AN1523 APPLICATION NOTE
ANNEX 2 - Switch Mode Transformer Specification (continued)
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 closed, 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).
(1H or more)
C (40000 µF or more)
Saturation current @100°C
0,15 0,3 0,45 0,6 0,75 0,9
SWITCH MODE TRANSFORMER SPECIFICATION
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