LM65680

The LM65680/60/40 is a synchronous buck DC/DC converter offered from a family of devices with ZEN 1 technology designed for low EMI, high power density, and excellent conversion efficiency. Integrated power MOSFETs with low RDS(on) enable up to 8A of output current across a wide input voltage range of 3.5V to 65V.

Phase stackable with synchronized interleaving, the peak current-mode control architecture of the LM65680/60/40 supports accurate current sharing with paralleled phases for higher output currents. AUTO mode enables frequency foldback during light-load operation, giving high light-load efficiency and a no-load input current as low as 2.2µA, which extends operating run-time in battery-powered systems.

A high-side switch minimum on-time of 36ns facilitates large step-down ratios, enabling the direct conversion from 24V or 48V inputs to low-voltage rails for reduced system cost and complexity. The package has several NC pins between critical power pins, which improve the Failure Modes and Effects Analysis (FMEA) result.

The LM65680/60/40 includes several features to simplify compliance with CISPR 11 and CISPR 32 emissions requirements. First, a symmetrical pinout provides excellent input capacitor placement and enables an ultra-low effective value for the power-loop parasitic inductance, which reduces switching losses and improves EMI performance at high input voltage and high switching frequency. A pin-selectable switch-node slew-rate control feature further reduces emissions at high frequencies. To lower input capacitor ripple current and EMI filter size, interleaved operation using a SYNCOUT signal with 180° phase shift works well for cascaded, multichannel or multiphase designs. Resistor-adjustable switching frequency as high as 2.2MHz can be synchronized to an external clock source to eliminate beat frequencies in noise-sensitive applications. Finally, the LM65680/60/40 has dual-random spread spectrum (DRSS), a unique EMI-reduction feature that combines low-frequency triangular and high-frequency random modulations to mitigate disturbances across lower and higher frequency bands, respectively.

Additional features of the LM65680/60/40 include 150°C maximum junction temperature operation, open-drain power-good (PG) indicator for fault reporting and output voltage monitoring, precision enable input for input UVLO protection, monotonic start-up into prebiased loads, dual-input VCC bias subregulator powered from VIN or BIAS, hiccup-mode overload protection, and thermal shutdown protection with automatic recovery.

The LM65680/60/40 comes in a 4.5mm × 4.5mm, thermally enhanced, 26-pin eQFN package with additional pin clearance for increased reliability. Also included are wettable-flank pins to facilitate optical inspection during manufacturing. Leveraging a flip-chip routable leadframe (FCRLF) packaging technique, the LM65680/60/40 with useable current, lifetime reliability, and cost advantages targets applications requiring high power density. The wide input voltage range, low quiescent current consumption, high-temperature operation, cycle-by-cycle current limit, low EMI signature, and small design size provide an excellent point-of-load regulator design for applications requiring enhanced robustness and durability.