Where can we get the EMC test data/report of ESP-WROOM-02?

[YimingLi]

Hi Espressif,

Can we get the EMC test data/report of the ESP-WROOM-02? And where?

We notice that the ESP8266 chip is highly intergrated inside-chip with nearly all RF circuits including the Switch/Balun/PA/LNA.... Meanwhile, the only RF external to the chip, matching components, occupy very small room and are very close to the antenna. Andthe datasheet says ESP8266 chip is FCC/CE/... certificate.

So, why is there still a metal shield required on the ESP-WROOM-02, just like other wifi modules which use chips with much more external RF circuit?

We hope reference it to evaluate the necessity of the metal shield of the ESP8266 module certificate.

Thanks in advance.

Yiming

[pratik]

The compliance regulations are extremely complex and are meant to be observed on the system level, i.e. even if you use 5 compliant modules to design a system that is non-compliant - your device will fail certification.
Bodies like FCC specify different regulations for intended radiation and non-intended radiation from devices. While the ESP8266 may not radiate too much as a chip, it does feature very high speed flash interface and crystal oscillator.
To make the system robust and reliable, a metal shield is very helpful. However, if you use a 4- or 6- layer PCB and design your product right with proper via stitching and layout, I'm sure you can get around to a compliant design without a shield. Shield just makes things a little easier.
We offer some firmware that facilitates system regulation testing, which may be found here:
http://www.espressif.com/sites/default/ ... 170410.zip

[YimingLi]

Thanks, Pratik. Appreciated.

That is, a well-designed board might lead the metal shield unnecessary. As we know, even there is a crystal and SPI Flash, the frequencies of them are not too high, and the size is not too large to be handled easily.

Best,

Yiming

[pratik]

Correct, but typically for FCC related design aspects, anything >10 MHz should be considered "high frequency".
For example, a 40 MHz flash speed needs 40MHz square wave for clock signal - and 40 MHz square wave contains very high frequency components (if you do the fourier transform). So a 40 MHz clock may contain 1 GHz frequency too, if it has sharp edges.
However, 26 MHz crystal frequency is sine and does not contain high frequency.
Do consider all that for FCC certifications!