• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 198 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.

TLV62568A: How much load capacitance is support

yongfei qu
Prodigy 50 points
Part Number: TLV62568A
Other Parts Discussed in Thread: TPS628511, TPS628301, TPS628501

Tool/software:

In my design, input voltage is 5V, output is 3.3v, INDUCTOR is 2.2uh, load capacitance is 200uf(include output capacitor for dc/dc and decoupling capacitor for other digital IC).

Table 4 in the datasheet shows the range of output capacitor is 22 μF to 47 μF.

Q:

Does TLV62568A support large load capacitance(up to 200uf)?

Does larger load capacitance cause instability?

  • 0
    TI__Mastermind 21580 points

    Hi Yongfei,

    The TLV62568A won't be able to support more than 47uF output cap. Higher output cap causes the control loop to be unstable. Please use TPS628511, TPS628501 or TPS628301 to support larger output caps. 

    Best regards,

    Varun

  • 0 in reply to Varun John
    Prodigy 50 points

    Hi Varun.

    For stable operation, does output capacitance must have a minimum ESR value？

    if 47uF or less  output cap. directly at the output of the device TLV62568A, Is More capacitance allowed if there is a series resistance associated to the
    capacitors? 

    Best regards,

    Yongfei Qu

  • 0 in reply to yongfei qu
    TI__Mastermind 21580 points

    Hi Yongfei,

    Unfortunately this won't help as there is already an internal compensation zero. Adding another one externally via the series resistor to the cap can end up making the loop unstable.

    What you can try is, adding a second inductor/ferrite bead between the 47uF close to the IC and the rest of the bulk caps at the point of load. The inductor/ferrite bead can help reduce the effect of the bulk caps on the control loop. The output for the FB network should be tapped from the local caps before the 2nd inductor/ferrite bead. You would need to run some Bode measurements to verify a good phase margin with this approach.

    Best regards,

    Varun