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TPS61045 maximum output current

Mark Brinkman
Intellectual 260 points
Other Parts Discussed in Thread: TPS61045, TPS61080, TPS61081

Looking for a single output boost transducer power supply. 5V input with firmware programmable output of 5, 10,  15 or 24V. 40mA max. output current. Was intrigued by digitally adjustable boost converter TPS61045 but based on 10uH inductor I don’t think it can supply the current at 24V output. Any thoughts or alternative parts? Does any of the TI simulation tools support this device?

thanks

Mark

  • 0
    TI__Mastermind 46905 points

    HI Mark

    yes, TPS61045 can't not supply the 24V&40mA output. we have other device which support this output power, but do you need to change your output voltage online?

    thanks

    Jasper li

  • 0 in reply to Jasper Li
    Intellectual 260 points

    Hi Jasper,

    Yes firmware adjustable output voltage is the goal. Firmware must also must be able to turn OFF the output completely i.e. I don't want the 5V input to pass thru to the output. Do you have another product that meets my needs?

    What output current can the TPS61045 deliver at 24V? I calculated around 6mA with a 10uH inductor.

    Thanks

    Mark

  • 0 in reply to Mark Brinkman
    TI__Mastermind 46905 points

    You can have a look at TPS61080 and TPS61081, The Vin also disconnect with Vout if EN is off. The device have a internal recitify diode.

    yes, my calculation result is almost the same as yours according to datasheet.

    Jasper li

     

  • 0 in reply to Mark Brinkman
    TI__Mastermind 46905 points

    hi Mark

    sorry for the mistake, the max. output current of TPS61045 should be about 23mA at 24V output. the Iout_max formula in page 11 should be (Ip*Ip*L*Vin) / (Vo-Vin)*(...), not (Ip*Ip*L*Vin)) / (Vo*Vin)* (...).

    thanks

    jasper li

  • 0 in reply to Jasper Li
    Intellectual 260 points

    Jasper,

    Thanks for the correction. With regards to firmware controlling the output voltage I guess you have no other controller options. I guess I can use an analog switch to switch in different resistor feedback networks to set my output. For 4 different output voltages I guess a 4:1 mux is in order. Any suggestions?

    thanks

    Mark

  • 0 in reply to Mark Brinkman
    TI__Mastermind 46905 points

    HI Mark

    it sound a good solution, and a similar way to set output voltage as TPS61045 is also a option.

    you can apply a EVM to verify the your idea.

    thanks

    Jasper li

  • 0 in reply to Jasper Li
    Intellectual 260 points

    Jasper,

    TPS61045 documentation. You found the equation error for I(load)(max) on page 11. Is the equation for Ip on page same page 11 correct? It is dominated by the 300mA and does not look like the same equation on page 10. Should V(in) be divided by L instead of 2?


    Thanks

    Mark

  • 0 in reply to Mark Brinkman
    TI__Mastermind 46905 points

    Hi Mark

     you are right. the V(in) should be divided by L. and equations of Ip on page 10,11 are the same. but 300mA instead of 375mA should be used to calculate the Ip at the formula of I(load)(max). because 300mA is minimum current limit considering the temperature and device variation, and 375mA is typical current limit at 25 ambient temperature.

    thanks a lot for pointing out this. we'll  modify the datasheet in next version.

    Jasper li