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EMI issue BQ500412

alex ch70
Prodigy 120 points
Other Parts Discussed in Thread: BQ500412, BQ51013B

Hi all.

I’m using BQ500412 IC for wireless power transfer.

I’m using BQ51013B IC for wireless power receiver.

During the EN regulation verification I came across with major EMI issue (radiated emission).

I test my design against EN300 300-2 standard that applies for radio equipment in the frequency range of 9 KHz to 25MHz.

The BQ500412 is Qi compliance, WPC1.1 standard that working with the frequency range of 120 KHz to 205 KHz.

This IC is a variable frequency device.  It will start at 175 kHz.  At light load the frequency will go up at heavy loads the frequency will go down.

 

According to EN300 300-2 standard the limit are:

Between 135 KHz – 140 KHz the limit is 42dBuA/m

Between 140 KHz – 148.5 KHz the limit is 42dBuA/m

Between 148.5 KHz – 30MHz the limit is -5dBuA/m

 

The meaning of this is that there is a big gap between the limit above 148.5 KHz and under 148.5KHz. (30dBuA/m gap)

 

Basically any emission over the frequency 148.5 KHz is “unwanted emission”

 

I think it very odd that there is suck kind of international compliance and standard that has this kind of low limit (and even “unwanted emission” on that FREQ according to Annex J on the EN300300 standard)

That’s located exactly in the middle of international standard.

 

According to TI EVAL board, TI completed EMI testing on the bq500412 EVM in 2013 before release of the EVM, in the following standards:

1.)    For EU - EN61326-1

2.)    For US – FCC Part 18

3.)    For Canada – ICES-001

 

 

Here is my question is:

  • Why TI test this EVAL board only against EN61326-1 (These are for the unintentional radiator portion as well as the digital circuitry portion of the device) and not test it also against the EN300 300-2 standard that applies for radio equipment?
  • EN61326-1 doesn’t even go down to the transmit frequency of your device.  TI radiated testing is from 30MHz – 1000MHz, why TI use only this test?
  • Is there possibility that we scan according to the wrong standard?
  • Is there a specific standard to wireless power transmitters, if so can you please provide me this standard?
  • Can you please share all of the testing standards that done by TI on this device?