The MAX5974AETE+T is an active-clamped, spread-spectrum, current-mode PWM controller in 16 pin TQFN package. It provide control for wide-input-voltage, active-clamped, current-mode PWM, forward converters in power-over-Ethernet (PoE) powered device (PD) applications. It is well suited for universal or telecom input range. The device 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, device reduces switching frequency (frequency foldback) to reduce switching losses. It features unique circuitry to achieve output regulation without using an optocoupler. It is used in PoE IEEE 802.3af/at powered devices, high-power PD (beyond the 802.3af/at standard), active-clamped forward DC-DC converters, IP phones and wireless access nodes.
- Supply voltage range is 17V to 20V
- Operating temperature range from -40°C to 85°C, output short circuit protection with hiccup mode
- Sample/hold feedback mode, UVLO threshold of 16V & internal 1% error amplifier
- Peak current-mode control, active-clamped forward PWM controller, regulation without optocoupler
- 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 18V zener clamp on supply i/p
- Internal bootstrap UVLO with large hysteresis, 100μA (typ) start-up supply current
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