• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 826 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TPS2121: TPS2121 Output capacitance calculate

Kevin.Peng
Intellectual 780 points
Part Number: TPS2121

Hi Team,

    We tried design TPS2121 need to know how much capacitance is okay to load on output?
Please help check the schematic as below figure.
1.IN1=5V (adapter input) and IN2=8V (form battery input). Current load is 4A
2. No additional OVP protection required, PR1/ OV1/ OV2/ CP2 to Ground.
3. Please check schematic if the is correct?
4. Do need to put a 400uF capacitor or other value in the output? How to calculate? thanks

Sincerely

Kevin

  • 0
    TI__Genius 10855 points

    Hi Kevin, 

    Thanks for reaching out on E2E!

    The maximum output capacitance will ultimately be dependent on the inrush current during switchover. If you have too much load capacitance, the inrush current can cause the device to enter current limit or thermal shutdown and restart. You can calculate the expected inrush current by using the equation I = Cload * dV/dT to see if this will occur.

    The easiest way to configure the output capacitance is to take a TPS2121EVM and measure the switchover from IN1 to IN2. You can measure the slew rate while the device switches from IN1 to IN2 (dV/dT), and adjust the Cload value depending on how much inrush current you are experiencing.

    Thanks,

    Arthur Huang