LM3429MH National Semiconductor, LM3429MH Datasheet - Page 20
LM3429MH
Manufacturer Part Number
LM3429MH
Description
IC, LED DRIVER, CNTRL, 14TSSOP
Manufacturer
National Semiconductor
Datasheet
1.LM3429MHNOPB.pdf
(34 pages)
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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Part Number
Manufacturer
Quantity
Price
Part Number:
LM3429MH
Manufacturer:
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Quantity:
20 000
Company:
Part Number:
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Manufacturer:
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A high frequency compensation pole (ω
attenuate switching noise and provide better gain margin. As-
suming R
value of the pole and the RHP zero of the system (shown as
a maximizing function):
The total system loop gain (T) can then be written as:
Buck
Boost and Buck-boost
8. INPUT CAPACITANCE
Set the nominal input voltage ripple (Δv
the required capacitance (C
Buck
Boost
Buck-boost
Use D
solving for C
solving for C
The minimum allowable RMS input current rating (I
can be approximated:
Buck
Boost
MAX
FS
to set the worst case input voltage ripple, when
= 10Ω, C
IN
IN
in a buck-boost regulator and D
in a buck regulator.
FS
is calculated according to the higher
IN
):
IN-PP
P3
) can be used to
) by solving for
MID
= 0.5 when
CIN-RMS
)
20
Buck-boost
9. NFET
The NFET voltage rating should be at least 15% higher than
the maximum NFET drain-to-source voltage (V
Buck
Boost
Buck-boost
The current rating should be at least 10% higher than the
maximum average NFET current (I
Buck
Boost and Buck-boost
Approximate the nominal RMS transistor current (I
Buck
Boost and Buck-boost
Given an NFET with on-resistance (R
nominal power dissipation (P
10. DIODE
The Schottky diode voltage rating should be at least 15%
higher than the maximum blocking voltage (V
Buck
Boost
Buck-boost
T
):
T-MAX
DS-ON
):
), solve for the
RD-MAX
T-MAX
T-RMS
):
):
) :