PRD1209: 10 Vout from 24 Vin at 100 mA

±10 Vout from 24 Vin at 100 mA
Reference Design
PRD1209
FEATURES
Small Size
Low Cost
DESCRIPTION
This application note describes a SEPIC-Cuk converter used to create a dual rail output from a single input
voltage. A SEPIC-Cuk converter uses a SEPIC and a Cuk converter both tied to the same switch node to create
the two separate output rails. In this design, two readily available coupled inductors are used, though a custom
three winding transformer would also work. This design utilizes a cascoded FET (Q1) on the switch node. This
technique allows the use of an inexpensive low voltage regulator chip (ADP1613) to control a higher voltage
converter. In addition it results in very low switching loss, that is offset somewhat by the conduction loss in the
cascoded FET.
Table 1.
Sepcifications
Spec
Units
Vout1
+10V
Volts
Vout2
-10V
Volts
Iout1
0.1
Amps
Iout2
0.1
Amps
Tamb
55
degC
Vinmin
24
Volts
Vinmax
24
Volts
Rev. 0
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owners. Reference designs are not authorized to be used in life support devices or systems.
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Fax: 781.461.3113
©2009 Analog Devices, Inc. All rights reserved.
Reference Design
PRD1209
TABLE OF CONTENTS
Features ......................................................................................................................................................................1
Description .................................................................................................................................................................1
Revision History .........................................................................................................................................................2
Schematic ...................................................................................................................................................................3
Bill of Materials..........................................................................................................................................................3
Graphs ........................................................................................................................................................................5
TABLE OF FIGURES
Figure 1.
Schematic ...............................................................................................................................................3
Figure 2.
Bode Plot (Full Load both channels) .....................................................................................................5
REVISION HISTORY
2/17/2010—Revision 1: Initial Version
Rev. 1 | Page 2 of 6
Reference Design
PRD1209
SCHEMATIC
Figure 1.
Schematic
BILL OF MATERIALS
Table 2.
Des
Bill of Materials
MFG
Component
Specs
Part Number
Pkg
Qty
Area
(mm²)
Height
(mm)
Cost*
ADP1613ARMZ
MSOP-8
1
14.7
1.1
0.700
U1
ADI
Integrated
Switching
Regulator
L1
Coilcraft
47uH, 2200mΩ,
0.38Apk
LPD4012-473
4mm x 4mm
x 1.2mm
1
16.1
1.2
0.600
L2
Coilcraft
47uH, 2200mΩ,
0.38Apk
LPD4012-473
4mm x 4mm
x 1.2mm
1
16.1
1.2
0.600
Q1
Vishay
31 mΩ, 3.1
Vth,60 V
Si4850EY
SO8
1
31
1.75
0.680
Rev. 1 | Page 3 of 6
Reference Design
Des
MFG
D1
PRD1209
Component
Specs
Part Number
Pkg
Qty
Area
(mm²)
Height
(mm)
Cost*
ON
Semi
2 A, 100 V
MBRS1100T3G
SMB
1
21.3
2.4
0.100
D2
ON
Semi
2 A, 100 V
MBRS1100T3G
SMB
1
21.3
2.4
0.100
Cout1
Taiyo
Yuden
1uF, 16V, 9mΩ
EMK107 BJ105KA-T
0603
1
1.3
0.8
0.007
Cout2
Taiyo
Yuden
1uF, 16V, 9mΩ
EMK107 BJ105KA-T
0603
1
1.3
0.8
0.007
Cin1
Murata
0.1uF, 100V,
40mΩ
GRM188R72A104
0603
1
1.3
0.8
0.031
C1
Murata
0.1uF, 100V,
40mΩ
GRM188R72A104
0603
1
1.3
0.8
0.031
C2
Murata
0.1uF, 100V,
40mΩ
GRM188R72A104
0603
1
1.3
0.8
0.031
Rc1
Vishay
5% tolerance
2.32 kOhms
0805
1
2.5
0.5
0.005
Cc1
Vishay
10% tolerance
22 nF
0805
1
2.5
0.5
0.010
Cc2
Vishay
10% tolerance
100 pF
0805
1
2.5
0.5
0.010
Rf1B
Vishay
80.6 kOhms
1% tolerance
0805
1
2.5
0.5
0.005
Rf2
Vishay
11.3 kOhms
1% tolerance
0805
1
2.5
0.5
0.005
Cv5
Murata
1uF,10V,X5R
GRM188R61A105K
0603
1
1.3
0.6
0.010
Css
Vishay
10% tolerance
10 nF
0805
1
2.5
0.5
0.010
Z2
Diodes
Inc.
5.1V, 500 mW
Zener
DDZ9690
SOD-123
1
2.5
1.1
0.026
Rb1
Vishay
95.3 kOhms
5% tolerance
0805
1
2.5
0.5
0.005
Rb2
Vishay
1.78 kOhms
5% tolerance
0805
1
2.5
0.5
0.005
Q2
On
Semi
40V,NPN,300mW
MMBT3904LT1G
SOT-23
1
7.4
1.11
0.020
Totals
22
158.2 max=4.6
Rev. 1 | Page 4 of 6
3.00
Reference Design
PRD1209
GRAPHS
Figure 2.
Bode Plot (Full Load both channels)
Rev. 1 | Page 5 of 6
Reference Design
PRD1209
NOTES
©2009 Analog Devices, Inc. All rights reserved.
Trademarks and registered trademarks are the
property of their respective owners. Error! Unknown document property name.
Rev. 1 | Page 6 of 6