Datasheet

C
O
D1
R
OV2
R
OV1
1A
I
LED
R
SNS
R
FS
C
FS
C
OV
Q2
V
IN
V
IN
OVP
nDIM
LM3421
AGND
V
IN
PGND
DDRV
DAP
GATE
EN
COMP
VIN
CSH
RCT
IS
HSP
RPD
VCC
HSN
L1
C
BYP
R
LIM
Q1
C
CMP
R
CSH
R
T
R
UV2
R
UV1
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
R
HSN
R
HSP
C
T
C
IN
10V ± 70V
LM3421, LM3421-Q1
LM3423, LM3423-Q1
www.ti.com SNVS574E –JULY 2008–REVISED MAY 2013
Design Example
DESIGN #1 - LM3421 BUCK-BOOST Application
SPECIFICATIONS
N = 6
V
LED
= 3.5V
r
LED
= 325 mΩ
V
IN
= 24V
V
IN-MIN
= 10V
V
IN-MAX
= 70V
f
SW
= 500 kHz
V
SNS
= 100 mV
I
LED
= 1A
Δi
L-PP
= 700 mA
Δi
LED-PP
= 12 mA
Δv
IN-PP
= 100 mV
I
LIM
= 6A
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Product Folder Links: LM3421 LM3421-Q1 LM3423 LM3423-Q1