LM3424BSTEVAL National Semiconductor, LM3424BSTEVAL Datasheet - Page 33

• Manufacturer Part Number: LM3424BSTEVAL
• Description: LM3424 Constant Current N-Channel Controller with Thermal Foldback for Driving LEDs; Qty per Container: 1/
• Manufacturer: National Semiconductor

10. 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 10 are:
11. 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 11 is:
12. 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 12 is:
IN-PP
is much lower. Since high voltage ceramic capacitor
DS-ON
= 50 mΩ. Determine I
D
:
IN
:
T-RMS
and P
T
:
D
=
33
13. INPUT UVLO
Solve for R
The closest standard resistor is 150 kΩ therefore V
Solve for R
The closest standard resistor is 21 kΩ making V
The chosen components from step 13 are:
14. OUTPUT OVLO
Solve for R
The closest standard resistor is 499 kΩ therefore V
Solve for R
The closest standard resistor is 15.8 kΩ making V
The chosen components from step 14 are:
UV2
UV1
OV2
OV1
:
:
:
:
TURN-ON
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TURN-OFF
HYS
HYSO
is:
:
is:
: