• LTC4040


    I have a problem with my LTC4040 schematic. Vsys voltage is 4.8V. Schematic work in buck and boost mode , with / without Vin. The problem is charging. The battery is not possible to charge above 2.8V.  Charging stop when the battery voltage become…

  • LTC4040 Charging problem

    Hi all,

    i have an LTC4040 used in my project but i have a problem.

    I use 18650 Li-Ion Battery connected to LTC4040. Signals F0,F1,F2 are all at 5V to select Li-Ion and 4,1V according to datasheet. Input PFI divider is used 174k/60k4 for about 4,6V detection…

  • LTC4040 - Undervoltage Lockout

    Per the datasheet:

    "To prevent the battery from discharging too deeply, the LTC4040 incorporates an undervoltage lockout circuit which shuts down the boost regulator when VBAT drops below 2.45V. "

    I would like to prevent the battery from discharging…

  • LTC4040 Vsys voltage when shutdown (BSTOFF , CHGOFF = 1)

    Hello , I use LTC4040 to make 5 V UPS project.  Vsys voltage when shutdown LTC4040 (BSTOFF and CHGOFF = 1) is about 3.7 v. My battery is Li-Ion 4.1 volt type and voltage is 3.9 V.

    Is it normal? I understand that Vsys should be 0 V when shutdown LTC4040…

  • Life-cycle status of the LTC4040...


    What is the life-cycle stats of the LTC4040 battery manager?  Is it Active, Obsolete, Not Recommended, ...?  If it is active, how close is it to End of Life?

    Thanks, and

    Best regards.


  • Current problem in LTC4040 backup mode

    Prepare to use the LTC4040 3.7V lithium-ion battery as a backup power supply. During the test, the charging process was found to be normal. However, in the backup mode (the output voltage adjustment resistor is adjusted to 5V and the battery voltage is…

  • LTC4040备份模式下提供电流大小

    在产品中准备使用LTC4040 3.7V锂离子电池作为后备电源,试验过程中,发现充电过程正常,但在备份模式下(输出电压调整电阻调整为5V,电池电压3.7V时),只能提供800mA的电流,可能的原因是什么?(试验时,用的5Ω电阻作为负载,显示负载两端电压为4.1V)

  • LTC4040: Battery charge current < 500mA?

    The datasheet describes setting the battery charger current using a resistor from PROG to ground.  It is also stated;  "The minimum
    recommended charge current is 500mA, below which the accuracy of the charge current suffers. This corresponds to a maximum…

  • LTC4040: Charger waveforms (low freq SW)?


    I have my LTC4040 configured with 500mA charger current.  Inductor is 22uH (XAL-5030-222).  Capacitor in parallel with battery = 10uF

    As the battery is charged and the charger current drops to ~200mA, I am seeing a low frequency (115KHz) ripple on the…

  • LTC4040 - What does "Kelvin the top of the resistor dividers to the positive terminal of CSYS." mean?


    LTC4040 Datasheet, Page 23, Section 4. says

    "Kelvin the top of the resistor dividers to the positive terminal of CSYS."

    What does Kelvin mean in this context?

    Thanks in Advance!