Power Supply Design Software Suite from Power Integrations

Explains Doug Bailey, vice president of marketing: “Many consumer products require multiple voltage rails – for example, a DVD player may use 3.3 V for the logic, 5 V for analog components, 12 V for the drive mechanism motors and -12 V for a vacuum fluorescent display. The most cost-effective way to achieve this is to design a single transformer and arrange the secondary winding turns-ratios to generate the required output voltages. The difficulty is to manage cross regulation between the rails so that, for example, the 3.3 V logic rail does not fall to 2.5 V when the 12 V drawer-opening motor is activated. This requires a detailed knowledge of transformer design and, typically, many iterations. The new PI Expert release incorporates real-world engineering experience and some highly complex mathematics to deliver the best design given an array of user-selectable input parameters.”

PI Expert v7.0 also incorporates a physical model of the transformer. The new software calculates whether the transformer windings required to achieve the power-transfer goals of the transformer will fit into the winding window of the user-selectable core and bobbin combination. If the windings do not fit the window, PI Expert v7.0 presents alternate solutions. The transformer design from PI Expert v7.0 can be submitted to the PI RTSS (Rapid Transformer Sampling Service) for rapid prototyping and delivery. Sample services are available today from Power Integrations, ICE Components and Wurth Elektronik.

In a flyback topology power supply, the clamp circuit is used to recover leakage inductance energy and protect other parts of the power supply from high voltages during line surges and rapid load transitions. Clamp implementation cost can be traded off against power supply efficiency and ruggedness. The new PI Expert v7.0 includes clamp circuit design algorithms which calculate the necessary component values, and provide all corresponding component part numbers for the optimum solution.

All switch-mode power supplies generate EMI (Electro-Magnetic Interference) as a consequence of switching high voltages at high frequencies. Suppression of the conducted portion of the EMI is done by adding filtering components on the input of the power supply, but these components are a cost-overhead because they do not add to the power conversion function. Based on a knowledge of the circuit design and software input parameters, PI Expert v7.0 selects an EMI filter design, calculates and optimizes the component values and provides part numbers for implementing the most cost-effective filter.