High-Voltage IC for Resonant Half-Bridge Topology

22nd June 2006

ES Admin

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STMicroelectronics has introduced an advanced double-ended controller specifically designed for the series-resonant half-bridge topology. The new-generation high-voltage IC is said to guarantee excellent performance, allowing the design of fully protected and highly reliable power supplies that are particularly suited for use in applications such as Liquid Crystal Display (LCD) and Plasma Display Panel (PDP) TVs, high-end AC-DC adapters for laptops and game consoles, 80+ initiative-compliant ATX silver boxes, servers and telecom SMPS.

An evolutionary advance over the previous L6598, the new L6599 includes additional features such as a dedicated output for direct Power Factor Corrector (PFC) connection, two-level Over-Current Protection (OCP), latched Disable input, burst-mode operation at light-load, and an input for power-on/off sequencing or brownout protection.

The device operates at 50% complementary duty-cycle with a fixed dead-time inserted to ensure soft-switching. It enables high-frequency (up to 500kHz) operation with high efficiency and low Electromagnetic Interference (EMI) emissions. To drive the high-side switch with the bootstrap approach, the new device combines a high-voltage floating structure, able to withstand more than 600V, with a synchronous-driven high-voltage Lateral Double-diffused Metal Oxide Semiconductor (LDMOS) that eliminates the need for an external fast-recovery bootstrap diode.

The L6599 provides a typical peak current capability for both gate drivers of 0.6A source and 1.2A sink and enables designers to set the operating frequency range by using an externally programmable oscillator.

A non linear soft-start prevents inrush current and minimizes output-voltage overshoot. The device also features a controlled burst-mode operation, thus considerably reducing the average switching frequency and the associated losses under lightly loaded or unloaded conditions.

With the new resonant controller, designers can meet energy-saving requirements even in power-factor-corrected systems. A dedicated output enables the IC to switch off the Power Factor Corrector (PFC) pre-regulator during burst-mode operation, hence eliminating the no-load consumption of this stage.

Other key features of the L6599 include low power consumption (< 30mW), guaranteed latch-up free operation with slew rates up to 50V/ns, a not-latched disable input, and a high-performance Over-Current Protection (OCP) providing complete protection against both overload and short circuits. An additional latched disable input allows easy implementation of Over-Temperature (OTP) and/or Over-Voltage Protection (OVP).

The L6599 is offered in three versions: type L6599N is assembled in a PDIP16 package; L6599D and L6599DTR in a SO16N package. In production now, the IC is $1.20 each in 25,000 unit quantities.