Power Supply Controller Delivers Five Outputs

Combining the functions of three PWM and PSM converter ICs, the Si9139 single-chip power supply controller converts a 4.5V to 30V input into three individually, tightly regulated dc/dc converter outputs and one 5V output. A precision 3.3V reference is also provided. Achieving power conversion efficiencies in the range of 95%, the new switching power supply controller integrates two main synchronous step-down controllers operating at up to 6A, each with seven fixed outputs from 1.5V to 3.3V, with an adjustable step-up/down controller whose output can be set to any value between 1.24V and 20V with an external resistor divider. The adjustable capability on the third output at 500 mA is said to be an industry first for any such device. An on-board 5V, 30-mA linear regulator provides the fourth output. Other Si9139 features include an internal soft-start and output over-voltage protection and under-voltage shutdown. Price is $2.50 each/50,000. VISHAY SILICONIX, Santa Clara, CA. (408) 988-8000