www.irf.com

- 19 -

The ballast was measured over the input dimming range:

Control

Input (V)

Frequency

(kHz)

Ballast

Power (W)

Lamp

Voltage

(V rms)

Arc Current

(mA rms)

Arc Power

(W rms)

RLS

Feedback

Voltage

1

57.0

14.6

190

8

1.5

0.07

2

55.7

15.5

201

15

3.5

0.15

3

55.4

18.6

200

30

7.0

0.30

4

55.2

21.3

195

45

10.0

0.45

5

55.0

23.7

187

60

12.0

0.60

6

54.0

26.0

180

80

15.0

0.80

7

52.8

28.5

173

95

19.0

0.90

8

51.5

31.0

167

118

22.0

1.15

9

49.0

33.4

162

136

25.5

1.37

10

48.7

33.5

161

138

26.2

1.40

Table 4: Dimming Test Results

These are average values as there is some frequency modulation occurring at all times as the

system regulates and compensates for impedance changes in the lamp.

The measured results show that the lamp arc current and power are reasonably linear with respect to the

input control voltage:

Arc Current

0

20

40

60

80

100

120

140

160

1

2

3

4

5

6

7

8

9

10

Arc Current

Fig 11. Graph of lamp arc current against control voltage input