Power Electronics

Triple-Output Switching Power Supply Controller

Aimed at power conversion applications in consumer appliances such as set-top boxes, DVD players, notebook computers, and telecom and broadband networks, the Si9139 power supply controller from Siliconix-Vishay takes a 4.5-V to 30-V input voltage and converts it to three individual, tightly regulated dc-to-dc converter outputs, and one 5-V output.

Offering power conversion efficiency in the 95% range, the Si9139 integrates two main synchronous step-down controllers operating at up to 6 A, each with seven fixed outputs from 1.5 V to 3.3 V, and an adjustable step-up/down controller whose output can be set to any value between 1.24 V and 20 V with an external resistor divider. This adjustable capability on the third output at 500 mA is an industry first for any such device. An on-board 5-V, 30-mA linear regulator provides an effective fourth output.

The Si9139's two main dc-to-dc outputs provide individual control for power-up sequencing, power-good signal with delay, internal frequency compensation networks, and automatic boot-strapping.

With a 50-W power rating, the Si9139 works efficiently with the most powerful microprocessors and DSPs with +/-3% total regulation by line, load, and temperature. Additional features include internal soft-start and output overvoltage protection and undervoltage shutdown.

For more information, visit www.vishay.com/docs/71841/71841.pdf.

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