Controller ICs for Intermediate Bus Converters

The new Vishay Siliconix SiP11205 and SiP11206 controllers are designed to work on the primary side of an isolated half-bridge IBC in telecom and network equipment and 1/16 or 1/8 power modules where standard bus voltages such as 48V need to be converted to 12-V or lower intermediate voltages. The new devices simplify designs and reduce solution costs by eliminating the need for separate controller and high-voltage MOSFET driver components for secondary synchronous rectification, while their half-bridge architecture further reduces costs and space requirements by enabling the use of lower-voltage components.

The SiP11205 and SiP11206 controllers step down voltages with >95% efficiency. They feature an input voltage range of 36V to 75V and comfortably handle 100-V transients for 100ms in compliance with ETSI 300-132-2. Integrated ±1.6-A high-voltage MOSFET drivers allow each IC to drive both the low- and high-side switching devices in a half-bridge converter. The oscillator frequency is programmable from 200kHz to 1MHz, the widest such range in the industry, and can be synchronized to an external sync source. Self-driven synchronous rectification eliminates the requirement for secondary-side MOSFET drivers and isolated pulse drivers, reducing costs and simplifying designs.

The SiP11205 features input voltage sensing and feed-forward circuitry that keeps the output voltage within a tight range without the use of optocouplers or voltage feedback circuitry.The SiP11206 differs by allowing the converter to work at the optimal duty cycle within its full input voltage range in DC transformer mode, which greatly improves system efficiency. For designs requiring a fully regulated IBC, Vishay offers the Si9122A half-bridge controller with the SiP11203 or SiP11204 secondary synchronous rectifier driver.

The SiP11205 and SiP11206 offer a comprehensive range of protection features. The controller supply voltage is linearly regulated up to its target voltage with an on-chip pre-regulator circuit. Advanced current monitoring and control circuitry allows the user to set the maximum current in the primary circuit. This feature protects against overcurrent conditions, output short circuits, and errors when paralleling power supplies. Additional features include low input voltage detection, programmable soft-start, and overtemperature protection.

A reference design for a full implementation of an IBC module capable of handling 15A at a 12-V output and operating with greater than 95% efficiency is available for download at www.vishay.com/doc?69636.

Packaged in the MLP44-16 PowerPAK® or TSSOP-16 PowerPAK, samples and production quantities of the SiP11205 and SiP11206 are available now, with lead times of 10 to 12 weeks for larger orders.