LM3409HVMYX National Semiconductor, LM3409HVMYX Datasheet - Page 22

• 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

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3. AVERAGE LED CURRENT
Determine I
Assume V
The closest 1% tolerance resistor is 0.2 Ω therefore I
The chosen component from step 3 is:
4. OUTPUT CAPACITANCE
Assume r
Solve for C
Choose C
The chosen component from step 5 is:
5. INPUT CAPACITANCE
Determine t
Solve for C
Choose C
D
O
IN
ADJ
O-MIN
:
IN-MIN
= 2 Ω and determine Z
L-MAX
ON
:
= 1.24V and solve for R
:
:
and :
:
C
:
SNS
:
LED
is:
22
Determine I
The chosen component from step 5 is:
6. PFET
Determine minimum Q1 voltage rating and current rating:
A 70V, 5.7A 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 60V, 5A diode is chosen with V
The chosen component from step 7 is:
IN-RMS
:
T-RMS
and P
T
:
D
= 750mV. Determine P
DS-ON
= 190mΩ and Q
g
D
=
: