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TPS780: pin selectable output LDO

Ella KIM
Expert 3962 points
Part Number: TPS780
Other Parts Discussed in Thread: TPS62840, , TPS7A94, TPS7A02, TPS7A57, TPS7A85A, TPS7A84A, TPS7A83A

Hi LDO folk,

 There would be three types of LDO devices ; fixed output, adjustable output, VSET type output. I wonder if TI has device with VSET type like TPS62840. TPS62840 has internal resistor to digital converter to determine the output voltage by only one resistor. Customer wants to reduce FB resistors in LDO.

TPS62840 1.8-V to 6.5-V, 750-mA, 60-nA IQ Step-Down Converter datasheet (Rev. D) (ti.com)

Question 1.

I notice TPS780 has internal EPROM to control the output voltage level. But this device is applicant only for a specific MCU application and its current rating is too low for my customer. Do we have another LDO device with VSET pin and the higher current rating?

Question 2. 

Customer has a concern on internal EPROM because it will be clocking and it can be an noise source in system level. Can you share your thought on this concern?

Question 3. 

Due to the concern in Question 2, customer prefers integrated ADC like TPS62840. Do we have this type of LDO?

Thank you!

  • 0
    TI__Mastermind 18466 points

    Hey Ella, 

    I will look into this for you. 

    Best,

    Juliette

  • 0 in reply to Juliette
    TI__Expert 3962 points

    Hi Juliette,

    When can I expect to hear from you? Thank you.

  • 0 in reply to Ella KIM
    TI__Mastermind 18466 points

    Hi Ella, 

    I am waiting for one more response, I will get back to you with more detail tomorrow.

    Best,

    Juliette 

  • +1 in reply to Juliette
    TI__Mastermind 18466 points

    Hi Ella, 

    Question 1

    I notice TPS780 has internal EPROM to control the output voltage level. But this device is applicant only for a specific MCU application and its current rating is too low for my customer. Do we have another LDO device with VSET pin and the higher current rating?

    >>>

    Because we do not know how much current your solution needs, it is difficult to point to a specific device. 

    - TPS7A94, 1A current, lowest noise on the market, but it has a higher Iq

    - For ultra low Iq we have TPS7A02 but that is just 200mA

    - TPS7A57 is currently being worked on and the device is similar to the TPS7A94 in that you can set the output through an external resistor, but you would have to email Xavier Ramus for more information on that part (RTM, SPECS, ETC)

    - TPS7A83A, TPS7A84A, TPS7A85A as well since they also have the programmable output/ANYOUT feature

    - Another option is to parallel low Iq LDO’s to give more current and maintain the low Iq

    Question 2

    Customer has a concern on internal EPROM because it will be clocking and it can be an noise source in system level. Can you share your thought on this concern?

    >>>

    Going with a fixed output version may be beneficial in reducing the overall noise because there would be less components, for noise to couple through,  included in the BOM of your application. 

    The TPS780 is an older device (2007) and our newer devices should have better noise performance.  Figure 40 in the TPS780 datasheet provides the output spectral noise density of the device. 

    Question 3. 

    Due to the concern in Question 2, customer prefers integrated ADC like TPS62840. Do we have this type of LDO?

    >>>

    Keith Kunz helped write this White Paper that helps address the concerns/rational behind the integrated ADC. Integrated ADCs are mainly done to decrease the Iq, and not necessarily to reduce noise (see page 12).

    Best, 

    Juliette

  • 0 in reply to Juliette
    TI__Expert 3962 points

    Hi Juliette,

    Thank you for your response. It's so helpful. 

    Just out of curiosity, from your response 3, TI does not have any LDO device with R2D type with integrated ADC. May I know why? R2D type would help for the low Iq design according to the white paper.

  • 0 in reply to Ella KIM
    TI__Mastermind 18466 points

    Hey Ella, 

    I am not the best resource for this question, but I have reached out to colleagues that may be better suited to answer this question. I will update you with a response. 

    Best,

    Juliette

  • 0 in reply to Ella KIM
    TI__Expert 5251 points

    Hey Ella, 

    Thank you for the input. We currently do not have any R2D type devices.