• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 126 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.

LM3630A: 3630A restart issue

Vayne Li
Intellectual 980 points
Part Number: LM3630A

Tool/software:

Hi Tams,

The customer's product is an e-book, and they use LM3630A as the backlight driver.There is a problem now and I would like to ask TI for help.

3630A restarts with the front light turned on, there is a probability that the front light will not light up after restarting. Reset(Adjust the brightness of the lower light, or turn on and off the lower light) the front light brightness to normal.

Equivalent to calling this,

The customer suspects that it is caused by OVP, but according to the datasheet, OVP will self recover.
So they tested the waveform,

Blue is the OVP pin of the chip and the positive pole of the lamp. The yellow is the interrupt pin of the chip, and the OVP pin did not have such a large overshoot when the first light was turned on during restart,

Turn off the light and then turn it back on, there will be a 37V overshoot.

  • 0
    Intellectual 980 points

    Hi Teams,

    I would like to add a schematic diagram here. Could you please help me take a look at this issue? Thank you!

  • 0 in reply to Vayne Li
    TI__Expert 6680 points

    Hi Vayne,

    I don't quite get your description of the issue. And looking at the schematic, do you know why LED1- and LED2- are connected to the output of the LED driver instead of LED+? I suppose LED+ is the anode of the LED string and LED- is the cathode of the LED string. Can you confirm?

    Regards,

    Hongjia

  • 0 in reply to Hongjia-Wu
    Intellectual 980 points

    Hi Hongjia,

    Thank you for your reply,On the right side of the schematic is the socket,the schematic only changed the pin connections, not the socket description.

    Can you give me an email address? I can describe it to you in Chinese.

    The customer has confirmed that it may be a problem with the driver. The 0x00 register was not set during initialization, which may result in being set in sleep mode, i2c_smbus_write_byte_data(LM3630Aclient, REG_CTRL, 0x06); //cold,

    Only when setting the brightness, set the 0x06 register.. Is there a need for a delay at this point? Without a delay, they checked and found out that REG_SRT_S is not updating.So they modified i2c_stmbus_frite_byte_data (LM3630AClient, REG_CTRL, 0x06); //Cold arrived early for the probe.

  • 0 in reply to Vayne Li
    TI__Expert 6680 points

    Hi Vayne, please find my email address as hongjia-wu@ti.com. I will close the thread here. We can discuss over email.