LM3424MH/NOPB National Semiconductor, LM3424MH/NOPB Datasheet - Page 33

• Manufacturer Part Number: LM3424MH/NOPB
• Description: IC LED DVR BUCK/BOOST 20-TSSOP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: High Power, Constant Currentr

Specifications of LM3424MH/NOPB

• Constant Current: Yes
• Topology: Flyback, PWM, SEPIC, Step-Down (Buck), Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: No
• Type - Primary: Automotive
• Type - Secondary: High Brightness LED (HBLED)
• Frequency: 2MHz
• Voltage - Supply: 4.5 V ~ 75 V
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP Exposed Pad, 20-eTSSOP, 20-HTSSOP
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 1A
• Internal Switch(s): Yes
• Efficiency: 96%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Other names: LM3424MH

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:
: