Figure 2. 1KHz, 10% duty cycle dimming signal is approximately 70% LED duty Cycle

Ch1 = DIM signal, Ch2 = VFB 200mV/div = 2A Output current/div

Figure 3. 1KHz, 70% duty cycle dimming signal is approximately 10% LED duty cycle

Ch1 = DIM signal, Ch2 = VFB 200mV/div = 2A Output current/div

10

20

30

40

50

60

70

80

90

100

10

20

30

40

50

60

70

80

90 100

(1‐D) PWM Signal (%)

LED Duty Cycle vs 1‐D

100Hz, 2A

200Hz, 2A

500Hz, 2A

1000Hz, 2A

Figure 4. LED Duty Cycle Vs (1-D) DIM pin Duty Cycle with 12Vin, 2 Luxeon K2s in parallel at 2A

total

12/17/07

SP7600 Evaluation Board Manual

© 2007 Exar Corporation

Page 3 of 5