LM3409EVAL National Semiconductor, LM3409EVAL Datasheet - Page 7

• Manufacturer Part Number: LM3409EVAL
• Description: BOARD EVALUATION FOR LM3409
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3409EVAL

• Current - Output / Channel: 1A
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 15V
• Features: Dimmable
• Voltage - Input: 6 ~ 42 V
• Utilized Ic / Part: LM3409
• Kit Contents: Board, Datasheet
• Svhc: No SVHC (15-Dec-2010)
• Kit Features: Drives 4 LEDs At Maximum Average LED Current 1A From DC Input Voltage 24V
• Mcu Supported Families: LM3409
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Alternate Designs
Alternate designs with the LM3409 demonstration board are
possible with very few changes to the existing hardware. The
evaluation board FETs and diodes are already rated higher
than necessary for design flexibility. The input UVLO can re-
main the same and the input capacitance is sufficient for most
designs, though the input voltage ripple will change. Other
designs can be evaluated by changing R1, R4, L1, and C5.
Specification /
Component
Dimming Method
V
V
f
I
Δi
R1
R4
L1
C5
SW
LED
IN
O
LED
Design 1
PWM
24V
14V
500 kHz
1A
450 mA
15.4 kΩ
0.2Ω
22 µH
None
Design 2
Analog
12V
7V
250 kHz
3A
70 mA
15.4 kΩ
0.08Ω
33 µH
1 µF
7
The table below gives the main specifications for four different
designs and the corresponding values for R1, R4, L1, and C5.
The RMS current rating of L1 should be at least 50% higher
than the specified I
analog dimming range, while designs 1 and 3 are optimized
for best PWM dimming range. These are just examples, how-
ever any combination of specifications can be achieved by
following the Design Procedure in the LM3409/09HV
datasheet.
Design 3
PWM
36V
24V
450 kHz
700 mA
250 mA
25.5 kΩ
0.3Ω
68 µH
None
LED
. Designs 2 and 4 are optimized for best
Design 4
Analog
42V
35V
300 kHz
2A
60 mA
24.9 kΩ
0.12Ω
68 µH
1 µF
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