• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 527 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.

TPS65235-1: About Cboost capacitor

Hide
Guru 21045 points
Part Number: TPS65235-1

Hi Team,

 

Our customer use “3 x 10uF(Rating 25V)” of the boost capacitor at the following conditions.

We understand that the recommended rating of the boost capacitor is 35V.

However, they would like to use this capacitor to drive down the BOM cost.

 

[Conditions]

VIN=12V

VOUT=11V(min)/19.5V(max)

ILOAD=around 300mA (current limit is 600mA)

FSW=500kHz

L=10uH

CBOOST = 3 x 10uF(Rating 25V)* for the boost capacitor.

 

The effective capacity of this capacitor is 4.775uF at around 20V.

(So, total effective capacity is 14.325uF (4.775uF x 3))

I guess that TPS65235-1 can stably operate.

However, could you please let us know if you have any concern?

 

If you contact to below my e-mail address or let me know your e-mail address,

I can send the customer information.

I’m looking forward to hearing from you.

 

[my e-mail address]

Kanemaru-h@clv.macnica.co.jp

 

Regards,

Kanemaru

  • 0
    TI__Genius 15135 points

    Hi,

    My Email is zhao-ma@ti.com

    If your description is true, i think the TPS65235-1 can stably operate.

    But are you sure about this: The effective capacity of this capacitor is 4.775uF at around 20V.

    According to our before test result, as for 22uF/35V capacitor, when bias DC 20V, the actual capacitance is only ~5uF.

    Generally speaking, the higher rating voltage, the capacitance degrading will be small, so we suggest to use 35V rating capacitor.

    Besides stability, i think the small boost cap will lead to VLNB output ripple become bigger.