AN3978

EMC testing

Doc ID 022179 Rev 1

13/19

Table 3 and Table 4 indicate application surge immunity. Supply voltage and output ports

have been tested in common mode (CM) as well as in differential mode (DM). When surge

has been applied to supply lines in common mode, the application worked without any

influence, see Table 3. Differential mode influences the L6370Q operation due to the fact

that high energy surge pulses cause short-time power interruptions on the chip supply.

Immunity of the output in differential mode depends on the supply voltage capacitive filter.

Selection of the supply capacitor (C1) dramatically influences the achieved test result.

Practical tests showed that applications with a low ESR (0.074

Ω) 100 μF capacitor passed

3 kV successfully and failed at -3.5 kV. The same result has been achieved with a standard

220

μF SMD capacitor (ESR = 0.18 Ω). Applications with a standard 100 μF SMD (ESR =

0.34

Ω) capacitor usually failed at -2.5 kV, and with a 47 μF SMD capacitor (ESR = 0.68 Ω),

at -2 kV.

Table 4.

Application surge test results, surge applied to output lines

Configuration

Mode

Surge test signal amplitude, test results at polarity (+ / -)

1 kV

1.5 kV

2 kV

2.5 kV

3 kV

Standard

demonstration

board configuration

Common (CM)

B / B

B / B

B / B

B / B

B / B

Differential (DM)

B / B

B / B

B / B

B / B

B / B