Summary of Five steps to a great PCB layout for a step-down converter
### Summary This article outlines five essential steps for designing a robust PCB layout for step-down converters, specifically focusing on the TPS62130A. It emphasizes that proper layout is critical for SMPS performance and reliability, preventing issues like voltage regulation errors and device failure. The guide advises copying evaluation module layouts when possible but provides a detailed procedure for custom designs. The first step highlighted is placing and routing the input capacitor immediately after the IC to minimize parasitic inductance.
Parts used in the Step-Down Converter Project:
- Printed circuit board (PCB)
- Switch-mode power supply (SMPS)
- TPS62130A integrated-switch, step-down converter
- Internal MOSFETs
- Integrated loop-compensation circuitry
- Input capacitor
- IC (Integrated Circuit)
- Evaluation module (EVM)
Introduction Especially for switch-mode power supplies (SMPSs), the printed circuit board (PCB) layout is a critical but often under appreciated step in achieving proper performance and reliability. Errors in the PCB layout cause a variety of misbehaviors including poor output voltage regulation, switching jitter, and even device failure. Issues like these should be avoided at all costs, since fixing them usually requires a PCB design modification. However, these pitfalls are easily circumvented if time and thought are spent during the PCB layout process before the first PCBs are ever ordered. This article presents five simple steps to ensure that your next step-down converter’s PCB layout is robust and ready for prototyping. When designing a server, tablet, or electronic point-ofsale machine, a best-practice option with the least risk is to simply copy the PCB layout example found on the evaluation module (EVM) and shown in the datasheet. However, this may not always be possible for various reasons. This article was created for these cases and details a five-step procedure to design a good PCB layout for any TPS62xxx integrated-switch, step-down converter. The internal MOSFETs and integrated loop-compensation circuitry greatly simplify the PCB layout of these devices by reducing the difficulty and time required to do the PCB layout. The versatile TPS62130A is used as the example step-down converter, which can be used in each of the above applications. Figure 1 shows the completed schematic of a typical circuit.
Step #1. Place and route the input capacitor The input capacitor is the single-most important component for reliable operation of any step-down converter. As such, it should be the first component placed in the layout after the IC. Route the capacitor to the IC immediately after it is placed, so that nothing else can be routed in its path. Extra parasitic inductance between the input capacitor’s terminals, both power and ground, and the IC’s PVIN
For more detail: Five steps to a great PCB layout for a step-down converter
- Why is PCB layout critical for switch-mode power supplies?
Errors in PCB layout cause misbehaviors including poor output voltage regulation, switching jitter, and device failure. - What is the best way to avoid PCB design modification costs?
Time and thought should be spent during the PCB layout process before the first PCBs are ever ordered. - Can I copy the PCB layout from an evaluation module?
Yes, copying the layout example found on the evaluation module and shown in the datasheet is a best-practice option with the least risk. - Which component is the single-most important for reliable operation?
The input capacitor is the single-most important component for reliable operation of any step-down converter. - When should the input capacitor be placed in the layout?
It should be the first component placed in the layout after the IC. - How should the input capacitor be routed?
Route the capacitor to the IC immediately after it is placed so that nothing else can be routed in its path. - What do internal MOSFETs simplify?
They simplify the PCB layout by reducing the difficulty and time required to do the layout. - Does the TPS62130A support various applications?
Yes, the versatile TPS62130A can be used in server, tablet, or electronic point-of-sale machine applications.
