Data Sheet

3. Application Schematic Recommendations
3.1 Power Supply
The WGM160P consists of two main blocks, the microcontroller (EFM32GG11) and the Wi-Fi network co-processor (WF200). The mi-
crocontroller contains an internal dc-dc converter that powers both the microcontroller core and the WiFi chip with a lower supply volt-
age to reduce overall power consumption. All the internal supplies are connected together and supplied by module pin VBAT.
Care should be taken that the supply source is capable of supplying enough current for the load peaks of the power amplifier (which
can go momentarily up to 200 mA), so it is recommended to select a regulator capable of supplying 300 mA. The peaks can be very
fast, and the power supply for the module should be capable of reacting to load changes within 5 µs.
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 the onboard charge pump converters used in RS232 level shifters.
Note that there is a total of about 15 µF of low ESR ceramic capacitors inside the module connected directly on the supply input. 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. Some low-drop linear regulators and some older switched mode regulators are not stable when ceramic
output capacitors are used. The data sheet of the regulator typically lists recommendations concerning suitable capacitors, including
data on ESR range and/or stability curves. A regulator should include the statement “stable with ceramic capacitors”.
3.2 RF Part
When using the WGM160P with an antenna external to the module, be they connectorized off-the-shelf antennas or PCB trace anten-
nas, antenna impedance must be well matched to 50 Ω, achieving better than -10 dB return loss throughout the 2.4-2.48 GHz band to
reduce distortion in the module power amplifier due to impedance mismatch.
The matching should be verified in the final enclosure, and it is recommended to reserve SMD placeholders for external antenna tuning.
The suggested external antenna matching structure is a 3-element PI network.
Unused RF ports (RF2 on both variants or RF1 on the variant without the chip antenna assembled) must be terminated to ground with a
resistor of between 47 and 51 Ω.
UG384: WGM160P Hardware Design User’s Guide
Application Schematic Recommendations
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