Project 1 - 40-V to 80-V adjustable output voltage boost reference design for LIDAR applications

Designing a non-synchronous boost controller for an automotive application involves several considerations, including the layer stack-up, trace width, via size, trace length, and the choice of the number of layers in the PCB.

1. The layer stack-up is crucial for achieving the desired performance and readability of the boost controller. For a simple boost controller, a standard 2-layer PCB may be sufficient. However, depending on the design's complexity, we may consider a 4-layer stack-up for better signal integrity and power distribution.

Possible 2-Layer Stack-up:

• Top Layer (Signal Layer): Signal traces and components.
• Bottom Layer (Ground Plane): Ground plane for signal return paths.

Possible 4-Layer Stack-up:

• Top Layer (Signal Layer): Signal traces and components.
• Inner Layer 1 (Power Plane): Power distribution and additional routing.
• Inner Layer 2 (Ground Plane): Ground plane for signal return paths.
• Bottom Layer (Signal Layer): Additional routing and components.

2.

Trace Width:
To calculate the trace width, we'll need to consider the current-carrying capacity of the trace and the acceptable temperature rise. The IPC-2221 standard or online trace width calculators can be used. Ensure the trace width is adequate for the maximum current requirement.

Via Size:
The via size depends on the current-carrying capacity needed to connect layers. Calculate the required via and the acceptable temperature rise.

Trace Length:
The trace length is a factor in determining the impedance of the transmission lines. Ensure the trace length is optimized to minimize signal degradation, especially for high-frequency components.

3.

Limited Routing Space:
One significant drawback of a 2-layer PCB is the limited routing space. This can be a challenge when dealing with complex designs, high-density components, or maintaining signal integrity for high-speed signals. The limited space may also result in more complex routing and potentially longer traces.

Lack of Power & Ground Planes:
A 2-layer PCB lacks dedicated power and ground planes, which can impact the power distribution and increase the likelihood of noise coupling between traces. Careful design practices can mitigate this, but dedicated planes in a multi-layer PCB provide better power distribution and signal integrity.

Crosstalk and Signal Integrity:
Crosstalk between traces and reduced signal integrity may be more pronounced in a 2-layer PCB due to the absence of dedicated ground and power planes. This can affect the overall performance of the boost controller, especially when dealing with sensitive analog or high-frequency components.