We may know that to design a new power supply is not so easy.The design of switching power supplies requires significant attention to the details, from component placement and thermal analysis to test carefully for a wide range of operating conditions.
Switching power supplies are inevitable in today’s designs. They’re power-efficient and thermal-efficient, with various schemes available for every application. Switching regulators solve the power dissipation and efficiency problem by operating via pulse-width modulation (PWM). There are multiple considerations when designing the switching power supply circuit, though, and price shouldn’t be the only driver for the component selection. A complete understanding of all these elements will help you select the most cost-effective part for your design.
The voltage and nominal current required at the output of the switching dc-dc stage is the most obvious factor to consider in the design. Datasheets only tell part of the story. Don’t take their stated output capabilities for granted! In fact, you might want to calculate the maximum output power you might need from the switching power circuit and make sure the device can provide it with some safety margin on top (see “Choosing The Right Switching Regulator”).
The same part number with different packaging will offer different thermal abilities, leading to different output capabilities. Different packages have different thermal resistance, and some packages are better at handling the thermal release than others. Space is important in the component package selection, but so is ease of manufacturing, overall airflow considerations, and board layout. Compact design (due to limited space or footprint) requires a good evaluation that the thermal heat will be released correctly without affecting other sections of the equipment since this gradient my cause significant issues in ultra-low-noise circuits, high-performance systems, optical circuitry, and more.
Linear Technology’s LT1170 comes in different packages, from the popular TO-220 to the DIP-8 and the 8-SOIC, 16-SOIC, and D2PAK-5 surface-mount versions. The SOIC-16 offers the poorest thermal performance with 150°C/W, while the D2PAK offers 25°C/W when 2.8 square inches of 1-oz cooper is used in the layer. So, the power available from the LT1170 (as with any switching supply component) will depend on the package, but also configuration, components, layout, and heatsinking.
Get an evaluation board of your target switching regulator to evaluate its performance with your particular application. The switching frequency might be an issue, and testing this component with the rest of your system will tell you if you need additional filtering or heatsinks or if you need to use a different part.
We should also think about the Input Conditions, Thermal And Heatsinking Issues,Component Quality and PCB Area Layout, And Footprint.etc.