Download
Share
Print this page
  1. Manuals
  2. Brands
  3. Power integrations Manuals
  4. Switch
  5. LinkSwitch-LP Series
  6. Application note

Power integrations LinkSwitch-LP Series Application Note

Flyback design guide
Hide thumbs

Advertisement

Quick Links

Download this manual
LinkSwitch-LP
Flyback Design Guide
Application Note AN-39
Introduction
The LinkSwitch-LP family is designed to replace inefficient
line frequency linear transformer based power supplies with
output powers < 2.5 W in applications such as cell/cordless
phones, PDAs, digital cameras, and portable audio players.
LinkSwitch-LP may also be used as auxiliary supplies employed
in applications such as white goods.
LinkSwitch-LP combines a high voltage power MOSFET switch
with an ON/OFF controller in one device. It is completely
self-powered from the DRAIN pin, has a jittered switching
frequency for low EMI and is fully fault protected. Auto-restart
limits device and circuit dissipation during overload and output
short circuit conditions while hysteretic over-temperature
protection disables the internal MOSFET during thermal
faults. EcoSmart
technology enables designs to easily attain
®
< 150 mW no-load consumption, meeting worldwide energy
efficiency requirements.
LinkSwitch-LP is designed to operate without the need for a
primary-side clamp circuit for output powers below 2.5 W and
Figure 1. Basic Circuit Schematic Using LinkSwitch-LP in a Clampless™ Design.
®
D1
L1
1N4937
3.3 mH
L
C1
90-265
10 µF
VAC
400 V
N
D4
1N4007
LinkSwitch
U1
LNK564P
thus, dramatically reduces component count and total system
cost. Figure 1 shows a LinkSwitch-LP based 2 W power supply
without a primary-side clamp. The LinkSwitch-LP family
has been optimized to give an approximate CV/CC output
characteristic when feedback is provided from an auxillary or
bias winding on the transformer. This is ideal for applications
replacing a line frequency transformer, providing a compatible
output characteristic but with reduced overload, short circuit
current and variation with input line voltage.
Scope
This application note is for engineers designing an isolated
AC-DC flyback power supply using the LinkSwitch-LP family of
devices. It provides guidelines to enable an engineer to quickly
select key components and complete a transformer design for an
application requiring either a constant voltage (CV) or constant
voltage and constant current (CV/CC) output. To simplify the
task of transformer design, this application note refers directly
to the PI Xls design spreadsheet that is part of the PI Expert™
design software suite.
C5
D6
220 µF
T1
UF4002
25 V
EE16
2
7
1
6
4
D5
1N4005
5
R1
37.4 kΩ
R2
C3
3 kΩ
0.1 µF
50 V
PI-4063-101005
R4
6 V,
2 kΩ
0.33 A
RTN
C4
0.33 µF
50 V
July 2006

Advertisement

loading
Need help?

Need help?

Do you have a question about the LinkSwitch-LP Series and is the answer not in the manual?

Questions and answers

Subscribe to Our Youtube Channel

Related Manuals for Power integrations LinkSwitch-LP Series

Summary of Contents for Power integrations LinkSwitch-LP Series

  • Page 1 ® LinkSwitch-LP Flyback Design Guide Application Note AN-39 Introduction thus, dramatically reduces component count and total system cost. Figure 1 shows a LinkSwitch-LP based 2 W power supply The LinkSwitch-LP family is designed to replace inefficient without a primary-side clamp. The LinkSwitch-LP family line frequency linear transformer based power supplies with has been optimized to give an approximate CV/CC output output powers <...

  • Page 2: Quick Start

    AN-39 Quick Start Start design Enter power supply specifications: Input voltage range and frequency, output voltage, output current and VI characteristic, feedback type, loss allocation factor, diode conduction time and input capacitance Select LinkSwitch-LP based on Table 4 (see data sheet) and reflected output voltage (V ) to 80 V Select a standard transformer design...
  • Page 3 AN-39 Step-by-Step Design procedure Step 1 – Enter Application Variables: VAC , VAC Nominal Peak Power Point Maximum Peak , CV/CC spec, P , Clamp and Feedback type, Power Point η, Z, t and C OUT(TYP) Determine the input voltage range (VAC and VAC ) from Table 1.
  • Page 4 AN-39 0.33 µF DC BUS 50 V HV DC LinkSwitch-LP LNK564P 0.1 µF 50 V PI-4138-070706 Figure 4. Circuit Schematic for High Performance CV/CC Output Characteristic. subject to unit-to-unit variation caused by the difference in the For designs using Filterfuse™ use the values in parenthesis, transformer (bias to secondary coupling and leakage inductance.
  • Page 5 AN-39 Optocoupler with Zener Bias Winding Feedback Optocoupler with TL-431 as as Reference (Figure 4, U2 (Figure 1) Reference (Figure 4) Replaced with Zener Typical Output Characteristics Load (mA) Load (mA) Load (mA) Cost Higher Highest Component count Lowest component count Higher component count Highest component count Ease of Design...
  • Page 6 AN-39 Reflected Output Voltage, V performance and not the peak drain voltage that limits the use of Clampless designs to < 2 W. However if a bias winding is This parameter is the secondary winding voltage reflected added which uses a slow diode (1N400x series) that peak in back to the primary through the turns ratio of the transformer EMI is reduced as the bias acts as a clamp, damping out the (during the off time of the LinkSwitch-LP).
  • Page 7 AN-39 Variables referenced in Step two are found in the Enter The gray override cells can be used to enter the core and bobbin LinkSwitch-LP Variables section of the spreadsheet (see parameters directly. This is useful if a core is selected that is Figure 6).
  • Page 8 AN-39 Calculated Bias Winding Turns and Voltage N 1500 Gauss (150 mT) may produce audible noise from the When a bias winding is used, the number of turns and voltage transformer and for such designs the acceptability should be developed by the winding are displayed. The relatively large verified.
  • Page 9 AN-39 ≤ 1 W ≤ 3 W Suggested 85-265 IN1-4 VAC Input Stage 3.3 mH 10 µF AC IN 400 V PI-4240-110305 PI-3772-121603 PI-3773-121603 PI-3774-121603 Component RF1: 8.2 Ω, 1 W RF1: 8.2 W, 1 W L1*: 3.3 µH, 0.06 A RF1: 8.2 W, 1 W Selection Guide Fusible...
  • Page 10 AN-39 VR Range Series Number Type Package Manufacturer 1N5817 to 1N5819 Schottky 20-40 Leaded Vishay SB120 to SB1100 Schottky 20-100 Leaded Vishay 11DQ50 to 11DQ60 Schottky 50-60 Leaded 1N5820 to 1N5822 Schottky 20-40 Leaded Vishay MBR320 to MBR360 Schottky 20-60 Leaded SS12 to SS16 Schottky...
  • Page 11 AN-39 ISP × ESR. ISP is the secondary peak current, which is calculated To illustrate this, Appendix A provides two reference in the Transformer Secondary Design Parameters section of designs that in many cases may eliminate the need to design the spreadsheet.
  • Page 12 AN-39 220 µF 9 V, 1N4937 3.3 mH UF4002 EE16 25 V 3 kΩ 0.22 A 90-265 10 µF 400 V 1N4005 1N4005 36.5 kΩ LinkSwitch 0.33 µF 50 V LNK564P 3 kΩ 0.1 µF 50 V PI-4145-101005 Figure 10. 9 V, 220 mA Design Using the Standard Transformer Design Described in Appendix B. These two transformers have been optimized for EMI Table 9 lists the transformer, reflected output voltage and the performance and the rest of the circuit can be adjusted to...
  • Page 13 AN-39 LNK-LP Transformer R1 (kΩ) R2 (kΩ) 0.325 LNK562 63.45 24.61 04.25 LNK563 63.45 24.61 LNK564 63.45 24.61 0.26 LNK562 76.95 30.75 0.34 LNK563 76.95 30.75 LNK564 76.95 30.75 0.21 LNK562 90.45 36.88 0.28 LNK563 90.45 36.88 0.33 LNK564 90.45 36.88 0.18 LNK562...
  • Page 14 AN-39 APPENDIX – A Input Voltage Range – Universal Output Voltage – 6V Reference LinkSwitch-LP Standard Transformer Output Current – 330 mA Designs The Transformer assumes a bias winding; hence there is no Transformer A restriction on using a 2-layer primary winding. Transformer A was optimized for the following specifications: 60 Hz 1 min., Electrical...
  • Page 15 AN-39 APPENDIX - B Input Voltage Range – Universal Output Voltage – 9 V Transformer B Output Current – 220 mA Transformer B was optimized for the following specifications: The Transformer assumes a bias winding; hence there is no restriction on using a 2-layer primary winding. 60 Hz 1 min., Electrical from Pins 1-2 to...
  • Page 16 AN-39 Bobbin Drawing Figure 15. Bobbin Drawing for all the Transformers Used in Table 9. Uses a 5+5 Pin EE16 Bobbin With Extended Creepage to Allow Safety Compliance 7/06...
  • Page 17 AN-39 Notes 7/06...
  • Page 18 AN-39 Notes 7/06...
  • Page 19 AN-39 Notes 7/06...
  • Page 20 For the latest updates, visit our website: www.powerint.com Power Integrations reserves the right to make changes to its products at any time to improve reliability or manufacturability. Power Integrations does not assume any liability arising from the use of any device or circuit described herein. POWER INTEGRATIONS MAKES NO WARRANTY HEREIN AND SPECIFICALLY DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.