ST’s family of resonant controllers includes primary controllers for double-ended (half-bridge) topologies, designed to provide high efficiency under any load conditions, as well as high noise immunity (zero voltage switching operation).
The L6598, the 1st generation of ST’s resonant controllers, implements an HV half bridge driver that directly drives two power MOSFETs and has a dedicated timing section to set soft start duration and minimum operating frequency.
The L6599 and L6599A, ST’s second and third generation of resonant controllers, offer increased operating frequency (up to 500 kHz), additional features such as burst-mode operation to reduce the consumption at light load operation, a dedicated pin for direct connection with the PFC controller, and improved protection features, such as two-level OCP (frequency-shift and latched shutdown), brownout protection and latched disable input.
These controllers are widely used in LCD TVs, all-in-one PCs, high-power LED lighting and AC-DC adapters (>90 W).
L6699 resonant controller boosts SMPS efficiency
The new L6699, ST’s 4th generation resonant controller, has an innovative design optimized to reduce power supply complexity, form factor and costs.
It improves the efficiency both at light and full load. Under light load conditions, the device is compliant with the most demanding energy regulations in the market, achieving 50% efficiency at 250 mW output power, as required by ErP lot 6 regulation. This level of efficiency is possible thanks to reduced internal consumption (1 mA of quiescent current) and ST’s patented internal auto-adjusted deadtime, which allows the designer to increase the magnetizing inductance of the transformer in order to reduce the magnetizing current flowing in the primary side.
The device also offers a set of advanced and ST-patented protection features, such as the anti-capacitive mode, and an enhanced soft-start for extra-smooth startup to increase system reliability and lifetime. The embedded smart burst-mode feature prevents any possible audible noise during light load or no load operation.
The L6699 is pin-to-pin compatible with previous generation devices.