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AN1523 APPLICATION NOTE

ANNEX 2 - Switch Mode Transformer Specification (continued)

SWITCH MODE TRANSFORMER SPECIFICATION

2362.0019 C

CUSTOMER CODE

ISSUE A

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reproduced, published, disclosed or used in any form with out written permission of ELDOR CORPORATION S.p.A.

DOC.N.

PAG. 4 / 6

2.3

Temperatures

2.3.1

Temperature raise of the primary coil

The raising in primary winding shall be made in the following condition: Vin nom. and all loads at maximum current,

except that for the Audio output that must be adjusted at 50% Imax.

Raise of temperature after 4 hours must be lower than 55

°C

2.3.2

Maximum allowable temperatures

In the application, TV set with cabinet close d, at the maximum allowable ambient temperature (See IEC68-1 clause

4.6.2) and at the maximum working conditions (see § 2.3.1) after 4 hours the temperature of the transformer must

be = 115

°C.

To satisfy the above conditions it is raccomanded to provide the SMT with sufficient cool air flow around it.

2.4

Core saturation

Test must be performed in the following way:

a) The SMT must be placed in oven at ambient temperature of 100

°C for 2 hours.

b) Using the circuit as per figure, connect the primary winding to LCR meter operating at frequency of 1

kHz and output voltage of 1 V.

c) Superimpose through the power supply a dc current and read on the LCR meter the correspondent

value of the inductance. Do this up to a current value of I peak max input current.

d)

The value of the inductance must not shows saturation (0.7Lp).

A

CHOKE

(1H or more)

SPECIMEN

C (40000

µF or more)

LCR

METER

+

Saturation current @100

°C

0,50

0,60

0,70

0,80

0,90

1,00

1,10

0

0,15

0,3

0,45

0,6

0,75

0,9

I (A)