• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 3 answers
  • Subscribers 63 subscribers
  • Views 488 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.

Original question:

LM3644: Asking for the recommendation on LM3644 design questions

LM3644: LM3644/LM3560 PWM controls

Patty Chuang
Intellectual 1155 points
Part Number: LM3644
Other Parts Discussed in Thread: LM3560,

More three questions about LM3644/LM3560 PWM controls.

 

1. Could you help to describe how to change PWM dynamically ?

2. What's the bit of resolution and method of PWM?Ex: linearity 8bit for 1.5A.

3. What's accuracy for the driving current? I knew there would be a challenge under low current.

  • 0
    TI__Mastermind 22745 points

    Hi Patty,

        1. I don't understand what is your meaning about change PWM dynamically.

        2. 7 bit for 1.5A

        3. We only have the spec for flash 1.5A, the varivation range is +/-7%. for torch  89.3mA, the varivation is +/-10%. Please refer to spec table 7.5.

    Regards

    Sean

  • 0 in reply to Sean Zhou
    TI__Intellectual 1155 points

    Hi Sean,

    Could you please also provide LM3560 information based on above questions? thanks!

    Regards,

    Patty

  • 0 in reply to Patty Chuang
    TI__Mastermind 22745 points

    Patty,

          For accuracy, please refer to datasheet page 5, the spec table 6.5 has given out the detailed specs. for the resolution, it is 4 bits for flash current and 3 bits for torch current. You can refer to Table 12 and Table 13. I suggest checking datasheet first before asking on E2E since all specs have already been listed on the datasheet.

    Regards

    Sean

  • 0 in reply to Sean Zhou
    TI__Intellectual 1155 points

    Hi Sean,

    still have some questions here:

    1. what i mentioned to change PWM dynamically is that is it possible to change my PWM duty? For example, If we set up torch mode as 100mA as 100% duty on first frame, we can set to 50mA as 50% on second frame, set to 25mA as 25% on third frame....etc.

    2. If yes for first question, Did it have dim(gradient smooth change) function internally during current change?

    3. Does LM3644 have two ways to lower the current? One is changing the voltage by I2C, the other is changing by PWM. Is the 7bit for PWM only? How about using I2C changing?

    Thank you!

    Regards,

    Patty

  • 0 in reply to Patty Chuang
    TI__Mastermind 22745 points

    Hi Patty,

        1. No, for torch mode, you can only change the current through the I2C interface;

        2. No.

        3. LM3644 can only change the current through I2C, 7bit is for I2Cnot for PWM. When you want to change the current, you need to change the reg 0x05/0x06(Torch current)

    Regards

    Sean

  • 0 in reply to Patty Chuang
    TI__Mastermind 22745 points

    Hi Patty,

        Is there any more question? I'd like to close this one first if you don;t have more question.

    Regards

    Sean