AN3040

Experimental results

Doc ID 16181 Rev 2

15/27

4

Experimental results

The schematic of the tested board is shown in Figure 3. The board has been tested for

efficiency, power factor, total harmonic distortion and thermal behavior for the input voltage

range. Table 2 and Table 3 show the results obtained for a 45-minute test.

All the results are very good. Efficiency is approximately 85%, the power factor corrector is

constantly 0.9 and THD is lower than 10%.

With regard to the thermal behavior, it is easy to deduct fromTable 3 that there is a good

safety margin from the maximum junction temperature of the MOSFET.

4.1

Start sequence

begins charging. When the voltage at the TCH pin reaches VCHP (4.63 V), the same

capacitor is discharged following an exponential decrease steered by the time constant; this

defines the preheating time.

During this time, the EOI pin is forced to ground and the switching frequency is set by the

oscillator to the preheating value. When the voltage at the TCH pin drops down to

1.53 V, the EOI pin is exponentially charged according to a time constant that defines the

ignition time.

Table 2.

4 x 18 W T8 board performance

η

PF

THD(%)

85

82.3

34.4

83.6%

0.9

0.99

6

110

80

34.4

86%

0.997

0.99

4.4

140

78.5

34.4

87.6%

0.555

0.99

5.5

185

78.4

34.4

87.7%

0.424

0.98

6.5

230

77.7

34.4

88.5%

0.344

0.97

8.5

265

77.2

34.4

89.1%

0.301

0.95

10

Table 3.

4 x 18 W T8 thermal results of critic system components

Ambient

temp (°C)

Temp

Temp

Temp

Temp

L6585DE(°C)

85

25

54

55

120

44

110

25

53

54

108

43

140

25

53

54

102

43

185

25

53

54

94

43

230

25

53

54

84

43

265

25

53

54

74.5

43