• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 65 subscribers
  • Views 250 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TPS61299: Question about Vsel pin configuration

Chase Jeong
Genius 5450 points
Part Number: TPS61299
Other Parts Discussed in Thread: TPS61094

Dear TI experts,

My customer considers TPS61299 for their new product.

I saw the table 7-1 on the datasheet, about Vsel pin configuration.

- 191Kohm for 2.5V output,

- 237Kohm for 2.2V output.

Could you confirm that if I set 200Kohm for Vsel pin?

I am asking it because I thought that I can see the output voltage between 2.5V and 2.2V if I set 200Kohm (probably near 2.5V..)

but my customer said that sometimes they see the output which is very abnormal, even cannot see any voltage.

then what should we do if we need a voltage like 2.4V or 2.3V?

please check this issue. Thanks.

Best regards,

Chase

  • 0
    TI__Expert 5475 points

    Hi ,

    TPS61299 selects the internal Vref during start up. Without a recommended Rsel , the device cannot work. The device does not support 2.3V or 2.4V Vout. If you have to use 2.4V, maybe you can connect a LDO on the output(but suffers more loss), or you can see TPS61094.

    Best Regards,

    Travis

  • 0
    TI__Expert 7925 points

    Hi Chase, 

    you could choose either 2.2V or 2.5V,. There is no output voltage between 2.2V and 2.5V. 1% tolerance is acceptable, if you set 200kohms, output is set to 2.5V.

  • 0 in reply to Nini Zhong
    Genius 5450 points

    Dear Travis, Nini,

    Thank you for your support.

    My customer said that if they disconnect VIN and connect IN right away, output does not detected.

    (they use same voltage for VIN and EN, and about 0.3V is detected when they disconnect VIN.)

    Is there minimum time that can operate the device properly between power down and power on?

    I attach a schematic for your convenience.

    Best regards,

    Chase

  • +1 in reply to Chase Jeong
    TI__Expert 7925 points

    Hi Chase, 

    I didn't get your meaning of disconnecting IN and VIN? Do you mean EN and Vbat  ? Have you test the voltage of EN pin? Why do you use 10Mohms resistor?

  • 0 in reply to Nini Zhong
    Genius 5450 points

    Dear Nini,

    Thank you for your support.

    There was a typo on my previous post. (My customer said that if they disconnect VIN and connect VIN right away...)

    Now they use power supply for the test, so they can connect and disconnect VIN as they want.

    voltage of EN is fine, they used 10Mohm for low current consumption. (it is the application which is working with very small battery.)

    What I want to know is that if we disconnect VIN and apply VIN again right away, it is not working. (output is not detected.) Is it normal operation?

    If yes, what is the minimum time of disconnecting and connecting of VIN for normal operation?

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Expert 5475 points

    Hi Chase,

    I think the device is working normally.

    The minimum time of disconnecting will depends on the capacitance of Cin and your inductor current IL. The Cin will be discharged by IL until Vin drops below UVLO threshold or EN.

    And, the 10M resistor is totally unnecessary. This is not a pull-up circuit. Placing a resistor will not reduce the leakage current.

    Best Regards,

    Travis