CS5171: SEPIC LED Driver

DN06004/D
Design Note – DN06004/D
SEPIC LED Driver
Device
Application
Input Voltage
Output Power
Topology
I/O Isolation
CS5171
Miners Light
4 Vdc
2W
SEPIC
NO
Other Specifications
Output Voltage
Nominal Current
Output 1
Output 2
Output 3
Output 4
3.5 V
350 mA
N/A
N/A
N/A
N/A
N/A
N/A
Minimum Efficiency
70%
Operating Temp. Range
0 to +70˚C
Circuit Description
Key Features
This application is for the LED driver to be powered from a
source that can be higher or lower than the LED voltage
and must be efficient as possible. The SEPIC topology
was chosen. The schematic in the following page shows a
4 V SEPIC LED driver using the CS5171 as a DC-DC
boost regulator. The CS5171 operates at 260 KHz with
about 65% efficiency with a 4.0V input. The
MBRM110LT1 is a 10V schottky diode with a forward drop
of < 0.3V. The NCS2001 operates as amplifier for the
current sense voltage across R2 and drives the feedback
pin on the CS5171.
• SEPIC LED Driver
• 350 mA LED Current
July 2006, Rev. 0
www.onsemi.com
1
DN06004/D
Schematic
D1
C2
U1
C1
1
10nF
2
3
C3
R1
200nF
5.1kOhm_5%
+ 4 Volts
4
Vc
Vsw
FB
Test
SS
PGnd
AGnd
Vcc
MBRM110LT1
8
LED1
7
22uF
6
L1
5
22uH
C4
22uF
L2
CS5171
22uH
J1
R2
C5
2.2uF
.56Ohm_5%
R3
5.1kOhm_5%
1 Out Vcc
2
Vee
3
U2
+
-
NCS2001
5
4
R5
R4
1.0kOhm_5%
July 2006, Rev. 0
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1.0kOhm_5%
2
DN06004/D
Layout
July 2006, Rev. 0
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3
DN06004/D
July 2006, Rev. 0
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4
DN06004/D
Bill of Materials 1
Ref.
Qty.
Description
Value
Package
Vendor
Vendor PN
SO-8
SOT23-5
ON Semi
ON Semi
CS5171ED8
NCS2001SN2T1
Powermite
ON Semi
MBRM110LT1
STAR / O
LUXON
LXHL-NW98
Phoenix Contact
1715035
805
smd
805
smd
1206
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
ECJ-2VB1H103K
EEF-CD1B220R
ECJ-2VB1C224K
EEF-CD1B220R
ECJ-3YB1C225K
5.1 K ohm
.56 ohm 1%
5.1 K ohm 1%
1 K ohm 1%
1 K ohm 1%
1206
1206
1206
1206
1206
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
22 uh
22 uh
smd
smd
Coil_craft
Coil_craft
U1
U2
1
1
IC Boost Controller
Amplifier
D1
1
Diode
LED1
1
J1
1
C1
C2
C3
C4
C5
1
1
1
1
1
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
.01 uf
22 uf
200 nf
22 uf
2.2 uf
R1
R2
R3
R4
R5
1
1
1
1
1
Resistor
Resistor
Resistor
Resistor
Resistor
L1
L2
1
1
Inductor
Inductor
PCB
1
CS5171 SEPIC raw board
10 V Schottky
Digikey #
PCC103BNCT-ND
PCE3168CT-ND
PCC1816CT-ND
PCE3168CT-ND
PCC1931TR-ND
P5.1KECT-ND
P.56RCT-ND
P5.1KFCT-ND
P1.0KFCT-ND
P1.0KFCT-ND
MSS6132-223MXD
MSS6132-223MXD
CS5171 Rev A
1
© 2006 ON Semiconductor.
Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor
does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to
assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated
with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its
products at any time, without notice.
Design note created by Roger Miller, e-mail: [email protected]
July 2006, Rev. 0
www.onsemi.com
5
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