LM3644: Application with 2V VCSEL

Hi Ondrej,

Though I am not familiar with VCSEL, I think you need constant current driver to drive VCSEL like LED. Right?

If this is the case, then what is your input voltage range?

Best Regards,

Steven

Hi Steven,

thank you for your reply.

You are right, I need constant current driver. I would like to drive the VCSEL by 600mA then the Vf is in the range 1.8-2V (depends on the temperature of the VCSEL).

BR,
Ondra

Hi Ondrej,

Got it. Then what is your input voltage range?

Best Regards,

Steven

Hi Steven,

sorry I overlooked previosly.

Most probably we will use 3V or 3.3V as a power supply.

BR,
Ondra

Hi Ondrej,

Then a Buck LED driver may best fit your case. Currently we do not have such kind of Low-Vin Buck LED driver.

Besides, I will check if LM3644 could work in pass mode for this application.

Best Regards,

Steven

Hi Steven,

I like the LM3644 for the other features too. TX interrupt and NTC monitoring is useful in my project too. 

So I would love to use LM3644 if possible.

BR,
Ondra

Hi Ondrej,

Understood. I will have a check on LM3644.

BR,

Steven

Hi Steven, 

Do you have any update?

I have one point about my selection of Vin to 3-3.3V.

I choose it to minimize power losses because the in Pass Mode the difference between Vin and Vled will drops on the IC. So with higher Vin the power loses will be increased. If you have better solution how to minimize power loses (even different IC) I am open to it.

Thank you,
Ondra 

Hi Ondrej,

Not yet. I am out of office today. I will check it tomorrow.

BR, Steven

Hi Steven,

do you have any update? 

Thank you in advance,

Ondra

Hi Steven,

could higher Vin help with this issue (or at least lower the probability of switching into short circuit prevention)? To be specific we are considering 4.2V. 

BR,
Ondra