LM3150_5X_QS_MOS_Selector by drr53761

VIEWS: 26 PAGES: 2

									Color Code                                                       Description
              User Input, need input even if the previous value exists in the cell
              Not available, internally fixed or optional
              Spread Sheet output for component selection
              Spread Sheet output for user information

                                                                  Description
              General requirements of system : To select the LM3150, enter in the desired output voltage and switching
              frequency values. To select the LM3151/2/3, do not enter in output voltage or switching frequency values--these
  Step1
              parameters will be automatically populated depending on which fixed part is selected. The LM3151/2/3 nominal
              switching frequency value is shown in step 5.
              Select inductor value : Selection of inductance is based on the ripple ratio of inductor current vs output current.
  Step2
              The user selected L value is the actual or "real" inductor value that will be used in the design.
              User MOSFET selection : Select a combination of high side and low side MOSFETs from the pull down menu. If
  Step3       a certain MOSFET is not included in the pull down menu database, then click "Add New MOSFET" and enter in
 Optional     the parameters of the MOSFET you wish to use to be added into the database. The new MOSFET will appear in
              the drop down menu, once it has been added.
              Switching loss calculation : To begin the calculation click the "Start Calculation" button. Then click "OK" when
  Step4       the pop-up window appers. The MOSFET selector will output the most optimized MOSFET combinations for the
              design parameters.
              MOSFET selection : After selecting the recommended or alternative MOSFETs, click "Set MOSFETs & Update
  Step5
              Fsw@Vin(typ)" button to update switching frequency, Fsw.
  Step6       On-time setting Resistor: The value sets the on-time, which determines switching frequency. For the
LM3150 only   LM3151/2/3, Ron is internally fixed.
  Step7       Output capacitor selection : For LM3151/2/3, Cff is internally fixed. The Fsw over Fres ratio will determine the
              minimum output capacitance and min/max ESR value of the output capacitor.
              Input capacitor selection : Cin1 capacitor is optional. It is required when the input power cables are long or the
              relative input impedance of unregulated input power supply. Voltage drops caused by parasitic resistance or the
  Step8
              surge voltage caused by parasitic inductance is big will become large if not properly dampened.

              Current limit setting: For LM3150 current limit can be programmed through the Rlim resistor. For the
  Step9       LM3151/2/3, the current limit is programmed via the Rdson of the low side MOSFET. An additional sense resistor
              can be placed in series with the low side MOSFET to ground, to further decrease the current limit value.
  Step10      Soft start time setting : Set soft-start time, tss, at 30ms as a default
              Feedback Resistors and Cff Values: The feedback resistors set the output voltage which is only applicable to
  Step11
              the LM3150 and not applicable to the LM3151/2/3. The calculated feed forward capacitor, Cff, value is
LM3150 only
              determined by the feedback resistor values.
  Step12      Cvin, Cvcc, Cbst : All values are recommended as a default value.
              Power Dissipation of the IC: These values are provided as a reference of the power dissipation of the IC in the
  Step13
              design. The ambient temperature of the actual design should not exceed the provided temperature values.
              MOSFET Power Dissipation: These values are provided as a reference of the power dissipation of the
              MOSFETs in the design. The temperature rise plus the required maximum ambient temperature should be below
  Step14
              the maximum junction temperature of the MOSFET. The maximum junction temperature of the MOSFET can be
              found in the MOSFET datasheet.
              Output Voltage Ripple: These values are provided as a reference of the output voltage ripple. User selected
  Step15      output capacitance should be greater than minimum output capacitance on Step7. Also user selected ESRo
              should be between minimum ESRo and maximum ESRo on Step7.
LM3150/1/2/3 SIMPLE SWITCHER® Controllers MOSFET Selection and Quick Start Guide
Revision date: Oct. 2008             Ver 1.0
Note: The components calculated in this worksheet are reasonable starting values for a design using the
LM3150/1/2/3 SIMPLE SWITCHER® Controllers. They are not optimized for any particular performance
attribute. The most recent version of this excel file can be found in the product folders of the parts at
national.com
Make sure to input or select values in all of the blue shaded cells even if a value already exists in that cell.
Blue shaded cells require input from user.
Step 1 - General Requirements                          Select the device    LM3150-Adjustable   .                    1
                                                                                   Vin(max) [V]       14.4               Fig1. LM3150-Adj Typical Application Circuit
                                                                                     Vin(typ) [V]     12
                                                                                    Vin(min) [V]      9.6                VIN

                                                            Io, Maximum Ave Load Current [A]          10
                                                                                                                           CIN1          CIN2
                                                                  For LM3150, Target Vout [V]         3.3                                               VIN                    HG                M1
                                  For LM3150, Desired Switching Frequency at Vin(typ) [kHz]           250                                                                     BST                     L                         VOUT
             #NAME?                                                                                                                                     RON                            CBST
                                                                                                                                                  RON                          SW




                                                                                                                                                                  LM3150
Step 2 - Inductor Value                                   Ripple Current Ratio(Iripple/Io) [A/A]      0.3                                                                                                 CFF          RFB2
                                                                                                                                        CBYP            EN                    ILIM
                                                                         Recommended L [μH]           3.3                                                                              RLIM
                                                                                                                                                                                                 M2
                                                                          User Selection L [μH]       3.3                                               SS
                                                                                                                                                                               LG                                               COUT
                                                                                                                                                                                                                       RFB1
                                                                     Peak Inductor Current [A]        #NAME?                                    CSS                           VCC
                                                                                                                                                                                          CVCC
                                                                                                                                                        SGND                 PGND
Step 3 -Optional User MOSFET Selection                          M1, High Side          RJK0305DPB(Renesas)
                                                                                              .                                                         DAP                    FB
                                                                M2, Low Side                  .
                                                                                       RJK0305DPB(Renesas)

                                                                                              Add New MOSFET
Step 4 - Switch Loss Estimation
                                                  minimum Rdson for both MOSFETs[mOhm]                  0

                                                                                              Start Calculation          Fig2. LM3151/2/3 Typical Application Circuit
                                                             User Selection            Recommended Combination
High Side             Part Name                       RJK0305DPB(Renesas)                 BSC027N04LS(Infineon)          VIN

                MOSFET Loss[W]                                        0.62                                 0.32
   Junction to Case Temp. Rise[ºC]                                                                                         CIN1          CIN2
                                                                        1.7                                 0.5                                         VIN                   HG                 M1
Low Side              Part Name                       RJK0305DPB(Renesas)                          IRF6609(IR)                                                                                                  VOUT
                                                                                                                                                                              BST                     L




                                                                                                                                                                LM3151/2/3
                MOSFET Loss[W]                                        1.75                                 0.60                                                                        CBST
                                                                                                                                                                              SW
  Junction to Case Temp. Rise[ºC]                                       4.9                                 0.8
                                                                                                                                        CBYP            EN                     LG                M2
                                                                                                                                                                                                 RSENSE         COUT
                                                       Alternative MOSFET#1                    Alternative MOSFET#2                                     SS
                                                                                                                                                                              VCC
                                                                                                                                                CSS                                       CVCC
High Side                  Part Name                        SI4378DY(Vishay)                  RJK0332DPB(Renesas)
                                                                                                                                                        SGND                 PGND
Low Side                   Part Name                  RJK0329DPB(Renesas)                     RJK0330DPB(Renesas)
                                                                                                                                                        DAP                    FB

 Estimated Loss[W]                            User Selection                 Recommended Combination
  1.4
  1.2
  1.0
  0.8
  0.6
  0.4
  0.2
  0.0
           HS Switching     HS Conduction    LS Conduction       LS Diode            LS Qrr           LS Switching
                                                                Conduction



                                                                                        User Selection
                                                                                                                         List of Components and Parameters
Step 5 - MOSFET Selection                                            High Side                 .                     0                     Description                               Reference      Value              Min Rating
                                                                     Low Side           User Selection
                                                                                               .                     0                Switch Controller                                            LM3150
                                                                                                                               Optional Input Capacitor                   Typ Cin1                 #NAME?                 14.4V
                                                                        Set MOSFETs & Update Fsw@Vin(Typ)
                                                                                                                               Input Ceramic Capacitor                    Typ Cin2                 #NAME?                 14.4V
                                        For LM3151/2/3, Switching Frequency at Vin(typ) [kHz]           NA                                                      Current Ripple RMS                 #NAME?
                                                                                                                                    Vin Bypass Capacitor                  Min Cbyp                  100nF                 14.4V
Step 6 - On-Time Setting Resistor for LM3150                                        Ron [kOhm]          #NAME?                          Output Capacitor                  Min Cout                 #NAME?                  3.8V
                                                                                                                                                                Current Ripple RMS                 #NAME?
Step 7 - Output Capacitor and ESR Limits                                For LM3150, Apply Cff            Yes         1                                                    Max ESR                  #NAME?
                                                                                Fsw over Fres           50                                                                 Min ESR                 #NAME?
                                                                                 Min Cout [μF]          #NAME?                       Softstart Capacitor                   Typ Css                  390nF                      5V
                                                                       RMS Current Ripple [A]           #NAME?                      Bootstrap Capacitor                   Min Cbst                  470nF                     16V
                                                                           Max ESRo [mOhm]              #NAME?                           VCC Capacitor                    Min Cvcc                  2.2µF                     16V
                                                                            Min ESRo [mOhm]             #NAME?                    Feedforward Capacitor                     Min Cff                #NAME?                     3.3V
                                                                   Minimum Ripple on FB [mV]            30                                      Inductor                      Typ L                 3.3µH
             #NAME?                                                                                                                                           Inductor Peak Current                #NAME?
Step 8 - Input Capacitors                                         Min Cin1(Optional, Bulk) [μF]         #NAME?                On-time Setting Resistor                         Ron                 #NAME?                #NAME?
                                                                       Min Cin2(Ceramic) [μF]           #NAME?            Current Limit Setting Resistor                       Rlim                #NAME?                #NAME?
                                                                       RMS Current Ripple [A]           #NAME?                 Current Sense Resistor                       Rsense                   NA                  #NAME?
                                                                                                                               Top Feedback Resistor                           Rfb2                #NAME?                 1/16 W
Step 9 - Current Limit             For LM3151/2/3, Limited Output Current without Rsense [A]            NA                  Bottom Feedback Resistor                           Rfb1                #NAME?                #NAME?
                                               Desired Mimimum Limited Output Current [A]               15
                                     For LM3150, Current Limit Setting Resistor(Rlim) [kOhm]            #NAME?           MOSFETs and Parameters
                                  For LM3151/2/3, Current Sensing Resistor(Rsense) [mOhm]               NA                                   Description          Reference    Value
                                                                                                                                  M1, High Side MOSFET         RJK0305DPB(Renesas)
Step 10 - Soft-Start Time                                       Desired Soft Start Time [mSec]          30                                             Gate-Source Charge       3nC
                                                                 Css, Soft Start Capacitor [nF]         390                                           Total Gate Charge, Qg     9nC
             #NAME?                                                                                                               M2, Low Side MOSFET          RJK0305DPB(Renesas)
Step 11 - Feedback Network for LM3150                      Rfb2, Top Side FB Resistor [kOhm]            #NAME?                                         Gate-Source Charge       3nC
                                                        Rfb1, Bottom Side FB Resistor [kOhm]            #NAME?                                        Total Gate Charge, Qg     9nC
                                                                             Optional Cff [pF]          #NAME?                                                Body Diode Vf    0.85V
                                                                                                                                                            Maximum Rdson    17mOhm
Step 12 - Cvin, Cvcc, Cbst Capacitors                                                  Cbyp [nF]        100                                                  Minimum Rdson    6mOhm
                                                                                       Cvcc [uF]        2.2
                                                                                       Cbst [nF]        470
                                                                                                                                            Simulate This Design Using WEBENCH® Tools
Step 13 - Controller Power Dissipation               Total Power Loss on Controller [W]                 #NAME?                                 To further optimize the design, please visit:
                                          Temperature Rising with 4 Layer PC Board[ºC]                  #NAME?                                        http://webench.national.com/
             Maximum Allowable Ambient Temperature with 4 Layer PC Board@ Typ Vin [ºC]                  #NAME?           Optimization graphs, charts, and electrical/thermal simulation capabilites are available.
                                          Temperature Rising with 2 Layer PC Board[ºC]                  #NAME?                      Note: The WEBENCH recommended BOM may be different than
             Maximum Allowable Ambient Temperature with 2 Layer PC Board@ Typ Vin [ºC]                  #NAME?                                 what is recommended in this spreadsheet.

Step 14 - MOSFET Power Dissipation
                             High Side Junction to Ambient Thermal Resistance [ºC/W]                    50
                                                     Temperature Rise @ Typ Vin [ºC]                    31
                             Low Side Junction to Ambient Thermal Resistance [ºC/W]                     50
                                                     Temperature Rise @ Typ Vin [ºC]                    88

								
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