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ADS8684: EMC test failure on ADS8684

Zoe Yang
Intellectual 2210 points
Part Number: ADS8684

Dear friend,

In the EMC test, when the temperature rises, one channel error occurs. We need you provide some suggestions here.

The working conditions are as follows:

  • Test item: CS Test level: 10V voltage 0.15Mhz-230Mhz Test port: AD input port
  • Test phenomenon: IO port output exceeds the limit
  • Networking: The 4DA (AO) module is connected to the AI ​​interface of the inverter and gives a fixed value (0-10V), and then the inverter gives the same value to the 4AD (AI) through its own AO interface after reading the value of AI. ) module (ADS8684), and then read in the collected value of the 4AD module through EtherCAT and compare it with the output value of the 4DA module. The output power range of the 4DA module is 0-10V, and the input power range of the 4AD module is 0-10V, and the corresponding background software is converted to a code value of 0-20000 for display.

Error report:

  • When the CS test is performed in above networking, the value read by the port A03 (corresponding to chip PIN22, 23) will be reported incorrectly (that is, the 4DA output value does not match the read 4AD input value), and other ports will not report errors . And the error value of each error is 255.

The test problem is roughly located:

  1. During the test, the machine time will report an error if the working time is too long, and will not report an error if the working time is short. So it is suspected that the temperature affects its output.
  2. After using the fan to cool the machine, after several rounds of testing, no error was reported.
  3. During the test, there are two machines, one reports an error and the other does not report an error. The AD chips of the two prototypes are exchanged. The machine that originally reported the error did not report an error, and the machine that did not report an error reported an error. So positioning is a chip problem.
  4. Take two new machines and repeat the steps in 3, the test results are the same.

Problem diagnose: temperature affects the EMC anti-interference performance of ADS8684IDBTR

 

Do we have any recommendation on EMI anti-circuit?  I think higher temperature in EMC test may affect Anti-interference ability.