By Frank De Stasi and Denislav Petkov, Systems and Application Engineers, Texas Instruments
Energy efficiency and miniaturisation of systems is a constant goal in the electronics industry. New systems need to deliver more capability than their previous incarnations while at the same time keeping or reducing their overall size and energy consumption. In some cases, systems that were previously using inefficient but easy-to-design linear voltage regulators may need to convert to switching regulator solutions. In other cases, existing switching regulator solutions need to shrink in size and free up board space for additional features in the new system.
In many new systems there is a need for a highly efficient, small, and easy-to-implement voltage regulator solution. One way to fill this need is to use an integrated power module. The SIMPLE SWITCHER nano-modules portfolio of easy-to-use, synchronous step-down DC/DC converters are capable of delivering up to 2A of load current from an input voltage of up to 17V, providing exceptional efficiency in a very small solution size.
High system efficiency
The use of synchronous rectification in DC/DC step-down switching converters provides two benefits. First, the internal power MOSFET replaces the external Schottky diode required for older non-synchronous solutions, saving PCB area and bill of materials (BOM) cost. Second, the voltage drop across the power MOSFET is much smaller than that of a Schottky diode. This results in higher efficiency at heavy loads. Some applications also have maximum consumption requirements in system standby mode.
The new SIMPLE SWITCHER nano-modules also feature high light-load efficiency to keep the system standby energy consumption to a minimum.
Nano-scale packaging
Miniaturisation often requires packaging innovation. Devices like the LMZ2050x and LMZ2170x incorporate world-class package technology to fit the regulator in a total volume of only 21 mm3.
The package of these new modules contains the regulator and inductor in a small 3.5 mm x 3.5 mm x 1.75 mm volume, saving board space and eliminating the time and expense of inductor selection. All that is required for a complete power supply is to add a feedback network and output and input filter capacitors. The LMZ2050x and LMZ2170x require only five external components for a simple converter solution.
The overall solution size on a single-sided board can be fitted in 40 mm2 or less.
If further size optimization is needed, the system designer may elect to place components on both sides of the PCB. This can achieve a converter solution as small as 25 mm2.
Design time and ease-of-use factor
As systems engineers are pressed with deadlines to implement new system features, easy-to-use voltage regulators can become an important factor. In general, power modules offer reduced system design time due to a higher level of integration and component selection simplicity. If the system designer is replacing a linear regulator implementation with a switching solution, modules certainly can be an ideal fit. Some designers may feel uneasy about replacing linear regulators with switchers because of electromagnetic interference (EMI) concerns, but SIMPLE SWITCHER nano-modules demonstrate excellent EMI performance when tested against the CISPR22 Class B specifications.
Other designers replacing switching regulators with modules may be worried about the thermal performance of the integrated solution versus a solution with external inductor and a Schottky diode (in non-synchronous rectification). The nano-module packaging features low package thermal resistance, which allow for proper heat dissipation. Also, high conversion efficiency translates into lower heat generation and an overall cooler system. It is only a plus if the converter manufacturer also provides some sort of design tools to allow the system designer early insight into the performance of the regulator and streamline the design process. The SIMPLE SWITCHER concept provides for an easy to use complete design with a minimum of external components and TI’s WEBENCH design tools. WEBENCH Power Designer includes features such as external component calculation, electrical simulation, and thermal simulation using a demo board layout.
The tool allows system designers to export the module design schematic and PCB layout to their favorite CAD tool format and cut-and-paste in their design. The PCB layout is a critical part of the power converter design. Having a good layout example up front, whether it comes from the nano-module datasheet or a WEBENCH design, can eliminate many headaches when the first hardware arrives back from the factory.
Overall, the latest additions to the SIMPLE SWITCHER nano-module portfolio provide system designers with a highly efficient, small, and easy-to-implement voltage regulator solution.
