LM3409HVMY/NOPB National Semiconductor, LM3409HVMY/NOPB Datasheet - Page 19

• Manufacturer Part Number: LM3409HVMY/NOPB
• Description: IC LED DRIVR HIGH BRIGHT 10-MSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: HBLED Driverr

Specifications of LM3409HVMY/NOPB

• Constant Current: Yes
• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Automotive
• Type - Secondary: High Brightness LED (HBLED)
• Voltage - Supply: 6 V ~ 75 V
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP Exposed Pad, 10-HMSOP, 10-eMSOP
• Operating Temperature: -40°C ~ 125°C
• Internal Switch(s): Yes
• Efficiency: 97%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Frequency: -
• Current - Output / Channel: -
• Other names: LM3409HVMYTR

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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