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Question about tps5450?

bharathi krish
Prodigy 90 points
Other Parts Discussed in Thread: TPS5430, TPS5450, TPS54240, TPS54540

IIn our project  we required different type of Supply voltage 5v,9.9v,12v,15v,18v,24v,-12v with 2Aload,.Could you guide me which one of the TI IC suitable for our requirement. Now we are going with  TPS5450&tps5430,POWER SUPPLY 1.pdf

POWER SUPPLY 1.rar2480.POWER SUPPLY 1.pdf

  • 0
    TI__Guru* 96591 points
    Hello bharathi and welcome to the forums! This question will be better supported in the Non-Isolated DC/DC Applications forum, so I'm moving it now.
  • 0 in reply to Emrys Maier
    TI__Guru**** 191445 points
    That is a complex power scheme. While TPS5430 and TPS5450 may work, there are probably better solutions. TPS5430 and TPS5450 are voltage mode control with internal compensation. The output Land C filter must be carefully matched to the internal compensation. This becomes difficult at higher output voltages. You may want to look at TPS54240 for the positive rails. The negative rail will require greater than 3 A, You would probably want TPS54540. let me know what you think and we can discuss details.
  • 0 in reply to JohnTucker
    Prodigy 90 points

       Thanks for your quick reply,

      

     

  • 0 in reply to JohnTucker
    Prodigy 90 points

    voltage like 12V,15V,18V,24V & tps5450/5430 is suitable for  5V&3.3V supply. Negative voltage  -12V is generate by using Tps54540 its ok or not? . Today i have install the switch pro simulation software . i have simulate  12v,15V,18V,24V voltage, when we get the simulated  output  PWRPD pin pulled up 5V using

    10k resistor  its necessary or not?

  • 0 in reply to bharathi krish
    TI__Guru**** 191445 points

    PWRPD...are you referring to the powerpad?  It will be connected to GND.  It is the thermal heatsinK for the IC.

  • 0 in reply to JohnTucker
    Prodigy 90 points

    Thanks for your quick reply,

                Here along with attached switch pro simulated  output for 12V. Please find it.

    tps1.pdf

  • 0 in reply to bharathi krish
    TI__Guru**** 191445 points
    That is PWRGD not PWRPD. PWRGD is the "power good" signal. It is open drain output. If you want to use it you must pull it up to an external voltage. If you do not want to use it, then you can just leave it open.
  • 0 in reply to JohnTucker
    TI__Guru**** 191445 points
    Need any additional assistance or can I close this out?
  • 0
    Prodigy 90 points

    Dear sir,

                     Sorry for the late response .   As we discussed earlier i have designed  the schematic as well as board layout. Here i attached schematic & board files for your reference schematic and board.zipschematic and board.zip,send your feedback.

    I have  query,

    1.  Now,  i have used different voltage power sources and in layout common GND filling method .whether i need to use to give isolated GND for  each voltage source, could you able to give suggestion?

              2. could you send

                      a) shape to shape clearance of board layout

                       b) signal to signal clearance of board layout

                  3.As per TI datasheet design layout  guidelines, 

    "Power Supply Recommendations
    The design of the device is for operation from an input voltage supply range between 3.5 V and 42 V. Good
    regulation of this input supply is essential. If the input supply is more distant than a few inches from the
    TPS54240 converter, the circuit may require additional bulk capacitance in addition to the ceramic bypass
    capacitors. An electrolytic capacitor with a value of 100 μF is a typical choice"

     just i want to know whether i need  to add additional capacitor depends on  distant  from  input supply or not?

    give me your suggestions                                                                                                                    

    NOTE...I cannot respond to this post for some reason.  It will be few days before I can respond if it is not fixed soon.  Just FYI



                                    

                            

                               

  • 0 in reply to JohnTucker
    Prodigy 90 points

    Dear sir,

                     Sorry  for the late response .   As we discussed earlier i have designed  the schematic as well as board layout. Here i attached schematic & board files for your reference schematic and board.zipschematic and board.zip,send your feedback.

    ti.zipI have  query,

    1.  Now,  i have used different voltage power sources and in layout common GND filling method .whether i need to use to give isolated GND for  each voltage source, could you able to give suggestion?

              2. could you send

                      a) shape to shape clearance of board layout

                       b) signal to signal clearance of board layout

                  3.As per TI datasheet design layout  guidelines, 

    "Power Supply Recommendations
    The design of the device is for operation from an input voltage supply range between 3.5 V and 42 V. Good
    regulation of this input supply is essential. If the input supply is more distant than a few inches from the
    TPS54240 converter, the circuit may require additional bulk capacitance in addition to the ceramic bypass
    capacitors. An electrolytic capacitor with a value of 100 μF is a typical choice"

     just i want to know whether i need  to add additional capacitor depends on  distant  from  input supply or not?

    give me your suggestions    

    I still cannot respond to your thredd...I suggest you start a new one.                                                                                                              

  • 0 in reply to bharathi krish
    TI__Guru**** 191445 points

    I could not open your schematics at all and while the brd file did open, redraws were painfully slow at several minutes, so I could not examine it closely.

    - I almost always use a common ground plane on an internal layer for designs like that (maybe 2)  You will definitely want some exposed copper ground under each IC connected by thermal vias to the exposed thermal pad.  Be generous with this and it will pay you back later.  You may want to use small isolated grounds for sensitive analog returns like the GND termination for the feedback an COMP.  It can be electrically common to the main GND plane, just connect to it at a single point for each small analog GND island or etch run grouping.  This keeps switch currents away from them. 

    - I am enclosing the design rule settings I personally use.  With in reason, they are determined by you own particular PCB vendor and any additional constraints your company may have.  I can't guarantee they will meet your needs, but it is what I use.

    - Based on what I could see of your layout, I think it would be best to add some bulk capacitance.  Maybe one each at the head of each input voltage etch rail.  Another thing,  Those fill areas for VIN seem rather narrow.  I would probably widen them.  Also you are using just wide etch for the switching node of each regulator.  Not generally a good idea.  I would use small copper fills.design rules.pdf

    Hope this helps.