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TLV61224DCKR can output at least 40mA current stably from a 1.5V?

Vicky Lin
Prodigy 10 points
Other Parts Discussed in Thread: TLV61224

We design in TLV61224DCKR and has the serious unstablity issue.
Need TI's kind support for the following questions
1. Does TLV61224DCKR require "Minimum Load Current Operation" ?
2. The information described in datasheet is "Output Current of More Than 40 mA From a 1.2-V" but also mentioned "only 15mA output current from 3V power supply" as shown in the following picture that confusing us.  
May we know how to make sure TLV61224DCKR can output at least 40mA current stably from a 1.5V?

  • 0
    TI__Genius 9046 points

    Hi Vicky,

    There is no requirement for minimum load. Because the IC limit input current from overload, so the lower Vin, the lower output current for 3.0V output.

    The datasheet described it can output 40mA at minimum input of 1.2V. In Figure 8, minimum input voltage now becomes 0.8V, so maximum output current becomes less.

    For Vin=1.5V, typically TLV61224 can output about 70mA current, but in the worst case where current limit is 160mA, the maximum output current will be about 30mA.

    Could i know how TLV61224 is used in your application? What is the schedule and volume? 

    -Wenhao

  • 0 in reply to Wenhao Wu
    Prodigy 30 points

    Hi,

        Our application is a simple BLE tag with TLV61224 to supply power for BLE chip Nordic nRF52832 from 1 cell battery.

    We use the reference circuit provided in the datasheet as shown above with the following issues in first 5000pcs mass-production.

    1. Defect rate : ~ 20%

    2. The output voltage is not fixed at 3.0v but falls below 1.5v.

    3. If we tried to put a diode between TLV61224 output and nRF52832 Power input, the issues improve but not all.

    4. If we tried to put a resistor in series between TLV61224 output and nRF52832 Power input, the issues improve but not all.

    5. If we tried to replace the 4.7uH (w DCR 145m ohm) with 47uH (w DCR 60m ohm), the issues improve but not all.

    May we have your kind comment for the issues.

    - Yujen

  • 0 in reply to YuJen Yang
    TI__Genius 9046 points

    Hi Yujen

    As what I have said, in the worse case the maximum output current can only reach to 30mA because of current limit variations. and this maximum output current would also reduce if you have higher operating temperature as efficiency in that case drops.

    There though exists another possibility which can lead to output drop. The layout can be a cause which leads to noise to the control loop, so output becomes unstable.  Please share the schematic and layout to me for review.

    Again, 40mA is what is already marginal for TLV61224 which we cannot promise it would not reach to current limit.

    -Wenhao

  • 0 in reply to Wenhao Wu
    Prodigy 30 points

    Hi Wenhao :

       Thanks for your quick reply.

    Do you mean the issues are caused by overloading ?

    If yes, BLE chip nRF52832 is very low power consumption with less than 20mA in maximum TX power mode.

    It should be safely under the limitation of worst-case 30mA maximum output current, especially we are testing with 1.5v input.

    Any comment ?

    thanks again.

    -Yujen

  • 0 in reply to YuJen Yang
    TI__Genius 9046 points

    Hi Yujen,

    It may caused by over loading or bad layout. If you rise input voltage to for example 2V and output voltage did not cover, it could be layout which cause this issue.

    -Wenhao

  • 0 in reply to Wenhao Wu
    Prodigy 30 points

    Hi Wenhao : 

        Thanks for you great comment.

    We will give it a trial and then feedback to you later.

    - Yujen

  • 0 in reply to YuJen Yang
    TI__Genius 9046 points

    Hi Yujen,

    Would you please share the layout also?

    -Wenhao