• State Resolved
  • Locked Locked
  • Replies 11 replies
  • Answers 1 answer
  • Subscribers 40 subscribers
  • Views 2895 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Boost solutions with WEBENCH (2x AA-batteries to 5V )

Wasya Kuznetsov
Prodigy 65 points
Other Parts Discussed in Thread: TPS63000, TPS61032, TPS61030EVM-208, TPS61020, TPS61030

Hello!

In early 2015 I created a project with an boost of 1.8-4V input voltage to 5V and current of 1A (http://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=204C5986C0CB0837   TPS63000).
Now, with the same input data Webench does not find any solutions. Maximum what possible - 0.6 Amperes (http://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=B3DBA6AEF987D036 TPS 63020).
1) Could you clarify the reason for the exception of the first solution from Webench?
2) Is there a working solution from TI for this kind of power scheme with the current up to 1 A?

Thanks in advance!

 

  • 0
    TI__Mastermind 39210 points
    Hi Wasya,

    I am not sure how you got the design using TPS63000 earlier. The limiting factor here is the current limit of 1.2A. Since you are operating in Boost mode with Iout of 1A and worst case step up of 5V/1.8V, the input current needed is 1A * 5V/1.8V * Efficiency. Even if we consider 100% efficiency, the input current needed in his case exceeds the current limit.

    Can you share the design PDF from your design in early 2015? This will help us investigate what happened with that design.

    Thanks,
  • 0 in reply to Nikhil Gupta (Product Folder Models)
    TI__Mastermind 39210 points
    I see that you have shared your design already (thanks for doing this). I think your design from 2015 was using a different backend code for this device. The original set of design equations might have had a big in them because of which you got that design in early 2015.

    In late 2015, we reworked this device calculations in WEBENCH and added electrical and thermal simulation capabilities to this device along with PCB export. The latest design constraints (current limit) seem to be accurate and you should not get a design with TPS63000 with these conditions. Apologies for the inconvenience.
  • 0 in reply to Nikhil Gupta (Product Folder Models)
    Prodigy 65 points
    Thanks for the answer.
    Unfortunately, I have realized this project and it does not work with 1.8 input voltage. So new Webench calculation is more more accurate, as you said.

    But now i can't understand why TPS61032 not proposed by Webench Design? According to the datasheet (fig2 and section 4) it is suitable for my task.
  • 0 in reply to Wasya Kuznetsov
    TI__Mastermind 39210 points
    Wasya,

    We are looking into your TPS61032 question. We will get back as soon as we have evaluated it.

    Thanks
  • 0 in reply to Nikhil Gupta (Product Folder Models)
    TI__Prodigy 540 points

    Dear Wasya,

    Thanks for using WEBENCH. The TPS61032 device has a peak current limit. This means that the device operates safely as long as the inductor's peak current is below the switch curent limit. For your given design (Vin=1.8, Vout=5, Iout=1), the inductor's peak current (IL_Avg+Di/2) is exceeding the device's max switch current limit. Please read Pg.10, section 10.3.1 of the same datasheet for detailed information.

    To be able to use TPS61032 device for your application, please either reduce the load current (Iout <= 0.5A), or operate at higher Vin (Vin >=2.5V). Should you have any other question, please let me know.

    Thanks,

    Hadi

     

  • 0 in reply to Hadi Ebrahimi
    Prodigy 65 points
    This means that there is an errors in the datasheet and TPS61032 page?
    - Section 1. 96% Efficient Synchronous Boost Converter With 1000-mA Output Current From 1.8-V Input
    - Section 3. It provides high efficient power conversion and is capable of delivering output currents up to 1 A at 5 V at a supply voltage down to 1.8 V.
    - Section 4. Why there is "5 V up to 1000 mA"? not 0.5 A? with 1.8-5V input
    - Figure 7. TPS61032 Io=1000mA with 1.8V input with 78% Efficiency
    - Section 11.2.2.3. For example, for an output current of 1000 mA at 5 V, at least 3500 mA of average current flows through the inductor at a minimum input voltage of 1.8 V.
    - Table 2. Design example with 2A(!) output.
    e.t.c

    I ordered Design Kit TPS61030EVM-208 for clarify is it suitable for my task. Now I afraid to use solution and get not working circuit board, again.
  • 0 in reply to Wasya Kuznetsov
    TI__Mastermind 39210 points

    Wasya,

    The EVM board has been tested out and should work. We are investigating further why this is not working in WEBENCH. We will get back to you shortly.

    Thanks

  • 0 in reply to Nikhil Gupta (Product Folder Models)
    TI__Genius 17905 points
    Wasya,

    The datasheet does present Vin=1.8V, Vout=5V, with Iout=1A as a working condition for the TPS61032, but this assertion assumes the typical switch peak current limit of 4A. Figure 2 in the datasheet is also based on the typical 4A current limit (this is a Typical Characteristics section).

    However, in WEBENCH, we stay on the conservative side by using the minimum switch peak current limit of 3.6A (see p. 5 of the datasheet) for the design calculations and checks. Repeating what you quoted earlier from the datasheet, >3.5A of average current will flow in the inductor for Vin=1.8V Vout=5V at Iout=1A. After adding the inductor current ripple to that, the peak current limit of 3.6A limit is violated.

    When you get your EVM and test it, there’s a good chance that you will be able to measure close to 1A output with Vin=1.8V and Vout=5V, because the particular TPS61032 IC on your EVM may have a typical or higher-than-typical current limit of >4A. But please keep in mind that another EVM with a different TPS61032 IC with slightly lower current limit or slightly lower inductor value due to tolerance may hit the current limit at a lower output current and not regulate properly at full 1A load.

    These tolerance considerations are why we prefer to err on the side of caution in WEBENCH design tools. After testing out the TPS61032 operating space limits in WEBENCH, I see that up to Iout≈0.85A is allowed in WEBENCH at Vin=1.8V and Vout=5V. Alternatively, Iout=1A at Vout=5V is also allowed with a slightly higher Vin of 2V.

    Regards,
    Kris
  • 0 in reply to Kris F
    Prodigy 65 points

    Thanks for the detailed explanation.

  • 0 in reply to Kris F
    Prodigy 65 points

    I finally receive TPS61030EVM-208 kit, and test it at normal temp.

    1.

    I set 10 Ohm resistive load at 5V output (500 mA)

    start-up only at 2.4V in and higher. 1.22A input current

    when i set input voltage at 2.2 - output 4.57V only, but input current still 1.22A

    1.8 input -> 1.84V output, 0.28A

    2. 

    Then I set 20 Ohm resistive load at 5V output (250 mA)

    start-up only at 2.2V in and higher. 0.63A input current

    1.8 input -> 2.4V output, 0.24A

    3. increased load to 1A (5 Ohm)

    I get 4.9V max output at 4.5v input, and input current 1.25A

    when i set input voltage at 2.2 - output 3.2V only, input current 1.24A

    when i set input voltage at 4.4 - output 4.87V only, input current 1.26A

    1.8 input -> 1.84V output, 0.28A

    P.S. if i set 4.5V input voltage, 1A load power on board i get 4.9V output. Then smoothly reduce input voltage to 2.9v i get max input current  equal 3.2A and then at 2.8v input, output drops to 3.7V and input current drops to 1.24A

    Result

    This solution is not suitable for me and can't start up at 1.8v input even at 250mA load. I'm very disappointed. 

  • 0 in reply to Wasya Kuznetsov
    TI__Mastermind 46905 points
    this device has soft start up feature, which means it will limit its output current during the startup. so heavy load should be only applied after the device finish its startup.
    refer to this link "www.ti.com/.../slva387.pdf" about the soft start feature about TPS61020, similar behavior in TPS61030.