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TPS65012: Please help me select the right PMIC for our product

John Thompson63
Prodigy 190 points
Part Number: TPS65012
Other Parts Discussed in Thread: TPS65721

Hello, 

I'm trying to find a PMIC that's easy to use, low-cost, and has minimum component count.

Requirements:

  • Lithium-Ion-polymer battery charging circuit (4.2V, 125mA max charge current).
  • Switching voltage regulator (Buck/Boost) (4.2V to 3.3V) 95% or greater.
  • (Bonus) fuel gauge or someone to monitor battery life (uC ADCs are 3.3V tolerant).

I'm currently looking at the TPS65012, but it's way too overkill for our application.

Thank you in advance for any suggestions you can give!

John

  • 0
    TI__Intellectual 1020 points
    Hello, thank you for posting your question on the TPS65012 in the e2e forum.
    Your thread has been assigned to the expert within TI, who will reply to your question as soon as possible and attempt to resolve your issue.

    Regards.
  • 0
    TI__Genius 10885 points
    Hi John,

    The TPS65721 might be a good fit, it's a simple PMIC with adjustable charge current and versatile regulators, but it does not have a boost regulator or fuel gauge.

    Best Regards,
    Rick S.
  • 0 in reply to Richard Solarski
    Prodigy 190 points

    Rick,

    This is very close to what I need.

    Anything with a smaller solution size? 

    The recommended layout shows 13 external resistors and capacitors. Not really a "small solution size" in my mind.

    My current design is using MCP73831T-2ACI/OT(charger) and TPS63001DRCR(Buck/Boost) with only 8 external components. So I'd like to essentially replace these items with a simpler, more compact solution.

    John

  • 0 in reply to John Thompson63
    Prodigy 190 points

    Hi Rick,

    Please help with a minimum component build using the TPS65721.

    This is what I'll be using it for:

    • Lipo Battery charger for 240mAh battery
    • 3.7V to 3.3V regulation for 3.3V IC (what happens when the input goes below 3.3V?)
    • Using the LDO (@3.3V) to power LED strand. (can this be turned on and off?)
    • GPIO 0: current sink for voltage divider to convert 4.2V lipo battery voltage to measurable 3.3V
    • GPIO 1: current sink for voltage divider to create 1V external analog reference.

    I'll post my circuit diagram if I get farther than you over the weekend for your review. 

    If the IC works out, we'll be using it in our product! ;)

    Thank you for all the help!!

    John

  • 0 in reply to John Thompson63
    TI__Genius 10885 points
    Hi John,

    We would still recommend those external components for proper operation, but I'm looping in an engineer more familiar with the TPS65721 just in case.

    The buck regulator should operate down to 100% duty cycle and shutoff once VIN is below UVLO. The LDO can be enabled and disabled via HOLD_LDO1.


    Best Regards,
    Rick S.
  • 0 in reply to Richard Solarski
    Prodigy 190 points

    Hi Rick, 

    I think I decided that just a low-dropout regulator (LDO) would better meet my needs. 

    (1) The efficiency of an LDO is acceptable for a 3.7V - 3.3V drop (89%).

    (2) The footprint required for the TPS65721 is just too large for me. LDO only requires two bypass caps.

    (3) I'm worried about the EMI generated by the switching regulator will slow us from achieving FCC mark. 

    I'll be starting another conversation on the linear regulator forum. 

    Thanks for your help!

    John

  • 0 in reply to Richard Solarski
    TI__Genius 9380 points

    John,

      Ricks statements are correct. There is no way to reduce component count unless you can live with fixed voltages. In the image below you have a few options. If you choose a fixed voltage you can remove two resistors and a filter cap for the feedback circuit on that rail.

    Finding a buck/boost with a charger is nearly impossible. there are several buck/boost chargers but they typically don't have the regulator internal.