LM3423MHBKBSTEV/NOPB National Semiconductor, LM3423MHBKBSTEV/NOPB Datasheet - Page 30

• Manufacturer Part Number: LM3423MHBKBSTEV/NOPB
• Description: BOARD EVAL BUCK BOOST LM3423
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3423MHBKBSTEV/NOPB

• Current - Output / Channel: 1A
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 35V
• Features: Dimmable
• Voltage - Input: 4.5 ~ 35V
• Utilized Ic / Part: LM3423
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM3423MHBKBSTEV

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6. PEAK CURRENT LIMIT
Solve for R
The closest standard resistor is 0.04 Ω therefore I
The chosen component from step 6 is:
7. LOOP COMPENSATION
ω
ω
T
To ensure stability, calculate ω
Solve for C
To attenuate switching noise, calculate ω
Assume R
The chosen components from step 7 are:
U0
P1
Z1
is approximated:
is approximated:
is approximated:
FS
LIM
CMP
= 10Ω and solve for C
:
:
P2
:
FS
:
P3
:
LIM
is:
30
8. INPUT CAPACITANCE
Solve for the minimum C
To minimize power supply interaction a 200% larger capaci-
tance of approximately 20 µF is used, therefore the actual
Δv
selection is limited, four 4.7 µF X7R capacitors are chosen.
Determine minimum allowable RMS current rating:
The chosen components from step 8 are:
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
IN-PP
is much lower. Since high voltage ceramic capacitor
DS-ON
= 50 mΩ. Determine I
D
:
IN
:
T-RMS
and P
T
:
D
=