Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 64 subscribers
  • Views 313 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TPS65142: Using the boost converter without dimming control?

Thomas Middleton
Prodigy 10 points
Part Number: TPS65142
Other Parts Discussed in Thread: TPS65150

In my application, the LED back light we have I don't think can be controlled with the integrated dimmer. It is a single Anode/Cathode for the LED array and has an IF of 180mA nominal.

I want to know if I can leave the pins DCTRL, EN, VBAT, VO, IFFBn, and ISET floating in this application. From the datasheet (shown below) the diagram (7.2 Functional Block Diagram) seems to indicate these pins as functionally isolated from the other supplies. I assume the PGND and AGND are still necessary connections.

Alternately, I was wondering if this could be used for my application. i.e. can the IFB be ganged together somehow to get a higher current capability? The LEDs I'm driving have a VF of 8.4 to 10.8 (9.6 nominal) and IF of 180mA (nominal). Additionally, can the WLED boost control be used independent of the dimming control? such that I could power the LEDs but control dimming in a different way.

Regards,

Tom

  • 0
    TI__Mastermind 18550 points

    Hello Tom,

    Thank you for your post. I am a bit busy with some customer issues ahead of this one but should be able to review TPS65142 datasheet/application information to answer you query by Thursday June 10th if not earlier. Thank you for your patience and understanding.

    Kind Regards,

    Liaqat

  • 0
    TI__Mastermind 18550 points

    Hi Tom,

    Thank you for your patience. I reviewed TPS65142 datasheet and application information. If you do not want to use the backlight driver of this device, I suggest to connect pins as follows: EN, DCTRL = GND, VBAT = VIN, VO, ISET, IFBn = floating, AGND,PGND = GND.

    I could not find any information that suggest whether IFBn can be ganged together to achieve higher single string current but I strongly suspect that this can be done because because I have tested other backlight driver in the past and they all allowed for current sinks to ganged together to achieve higher string current. One simply shorts enough IFBn channels to achieve the desired current. Unfortunately, I could not locate an EVM for this device to verify this kind of operation on it.

    One more important point is that the backlight driver boost can not regulate to a voltage below 15V (see section 7.3.9 WLED Boost Regulator) and you mentioned that your LED string VF is as low as 8.4V.

    If you decide not to use the backlight driver in this device, I suggest to use a simpler LCD bias only device such as TPS65150 instead of this TPS65142.

    I hope that this information is helpful.

    Kind Regards,

    Liaqat