AN2600 datasheet(28/30 Pages) STMICROELECTRONICS

28 / 30 page

Test description

AN2600

28/30

As the coupling between the 3.3 V and the auxiliary windings is poor, to help the SMPS to

enter hiccup mode in case of 3.3 V output shorted, the circuitry based on Q10 and Q11 has

been added.

3.8

Conducted emission (EMI) measurements

Conducted emissions measurements at full load and nominal mains voltage have been

performed, using a 50

Ω LISN and a spectrum analyzer with peak detector as shown in

Figure 24 and 25. The emissions are below the limits given by the EN55022 standard for

CLASS B equipment. As the margin between the limits and emission is acceptable, the

power supply is ready for the final compliance test.

3.9

Thermal measurements

In order to check the reliability of the design, thermal measurements using a thermocouple

have been performed.Table 19 and Table 20 list the thermal measurements at nominal input

voltage at ambient temperature (25 °C) for the most critical components under full load.

Figure 24.

Conducted emissions of the

system at full load and Vin=230 V -

phase conducted emission

Figure 25.

Conducted emissions of the

system at full load and Vin=230 V -

neutral conducted emission

02:30:30 Nov 14, 2006

Ref 75 dB

µV#Atten 10 dB

Peak

Log

dB/

W1 S2

S3 FC

Start 150 kHz

Res BW 9 kHz

VBW 30 kHz

Stop 30 MHz

Sweep 881.3 ms (1515 pts)

02:31:12 Nov 14, 2006

Ref 75 dB

µV#Atten 10 dB

Peak

Log

dB/

W1 S2

S3 FC

Start 150 kHz

Res BW 9 kHz

VBW 30 kHz

Stop 30 MHz

Sweep 881.3 ms (1515 pts)

Table 19.

Thermal behavior of the components at primary side

STP5NK60ZFP

case (°C)

STP5NK60ZFP

heatsink (°C)

Trafo core (°C)

Trafo

windings (°C)

Snubber resistor

(°C)

After 30 min

6657435060

After 1 hour

7263495065

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