5. Hardware Design Guidelines

WGM110 is an easy-to use Module with regard to hardware application design, but certain guidelines must be followed to guarantee

optimal performance. These guidelines are listed in the next sub-sections.

5.1 Power Supply Requirements

WGM110 Module consists of two separate internal blocks, the microcontroller and the Wi-Fi radio block. Individual power supplies are

needed for both the MCU and the Wi-Fi radio blocks.

The WGM110 Module is designed to operate with a 3.3 V nominal input voltage supplied to the two supply inputs as follows:

• The VDDCPU powers the MCU and can be fed with a voltage between 2.0 V and 3.8 V. The regulator supplying VDDCPU should be

able to supply at least 30 mA.

• The VDDPA pad can be supplied with a voltage between 2.7 V and 4.8 V and supplies the RF power amplifier and the internal

switch-mode converter powering the Wi-Fi digital core. VDDPA may draw short peaks up to 350 mA.

In lithium battery powered applications, VDDPA can be connected directly to the battery, while a regulator is needed to supply the

VDDCPU with a lower voltage, as needed by the design. Care should be taken that the supply source is capable of supplying enough

current for the heavy load peaks of the power amplifier.

External high frequency bypass capacitors are not needed because the module contains the required supply filter capacitors. However,

care should be taken to prevent strong switching noise from being superimposed on the supply lines. Such noise can be generated, for

example, by on-board charge pump converters used in RS232 level shifters. Note that there is a total of about 20 µF of low ESR ceram-

ic capacitors on the VDDPA line and approximately 2 µF on the VDDCPU line inside the module. When using external regulators to

generate regulated supplies for the module, the stability of the regulator with the low ESR provided by these capacitors should be

checked. Many low-drop linear regulators and some switched mode regulators are not stable when using ceramic output capacitors.

The datasheet of the regulator typically lists recommendations concerning suitable capacitors, including data on ESR range and/or sta-

bility curves. A regulator with a statement “stable with ceramic capacitors” is recommended.

5.2 PCB Design Guidelines

For optimal performance of the WGM110 Module, please follow these guidelines:

• Place the Module at the edge of the PCB (does not apply to WGM110E), as shown in the figure below.

• Do not place any metal (traces, components, battery, etc.) within the clearance area of the antenna, shown in the figure below as a

white rectangle between the pad rows (does not apply to WGM110E).

• Connect all ground pads directly to a solid ground plane.

• Place the ground vias as close to the ground pads as possible.

• Do not place plastic or any other dielectric material in touch with the antenna.

Figure 5.1. Recommended Application PCB Layout for WGM110A Module

Hardware Design Guidelines

silabs.com | Building a more connected world.

Rev. 1.4 | 17