LM3409HVMYX National Semiconductor, LM3409HVMYX Datasheet - Page 19

• Manufacturer Part Number: LM3409HVMYX
• Description: LM3409 LM3409HV PFET Buck Controller for High Power LED Drives; Package: MINI SOIC EXP PAD; No of Pins: 10; Qty per Container: 3500/Reel
• Manufacturer: National Semiconductor

3. AVERAGE LED CURRENT
Determine I
Assume V
The closest 1% tolerance resistor is 0.1 Ω therefore the I
is:
The chosen component from step 3 is:
4. OUTPUT CAPACITANCE
No output capacitance is necessary.
5. INPUT CAPACITANCE
Determine t
Solve for C
Choose C
Determine I
The chosen components from step 5 are:
IN
ADJ
IN-MIN
:
L-MAX
ON
IN-RMS
= 1.24V and solve for R
:
:
:
:
SNS
:
LED
19
6. PFET
Determine minimum Q1 voltage rating and current rating:
A 100V, 3.8A PFET is chosen with R
= 20nC. Determine I
The chosen component from step 6 is:
7. DIODE
Determine minimum D1 voltage rating and current rating:
A 100V, 3A diode is chosen with V
P
The chosen component from step 7 is:
D
:
T-RMS
and P
T
:
D
DS-ON
= 750mV. Determine
= 190mΩ and Q
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