LM3429MH National Semiconductor, LM3429MH Datasheet - Page 24

• Manufacturer Part Number: LM3429MH
• Description: IC, LED DRIVER, CNTRL, 14TSSOP
• Manufacturer: National Semiconductor

Specifications of LM3429MH

• Led Driver Application: Automotive, General Illumination
• No. Of Outputs: 1
• Output Current: 1A
• Input Voltage: 4.5V To 75V
• Dimming Control Type: Analogue / PWM
• Topology: Boost, Buck, Buck-Boost, SEPIC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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T
To ensure stability, calculate ω
Solve for C
To attenuate switching noise, calculate ω
Assume R
The chosen components from step 7 are:
8. INPUT CAPACITANCE
Solve for the minimum C
To minimize power supply interaction a 200% larger capaci-
tance of approximately 14 µF is used, therefore the actual
Δv
selection is limited, three 4.7 µF X7R capacitors are chosen.
Determine minimum allowable RMS current rating:
The chosen components from step 8 are:
U0
IN-PP
is approximated:
is much lower. Since high voltage ceramic capacitor
FS
CMP
= 10Ω and solve for C
:
IN
:
P2
:
FS
:
P3
:
24
9. NFET
Determine minimum Q1 voltage rating and current rating:
A 100V NFET is chosen with a current rating of 32A due to
the low R
The chosen component from step 9 is:
10. DIODE
Determine minimum D1 voltage rating and current rating:
A 100V diode is chosen with a current rating of 12A and V
600 mV. Determine P
The chosen component from step 10 is:
11. INPUT UVLO
Solve for R
The closest standard resistor is 150 kΩ therefore V
Solve for R
DS-ON
UV2
UV1
:
:
= 50 mΩ. Determine I
D
:
T-RMS
and P
T
:
HYS
is:
D
=