• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 63 subscribers
  • Views 486 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: [LM3630A] Current setting inquiry

MJ Jeon
Genius 5240 points

Part Number: LM3630A

Hi, TI Support Team

A customer is reviewing a product using the LM3630A.

Please check the inquiries below.

Q. Which of the following LED Dimming (Brightness Control) methods has the lowest current consumption?

- I2C Control

- PWM Control

- I2C + PWM Control

Please check the following inquiries regarding Brightness control.

Full scale current=20mA, BRT=0x01, Min in Exponential mapping mode described in the datasheet. Current is listed as 13uA.

Q. Does full scale current mean the maximum current of each line?

Q. Is full scale current adjustable?

Q. If full scale current of each line (LEDA, LEDB) = max. If the current is correct, is it possible to adjust the full scale current to 10mA?

Q. If possible, please tell me how to set it up

Thanks.

Regards,

MJ

  • +1
    TI__Genius 12915 points

    Hi MJ,

    Please see my feedback as below red mark.

    Q. Which of the following LED Dimming (Brightness Control) methods has the lowest current consumption?

    The power consumption for different brightness control mode should be similar. PWM mode is higher than I2C mode. But the resistance for PWM input pin is high, that current for PWM input signal is very small.

    Q. Does full scale current mean the maximum current of each line?

    The full scale current mean maximum current setting for each bank. 2 channels can be linked to different bank, to set different full current.

    Q. Is full scale current adjustable?

    Q. If full scale current of each line (LEDA, LEDB) = max. If the current is correct, is it possible to adjust the full scale current to 10mA?

    Q. If possible, please tell me how to set it up

    Yes they can be adjusted in register 0x05 and 0x06. The current range is from 5 mA to 28.5 mA.

  • 0 in reply to Hardy Wu
    Genius 5240 points

    Hi, Hardy

    Can I set the register to 0x04 to set the max current of each line to 10mA?

    Current range=23.5mA

    setting current=10mA

    default min. current=5mA

    5mA=23.5x0.21

    max current setting register value: 0x1F

    0x1f/4 (0.25%)=10.875 mA

    If you look at the calculated value, it is calculated as max current=10.875mA when it is set to 0x04.

    Please confirm that it is correct.

    Thanks.

    Regards,

    MJ

  • +1 in reply to MJ Jeon
    TI__Genius 12915 points

    Hi MJ,

    You could refer to datasheet section 7.3.1.11. You could set the value to 0x06 or 0x07.

  • 0 in reply to Hardy Wu
    Genius 5240 points

    Hi, Hardy

    I have a question during the test.

    I am testing by applying exponential MAPPING MODE.

    Measurement was performed by changing the value of the Full Scale LED Current register.

    However, as shown below, the max brightness in LED_Bank A is not working properly, so I would like to ask.

    LED_Bank A (COOL LED) Number of SERIAL LEDs: 12

    LED_Bank B (WARM LED) Number of SERIAL LEDs: 11

    What causes LED_Bank A not to work properly?

    If there is anything that needs confirmation, please reply.

    As a reference, the spec of the LED under test is added.

    Thanks.

    Regards,

    MJ

  • 0 in reply to MJ Jeon
    TI__Genius 12915 points

    Hi MJ,

    Some tests need to be done on EVM but I am out of office this week and will reply you in the early next week. Sorry for the late.

  • 0 in reply to Hardy Wu
    Genius 5240 points

    Hi, Hardy

    When can I get a reply?

    Please confirm.

    Thanks.

    Regards,

    MJ