LM3630A: LM3630A / VREG_CS and VHR

Hi Team,

My name is Kanemaru, FAE at Macnica (Distributor in Japan).

I'm Satoshi’s colleague.

I have the three questions.

[Q1]

I understand that “VHR” is the spec of VHR Min block.

Is my understanding correct?

[Q2]

I understand that “VREG_CS” is the voltage applied to ILEDx pin.

Is my understanding correct?

[Q3]

I would like to know the maximum voltage applied to ILEDx pin at ILED=20mA (Brightness is 100%).

Could you please let us know if you have any information?

I’d greatly appreciate your verification.

Regards,

Kanemaru

Hi Caryss-san,

Thank you for your response.

I understand that “the currents sinks require less headroom at lower ILED currents than at higher ILED currents”.

However, “VHR at ILED = 95% of nominal, ILED = 20 mA” is smaller than “VREG_CS at ILED=5mA”.

Is this correct?

And, I would like an answer to "Q3".

*This value does not need to be a guarantee.

Regards,

Kanemaru

Hi Caryss-san,

I found LM3697 (Similar device of LM3630A).

According to LM3697 Data sheet;

-VREG_CS at Auto headroom off

-VHR_MIN at no comment (so I guess that Auto headroom on)

And, LM3630A has “Adaptive Headroom” function.

Therefore, I guess that;

-VREG_CS at Adaptive headroom off

-VHR_MIN at Adaptive headroom on

Is my understanding correct?

If yes, I have one more question.

Does this device control “Adaptive headroom ON/OFF” by "FB_EN_x” resisters?

If you could reply by today, it would be very helpful.

I’d greatly appreciate your verification.

Regards,

Kanemaru

Hi Caryss-san,

Thank you for your response.

I understand that we can’t turn off the adaptive headroom function. 

And, I understand that these two parameters (VREG_CS and VHR_MIN) are defined under different LED condition (it is your comment).

So, is a symbol of "VREG_CS" an error in writing?

Regards,

Kanemaru

Hi Caryss-san,

Thank you very much for your help.

I understand. Thank you very much.

Regards,

Kanemaru