TPS922052: CV mode led driver

Hi Bekir,

May I understand why cv mode is more efficient for your parallel LED connection? What's your input voltage, LED string voltage and LED current?

Best Regards,

Steven

Hi Steven,

Let's say we have 8 series 7 parallel led connection and total led current 700mA. In theory, each string will get 100mA. And if we cut off one rope, there will be six strips left in the circuit, and the current flow in each strip will rise to 116mA. This high amount of current will cause damage to the LED lights, so it is better to use a constant voltage LED driver in LED strips/strings.

Input voltage 48V

LED string voltage 24V

Hi Bekir,

I understand your concern.

However, if you are going to drive an LED string with a CV regulator, you cannot guarantee that the output current will be 100mA * 7 (Let's continue on the example you used above) and each string will get an equal 100mA due to LED manufacture variation. 

If you want to maintain equal current and open protection to each string, I recommend you try this method: first step-down your 48V input voltage to a middle level, for example 27V, then use a multi-channel LED driver like LM3464 / LM3463 to drive each string with separate channel.

Best Regards,

Steven

Hi Steven,

Thanks for the suggestion. My system needs very high pwm dimming ratio and accuracy. I think LM3464 / LM3463 doesn't provide that features. But ı will use these multi-channel driver someday.

Best Regards.

Hi Bekir,

May I understand what are your PWM dimming ratio and accuracy requirements?

Best Regards,

Steven

Hi Steven,

Requirements are unclear yet. But it's better have minimum 2,000:1 dimming. Going back to your first answer. Yes, each strip cannot guarantee that the output current will be get equal 100mA * 7. But if cut off one rope, other strip will not affect that. That is why ı think cv mode is more suit than cc mode. So if I want to start the TPS92205x driver in cv mode, how do I do this?

Thanks for the answers :)

Best regards.