• RE: LTC4121-4.2 charging current issue

    I feel like this could be layout related. I know that the LTC4121 is sensitive to VIN cap location. Could you share your board layout screenshots, especially the portion that shows the loop of CIN_TOP-IC-GND, and also the loop of C_INTVCC-IC-GND? 


  • LTC4121-4.2 FAULT indicator


    Kindly list the conditions the FAULT pin is asserted.

    I have implemented the reference design (MPPT/RUN/400mA) and I noticed the strogger the power surce is (12V/1A wall cube), the less energy is delivered to the battery because FAULT is asserted…

  • LTC4121: battery disconnection

    Good morning,

    I'm using LTC4121 in my system in order to recharge a single-cell Li-Ion battery. 

    In order to prevent excessive heating, I'm using the NTC pin in order to pause the recharging process when the temperature reached is 50°C.


  • LTC4121 with input voltage regulation feature disabled?

    On page 8 of the LTC4121 datasheet, the description of the MPPT pin states that

    If the input voltage regulation feature is not used, connect MPPT to either INTVCC or IN with a minimum 10k resistor.

    What is the expected charging behavior when "input…

  • My LTC4121 circuit is not charging the Li-Ion battery

    I laid out the circuit as close as possible to the evaluation board. The circuit would charge intermittently well below the programmed current and eventually stopped charging completely well below the FB resistor programmed float voltage. I bought the…

  • LTC4121 is not charging


    I am currently working on a LTC4121 for the 3-Cell Li-Po solar charging. I have made my printed circuit board to test this solar charging, and I found out that it's very hard to make this chip working.

    I have tried to make my first PCB without…

  • LTC4121 Not Charging at Lower Panel Voltages

    Hi All,

    I am having an issue with a design using the LTC4121. The panels I am using have the following specs:

    • Typical voltage: 5.5V
    • Typical current: 170mA
    • Open-circuit voltage: 8.2 V
    • Maximum load voltage: 6.4V

    The LTC4121 is being used to charge a LiFePO4…

  • RE: LTC4121-4.2 model

    I'm sorry to report that we have no simulation model for the LTC4121/LTC4121-4.2.  I can provide applications support for the part if that would be helpful.

  • LTC4121 as a solar charger for supercaps?

    Hi there,

    I was just wondering if it is possible to use the LTC4121 as a solar charger for supercaps?

    In my application I like to support both Li-Ion XOR supercap charging. (Little circuit modfications are ok)



  • Difference between DC1977A-A and DC1977A-B

    What is the difference between DC1977A-A and DC1977A-B?

    They both list LTC4121 and LTC41421-4.2V.
    Same Vin range 4V to 40V.
    And charging current 400mA.