LM3409QHVMY/NOPB National Semiconductor, LM3409QHVMY/NOPB Datasheet - Page 22

• Manufacturer Part Number: LM3409QHVMY/NOPB
• Description: IC LED DVR HIGH BRIGHT 10MSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3409QHVMY/NOPB

• Constant Current: Yes
• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Automotive, General Purpose
• Type - Secondary: High Brightness LED (HBLED)
• Voltage - Supply: 6 V ~ 75 V
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
• Operating Temperature: -40°C ~ 125°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Frequency: -
• Current - Output / Channel: -
• Other names: LM3409QHVMYTR

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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
=
: