How to Design High-Voltage, Wide-Input Power Supplies (.PDF Download)

March 27, 2018
How to Design High-Voltage, Wide-Input Power Supplies (.PDF Download)

Power-supply designers frequently encounter projects where the input voltages are much higher compared to the low output voltages usually require to power the target equipment. Typical output needs are 3.3, 5, or 12 V, while inputs can range from about 24 V to as much as 100 V in some cases.

The high input voltage, typically from a battery or power system bus, often forces designers to use more stages and multiple discrete devices to get the desired results, thereby driving up the circuit complexity and cost. But now, such problems can be solved by deploying a range of new wide VIN power-management ICs that help simplify design, reduce BOM cost, and enhance reliability.

Typical Use Cases

Many power systems use high-voltage rails to meet power requirements of the application or achieve efficiency goals. Real-world examples include communication infrastructure, industrial, automotive, and consumer electronic systems. For instance, telecom equipment commonly uses 48-V dc rails that can often swing from about 36 up to 72 V. Power over Ethernet (PoE) equipment uses rail voltages in the 37- to 57-V range. And industrial systems using motors often operate at voltages ranging from 24 to 100 V. These dc voltages come from power buses in other equipment and increasingly from battery supplies. The power buses are the source of power for the low-voltage supplies that operate other equipment.

In general, three types of systems require high voltage. First are the systems that must operate at high-voltage levels. Examples include electric vehicles, drones, and other battery-powered equipment. Second are those systems that need to be protected from high-voltage surges and transients. Third, there are systems that don’t necessarily need high voltage, but it’s desirable for efficiency or safety.

Now wide-input-voltage power-management ICs are available that can significantly simplify the design of high-voltage power supplies. These high-voltage power-management integrated circuits can reduce component count, enhance reliability, and facilitate design reuse. Texas Instruments, using advanced, custom semiconductor-processing methods with different doping concentrations and wider component and lead spacing, has developed a complete product line of wide-VIN ICs that include power managers, dc-dc converters, LDOs, and complete power modules.


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