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LM3410: LM3410: for one LED Vf=2.95 and I= 1A

koho
Prodigy 220 points
Part Number: LM3410

Hi,

I am trying to use a constant current LED driver.

My input is Vin = 3.3V and PWM = 1khz (duty cycle is 0 to 50%). I would like to control one LED (Vf= 2.95) with 1A.

So I set up based on the datasheet, which I follow the typical circuit (R1=200m ohm).

1. First, I wonder LM3410 is a good option for me. I need a constant-current circuit (which can be 0.5A-1A) and PWM controls (1K and duty 0-30%).

2. I quickly tested it, but the output is not the same pulse as PWM. My duty cycle keeps changes, but the output is a constant value (approx 3V).

    My test condition is similar to Figure 27 (8.2.8 on page 27 datasheet). I also used the same value for C, L and R1.

    Can I have any simulation for this circuit (e..g, Tina)?

3. If this is not relevant, would you recommend any circuit that fits my requirement?

Thanks

  • 0
    TI__Mastermind 18890 points

    Hi Koho,

    The LM3410 is a boost converter.  It cannot support your you 3.3V to 2.95V application.

    Thanks Tuan

  • 0 in reply to Tuan Tran74
    Prodigy 220 points

    I know, but my max Vf is 3.3V then fine? Okay, let's say I use two LEDs 2*2.95, then is it working? If I really want to use one LED, then I can add more resistor in the load? Is it a bad choice?

    I want to confirm that the input PWM goes to output PWM with constant current.

    Thank you!

  • 0 in reply to koho
    TI__Mastermind 18890 points

    Hi Koho,

    As long as you do not violate the boost topology criteria then what you are doing is fine. 

    To answer your original question 2 above...We do not have TINA simulation for this part.  Please have a current probe on the LED current to verify that it follows the PWM input.  It's the current that will follow the PWM input not the output voltage because it's a current controller.

    Thanks Tuan