MeiG Smart product technical information
SLM500
Hardware Design Guide
Page 56
5.PCB Layout
The performance of a product depends largely on the PCB trace. As mentioned above, if
the PCB layout is unreasonable, it may cause interference problems such as card loss. The
way to solve these interferences is often to redesign the PCB. If you can plan a good PCB
layout in the early stage, the PCB traces smoothly, saving a lot of time. Of course, it can also
save a lot of costs. This chapter mainly introduces some things that users should pay attention
to during the PCB layout stage, minimizing interference problems and shortening the user's
development cycle.
The SLM500 module is an intelligent module with its own Android operating system. It
includes sensitive data lines such as high-speed USB and MIPI. It also has strict requirements
on the length and impedance of the signal line. If the high-speed signal processing is not
good, it will cause serious EMI. The problem, more serious will also affect the USB
identification, LCD display, so the PCB design requirements when using the SLM500
module is much higher than the previous 2G module, please read this chapter carefully,
reduce the subsequent hardware debugging cycle.
When using the SLM500 module, the user is required to use at least 4 layers of via holes
for the PCB to facilitate impedance control and signal line shielding.
5.1. Module PIN distribution
Before the PCB layout, first understand the pin distribution of the module, and rationally
layout the related devices and interfaces according to the distribution defined by the pin. Please
refer to Figure 2 to determine the distribution of the function feet of the module.
5.2. PCB Layout Principles
Several aspects of the main attention during the PCB layout phase:
5.2.1. Antenna
Antenna part design, SLM758 module has a total of 4 antenna interfaces, they are:
ANT_MAIN, ANT_DRX, ANT_GNSS, ANT_WIFI. Pay attention to component placement
and RF routing:
The RF test head is used to test the conducted RF performance and should be placed as
close as possible to the antenna pins of the module.
The antenna matching circuit needs to be placed close to the antenna end;
The connection between the antenna pin of the module and the antenna matching circuit
