EMC requirements

AN3031

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Doc ID 16144 Rev 1

6.5

Conducted disturbance tests

(according to the IEC 61000-4-6)

The conducted radio frequency interference test must be applied on all input pins of the

system. The frequency range is 150 kHz to 80 MHz, with 80% amplitude modulation of a 1

kHz sinusoidal wave. A CDN (coupling/decoupling network) or a current coupling clamp (as

described in the IEC 61000-4-6 standard) must be used to apply stress to the system. The

continue to operate as intended. No loss of function or performance is acceptable (criteria

“A” according to the IEC 61131-2 standard).

6.6

Reverse analog input polarity tests

The test procedure is described in the IEC 61131-2 standard (paragraph 5.4.4.5 of Ed2 of

the standard). A signal of reverse polarity (negative voltage) for unipolar analog inputs is

applied for 10s. The result of this test shall be as stated by the manufacturer. Each input of

the SCLT3-8BT8 device may be biased to a reverse polarity. This case corresponds to a

connection mistake, or a reverse biasing that is generated by the demagnetization of a

monitored inductive solenoid. The input involved withstands the high reverse current up to

20 mA; its corresponding bit in the data frame remains in a logic low state. The other inputs

remain operational. Considering the supply operation, a reverse blocking diode can be

connected between the module ground and the common COM pin to protect the application

(especially the serial resistors) from a spurious reverse supply connection. The thermal

management of this accidental situation is described in Section 4: SPI communication

speed calculation.