CC2520: ESD causing unknown state

Brian Antheunisse

Part Number: CC2520

Hi guys,

My customer designed in the CC2520, and they are running into trouble. See below:

I have a problem with the CC2520 and ESD.

During some recent testing, we realized that ESD causes the radio to go into an unknown state – the SPI communication seems to continue correctly, but the radio does not transmit or receive anything.

Since the status byte coming from the radio is still fine, we cannot recognize this unknown state from the host device.

The FSM state could be read from the FSMSTAT0 register and perhaps that will help although the reference manual recommends against this.

Thanks,

Brian

over 5 years ago

0 Toby Pan over 5 years ago

TI__Mastermind 28440 points

Hi Brian,

In most cases information from FSMSTAT0 should not be used, but it may prove useful for debugging purposes.

How did the customer design the ESD protection?

Regards,
Toby

0 Brian Antheunisse over 5 years ago in reply to Toby Pan

TI__Expert 5215 points

Let me add another troubling detail. The ESD test causes the device to go into this odd state, but there isn't any permanent damage on the device. A power cycle fixes the problem until the pins are shocked again. Even exercising the reset line on the radio fixes the issue until ESD is applied again.

What is troubling them is that if the status byte comes back without any exceptions, they will never know if the radio (air side) is doing its job or not.

Brian

0 Brian Antheunisse over 5 years ago in reply to Brian Antheunisse

TI__Expert 5215 points

They have added ESD diodes to the pins and it doesn't make any difference.

Will you need scopeshots of this test to understand what may be happening to the part?

Thanks,
Brian

0 Toby Pan over 5 years ago in reply to Brian Antheunisse

TI__Mastermind 28440 points

Yes, if possible, please provide scopeshot(s) and setup.

This sounds like some kind of latchup event has occured.
Also, please be mindful of the Absolute Maximum Ratings, as documented in the datasheet.
The Antenna Circuit Protection of this document may also be useful: www.ti.com/.../sszb130c.pdf

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CC2520: ESD causing unknown state