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DC-DC using TPS61089 & webench

VT
Genius 3300 points
Other Parts Discussed in Thread: TPS61089

1.Need to design dc-dc for
Input: 6V-8.6V dc
Output: 12V/2A

Entire load is for 20min max & peak load is 2A initially, otherwise normal load is 1.5A.

2. Used Webbench for selecting right dc-dc. It retruned ( webench.ti.com/.../SD2.cgi ). Report is also attached.

I have feq queries on it:
A) What is operating temperature range of entire dc-dc. System shows it is designed for 30C ambient. But if I enter higher ambient temperatue range it fails

B) Can the webbench do PCB design in double side rather than 4 layer PCB. As double side PCB are way most cost effective than four layer.
Also while desiginig can be put some pcb size restrictions on board?

C) What is max temperature on board goes?

webench_design_4197002_10_265690303.pdf

  • 0
    TI__Mastermind 40080 points

    Hi,

    TPS61089 is just fit for   your application.

    Webench may only simulate the normal Temp condition, as it is too complex to simulate all the temperature conditions.

    Please read the datasheet carefully, this IC can support 85C ambient Temp with very good layout.

    You can use 2-layer PCB instead of the 4-layer ones. Please refer to the layout example on the datasheet.

  • 0 in reply to Helen chen
    TI__Intellectual 1020 points
    Hi Vindhyachal,

    I tried out the design for TPS61089 at this condition-

    Input: 6V-8.6V dc
    Output: 12V/2A
    Ta = 85 C

    I am sharing the design at your email.

    Also if you want to estimate max temp on board, you can run WEBENCH thermal simulation and see the values( again this you can find in the report I shared with you). You can even change copper weight, add air flow and change the copper area in WEBENCH and then run thermal sim to see temp behavior.

    WEBENCH will only not give a design for those conditions when it "calculates" that IC Tj can go above recommended max(125 C in this case) for a particular Theta J-A and the IC power dissipation that is happening at that operating condition
    However this does not mean that you can not use the design, with proper layout,etc, you can still bring the temp on board to lower limits as needed by your application

    Currently WEBENCH supports PCB design for layers which correspond to what was originally used in the EVM, so that if user wants to test the design on TI EVM with WEBENCH results, he can check that out.
    However as Helen mentioned,you can use 2 layer PCB.

    I guess you might have more questions on WEBTHERM sim ,Electrical Sim and WEBENCH design for your condition

    Feel free to drop me a mail at sahilg@ti.com and I will hold a WEBEX.

    Thanks
    sahil