Isolated power supply, 36V, H-bridge transformer driver implementing simple and flexible isolated DC-DC design.

SUNNYVALE, CA—August 24, 2011—Maxim Integrated Products (NASDAQ: MXIM) today introduced the MAX13256, an H-bridge transformer driver that provides a wide input voltage range for isolated power supplies. This simple solution enables engineers to quickly design high-efficiency (up to 90%) isolated DC-DC converters. The MAX13256 can drive up to 10W of isolated power and drives the transformer primary with up to 300mA of current from a DC supply as high as 8V to 36V. Users can select their own transformer turns ratio, which defines the output range, allowing them to use virtually any isolated output voltage. This wide supply range eliminates the need for external voltage regulation. Built-in protection features prevent system-level failures. The MAX13256 simplifies bill-of-materials (BOM) complexity by eliminating 16 discrete components, and its high integration in a tiny TDFN package reduces footprint. Combined, these features make the MAX13256 driver a simple way to generate isolated power in smart grid metering applications, industrial equipment, and medical equipment.

Insulation protection for smart meters in smart grids

Smart grid applications utilizing wired interface communications require isolated power supplies to protect against high mains voltages that can damage the internal electronics of devices and power meters. Isolated power is typically generated by transformers and discrete components, increasing solution size and cost. The MAX13256 drives a transformer that provides additional isolation from high mains voltages.

Smart grids have varying input voltage and output power requirements, depending on the type of interface used to communicate with smart meters. The MAX13256's wide 8V to 36V input voltage range meets these diverse power input requirements. The device eliminates the need for external voltage regulation and offers flexible transformer options to meet a wide range of power output requirements.

High integration and high efficiency

The MAX13256 also includes built-in protection features to prevent system-level errors. An adjustable current limit allows for indirect limiting of secondary-side load current. The overcurrent limit is set by an external resistor over a typical range of 215mA to 650mA. An active-low FAULT output asserts when the device detects an overtemperature or overcurrent condition. These built-in thermal and short-circuit protection features ensure safe operation and reduce both cost and PCB space compared to discrete solutions.

Highly integrated H-bridge and transformer modules are typically expensive solutions, limiting users to providing only the system-optimized isolated output voltage. The MAX13256 is ideal for applications requiring a simple, low-cost method for unregulated DC-DC isolation.

The MAX13256's high efficiency (up to 90%) helps reduce heat dissipation, especially in space-critical applications. Additionally, the device offers a low-power mode that reduces overall current consumption to 0.65mA (typ) when the driver is not in use.

The MAX13256 is available in a 10-pin TDFN package and operates over the -40°C to +125°C automotive temperature range. An evaluation kit (EV) is available. For more information, please visit http://www.maxim-ic.com/smartergrid .