AFE031: Wondering what the resolution to the AFE failure issue was

Hi Lawrence, 

Could you describe your failure issues in AFE031 in your application? I see the thread you mentioned and it is linked below. 

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/997054/afe031-afe031-powerline-communications-plc-analog-front-end-failure?tisearch=e2e-sitesearch&keymatch=AFE031%252520powerline%252520communications%252520%252528PLC%252529%252520analog%252520front-end%25252C%252520FAILURE#

Please note that the AFE031's damage observation may be similar, but the root causes of the damage may be different. Since I have no information about your setup, I am unable to speculate what is going on. 

One of the common mistakes in AFE031's output setup is shown in red block. The marked red block is a current steering circuit, where it will redirect overcurrent conditions to Vpa node instead of the overcurrent is directly sinked into AFE031. The selection of D2 and D4 schottky diodes have to have lower forward diode voltage and faster response time than the ESD diodes that is internal to the AFE031's output pins. The diode types are noted in the AFE031 EVM User's guide. 

The ARE031EVM's reference design is implemented with overvoltage and overcurrent protection.  D3 is used to clamp overvoltage conditions and D2, D4 and D1 are used to redirect the majority over current conditions to GND via power amplifier's external paths. If these components are not specified properly, damages could occur to the internal AFE031 power amplifier. This is only one of the damage scenario.  

https://www.ti.com/lit/ug/sbou223/sbou223.pdf?ts=1700848573309&ref_url=https%253A%252F%252Fwww.google.com%252F

I need to see your PLC schematic and configuration of your application design in order to understand the root causes of the damage. Please submit "friendship" inquiry via E2E inquiry, if you do not wish to post your schematic in the publish forum. E2E has a private message forum, where the discussion is private, or I can provide you with the  TI email address once we have established the contact, if you'd like to discuss the matter via our internal email. 

If you have other questions, please let me know.  

Best,

Raymond 

We are having failures where the AFE PA output is failed as a short and if the esd diodes are measured in the device they measure less than 0.1V as a forward voltage.  Attached is our schematic of the AFE output.

Hi Lawrence, 

From your schematic, the schottky diodes seem to be ok, let us assume that these are not the issues. 

I see the other possible issues. Please short L201 1uH inductor in the schematic for now. If there is 1uH inductor in series with the load, it should be on the other side of current steering diode. As is, the Ldi/dt may cause unwanted voltage spikes and it could cause overvoltage issues. There is typo in the inductor's placement in the AFE031's datasheet and it is revised in the AFE031 EVM User's Guide.  

In addition, what is 4.7Ohm resistor in series with AFE031's output for. Please short R220 or remove 4.7Ohm resistor as well.  

Please let me know the PLC's secondary powerline characteristics. what are +/-190V operating frequency? Are these DC or AC powerline? 

Under what testing or operating conditions, the AFE031 is failed (if you have observed);  and how long AFE031 is failed after the working DUT is being installed. I would like to understand the failure scenarios per your application. 

Best,

Raymond