frequency dithering for low-EMI operation.
· Available in 16-pin TQFN-EP packages, operating over -40°C to +85°C and -40°C to +125°C.

FEATURES

· Peak current-mode control, active-clamped forward PWM controller.
· Regulation without optocoupler (MAX5974A/MAX5974B).
· Internal 1% error amplifier.
· 100kHz to 600kHz programmable 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.
· Internal 18V Zener clamp on supply input.
· 3mm x 3mm, lead-free, 16-pin TQFN-EP.

APPLICATIONS

· PoE IEEE 802.3af/at powered devices.
· High-power PD (beyond the 802.3af/at standard).
· Active-clamped forward DC-DC converters.
· IP phones.
· Wireless access nodes.
· Security cameras.