SNVA866A February   2019  – January 2023 LM5155 , LM5155-Q1 , LM51551 , LM51551-Q1

 

  1.   How to design an Isolated Flyback using LM5155
  2.   Trademarks
  3. 1Introduction
  4. 2Example Application
  5. 3Calculations and Component Selection
    1. 3.1 Switching Frequency
    2. 3.2 Transformer Selection
      1. 3.2.1 Maximum Duty Cycle and Turns Ratio Selection
      2. 3.2.2 Primary Winding Inductance Selection
    3. 3.3 Current Sense Resistor Calculations
      1. 3.3.1 Current Sense Resistor and Slope Compensation Resistor Selection
      2. 3.3.2 Current Sense Resistor Filter Selection
    4. 3.4 MOSFET Selection
    5. 3.5 Diode Selection
    6. 3.6 Output Capacitor Selection
    7. 3.7 Input Capacitor Selection
    8. 3.8 UVLO Resistor Selection
    9. 3.9 Control Loop Compensation
      1. 3.9.1 Feedback Resistor Selection
      2. 3.9.2 RPULLUP Selection
      3. 3.9.3 Optocoupler Selection
      4. 3.9.4 RLED Selection
      5. 3.9.5 Crossover Frequency Selection
      6. 3.9.6 Determine Required RCOMP
      7. 3.9.7 Determine Required CCOMP
  6. 4Component Selection Summary
  7. 5Small Signal Frequency Analysis
    1. 5.1 Flyback Regulator Modulator Modeling
    2. 5.2 Compensation Modeling
  8. 6Revision History

4 Component Selection Summary

GUID-F7C851D7-149A-4177-80E3-D29A884FC5CB-low.gifFigure 4-1 Application Circuit
GUID-D3575AAF-44F8-4960-98DD-179C0C16A911-low.gifFigure 4-2 Efficiency vs. ILOAD
GUID-721E8D13-AE15-4607-B730-A8C93E039739-low.gifFigure 4-4 Load Step: ILOAD 2 A to 4 A, VSUPPLY = 18 V
GUID-944A3247-A87F-4E0F-8ACD-ACB76CECDDAD-low.gifFigure 4-3 Control Loop Response VSUPPLY = 18 V, ILOAD = 4 A
GUID-4C9232AE-BE64-4471-A20B-116846CBC80B-low.gifFigure 4-5 Thermal Image: VSUPPLY = 18 V, ILOAD = 4 A
GUID-E92F9FBD-5B4D-435E-89BB-F7A25D79C27B-low.gifFigure 4-6 LM5155EVM-FLY Schematic
Table 4-1 List of Components
Item Qty Value Description Package
Ref		 Part
Number		 Mfr
C1 1 680pF CAP, CERM, 680 pF, 100 V, +/- 10%, X7R, 0603 0603 GRM188R72A681KA01D MuRata
C2 1 100uF CAP, Polymer Hybrid, 100 uF, 50 V, +/- 20%, 28 ohm, 10x10 SMD 10x10 EEHZC1H101P Panasonic
C3 1 0.1uF CAP, CERM, 0.1 uF, 50 V, +/- 20%, X7R, 0805 0805 08055C104MAT2A AVX
C4, C5 2 1uF CAP, CERM, 1 uF, 50 V, +/- 10%, X7R, 0805 0805 08055C105KAT2A AVX
C6 1 4.7uF CAP, CERM, 4.7 uF, 50 V, +/- 10%, X7R, 1206 1206 C3216X7R1H475K160AC TDK
C7, C8 2 270uF CAP, Aluminum Polymer, 270 uF, 25 V, +/- 20%, 0.027 ohm, D10xL12.7mm SMD D10xL12.7mm PCV1E271MCL1GS Nichicon
C9, C10 2 10uF CAP, CERM, 10 uF, 25 V,+/- 10%, X7R, 1210 1210 885012209028 Wurth Elektronik
C11, C13 2 0.1uF CAP, CERM, 0.1 uF, 25 V, +/- 10%, X7R, 0603 0603 C1608X7R1E104K080AA TDK
C12 1 1000pF CAP, CERM, 1000 pF, 25 V, +/- 10%, X7R, 0603 0603 GRM188R71E102KA01D MuRata
C14 1 0.01uF CAP, CERM, 0.01 uF, 50 V, +/- 10%, X7R, AEC-Q200 Grade 1, 0603 0603 GCM188R71H103KA37D MuRata
C15 1 4.7uF CAP, CERM, 4.7 uF, 35 V, +/- 10%, X5R, 0603 0603 GRM188R6YA475KE15D MuRata
C16 1 0.33uF CAP, CERM, 0.33 uF, 100 V, +/- 10%, X7R, C3216X7R2A334K130AA TDK
C17 1 1uF CAP, CERM, 1 uF, 16 V, +/- 20%, X7R, AEC-Q200 Grade 1, 0603 0603 GCM188R71C105MA64D MuRata
C18 1 0.1uF CAP, CERM, 0.1 uF, 50 V, +/- 10%, X7R, 0603 0603 C1608X7R1H104K080AA TDK
C19 1 470pF CAP, CERM, 470 pF, 50 V, +/- 10%, X7R, 0603 0603 GRM188R71H471KA01D MuRata
C20 1 4.7uF CAP, CERM, 4.7 µF, 25 V,+/- 10%, X6S, AEC-Q200 Grade 2, 0603 0603 GRT188C81E475KE13D MuRata
C21 1 220pF CAP, CERM, 220 pF, 50 V, +/- 5%, C0G/NP0, 0603 0603 C0603C221J5GACTU Kemet
C22 1 0.01uF CAP, CERM, 0.01 uF, 16 V, +/- 10%, X7R, 0603 0603 GRM188R71C103KA01D MuRata
C24, C26 2 0.22uF CAP, CERM, 0.22 µF, 16 V,+/- 10%, X7R, AEC-Q200 Grade 1, 0603 0603 CL10B224KO8VPNC Samsung
C28 1 1000pF CAP, CERM, 1000 pF, 2000 V, +/- 10%, X7R, 1812 1812 1812GC102K1A AVX
D1 1 40V Diode, Schottky, 40 V, 10 A, AEC-Q101, TO-277A TO-277A SS10P4-M3/87A Vishay-Semiconductor
D2 1 100V Diode, Switching, 100 V, 0.2 A, SOD-323 SOD-323 MMDL914-TP Micro Commercial Components
D3 1 150V Diode, Superfast Rectifier, 150 V, 1 A, SMA SMA ES1C-13-F Diodes Inc.
D4 1 30V Diode, Schottky, 30 V, 0.2 A, SOT-323 SOT-323 BAT54SWT1G Fairchild Semiconductor
H1, H2, H3, H4 4 Bumpon, Cylindrical, 0.312 X 0.200, Black Black Bumpon SJ61A1 3M
J1, J2 2 Terminal Block, 5mm, 2-pole, TH TH, 2-Leads, Body 10x9mm, Pin Spacing 5mm ED350/2 On-Shore Technology
J3, TP9 2 TEST POINT SLOTTED .118", TH Test point, TH Slot Test point 1040 Keystone
J4 1 Header, 2.54mm, 5x1, Tin, TH Header, 2.54mm, 5x1, TH PEC05SAAN Sullins Connector Solutions
Q1 1 100V MOSFET, N-CH, 100 V, 13 A, DQJ0008A (VSONP-8) DQJ0008A CSD19533Q5A Texas Instruments
R1 1 15.0 RES, 15.0, 1%, 0.5 W, 1210 1210 ERJ-14NF15R0U Panasonic
R2, R11 2 100 RES, 100, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 ERJ-3EKF1000V Panasonic
R3 1 0 RES, 0, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 RMCF0603ZT0R00 Stackpole Electronics Inc
R4 1 30.1k RES, 30.1 k, 1%, 1 W, AEC-Q200 Grade 0, 2512 2512 CRCW251230K1FKEG Vishay-Dale
R5, R8, R10, R24, R26 5 0 RES, 0, 5%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 ERJ-3GEY0R00V Panasonic
R6, R9, R13 3 100k RES, 100 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW0603100KFKEA Vishay-Dale
R7 1 10.0 RES, 10.0, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060310R0FKEA Vishay-Dale
R12 1 0.02 RES, 0.02, 1%, 1 W, 0612 0612 PRL1632-R020-F-T1 Susumu Co Ltd
R14 1 1.00k RES, 1.00 k, 1%, 0.1 W, 0603 0603 ERJ-3EKF1001V Panasonic
R16, R22 2 9.76k RES, 9.76 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06039K76FKEA Vishay-Dale
R17 1 86.6k RES, 86.6 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW060386K6FKEA Vishay-Dale
R18 1 4.99k RES, 4.99 k, 1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 CRCW06034K99FKEA Vishay-Dale
R19 1 30.0k RES, 30.0 k, 1%, 0.1 W, 0603 0603 RC0603FR-0730KL Yageo
R20, R21 2 1.00k RES, 1.00 k, 0.1%, 0.1 W, AEC-Q200 Grade 0, 0603 0603 ERA3AEB102V Panasonic
T1 1 21uH Transformer, 21 uH, SMT 13.97x18.25mm 750317933 Wurth Elektronik
TP1, TP2 2 Test Point, Miniature, Red, TH Red Miniature Testpoint 5000 Keystone
TP3, TP4, TP8 3 Test Point, Miniature, Black, TH Black Miniature Testpoint 5001 Keystone
TP5 1 PC Test Point, SMT PC Test Point, SMT 5017 Keystone
U1 1 2.2-MHz Wide Input Nonsynchronous Boost, Sepic, Flyback Controller, DSS0012B (WSON-12) DSS0012B LM5155DSST Texas Instruments
U2 1 Optocoupler, 2.5 kV, 100-200% CTR, SMT PS2811-1 PS2811-1-M-A California Eastern Laboratories
U3 1 Low-Voltage (1.24V) Adjustable Precision Shunt Regulators, 3-pin SOT-23, Pb-Free DBZ0003A LMV431BIMF/NOPB Texas Instruments