New high-voltage controller improves efficiency and compactness of resonant converters while lowering their noise emissions
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.
Further information is available at www.st.com/powermanagement This press release is also available at www.st.com/stonline/stappl/press/news/year2006/p2023.htm ...... with links to further information on the L6599 About ST's MPA Group (Micro, Power, Analog)
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