LM61495: LED power source (8V/10A)

Petr Zkrat

Part Number: LM61495

Hello,

I am looking for some LED driver capable of 8V / 10A output (constant current). Vin is 14-28 (24 nom). Current is set by PWM. Is there any reference design avalibale for this application?

My current idea is to use buck (f.ex. LM61495) with opamp in the feedback loop for setting the current based on voltage at current sense resistor (and also by Vref set by PWM). Current plan is to set the crossover frequency to about 10% of Fsw, alre there any other general recommendations, or some reference design for this application?

Application is pretty much space contrained, thats why DCDC with internal switch was chosen.

Thanks

Petr

over 1 year ago

0 Jimmy Hua over 1 year ago

TI__Mastermind 47060 points

Hi Petr,

It sounds like you want to do a constant current/ constant voltage application to drive LED or charge batteries.

In this case, perhaps you light want to take a look at this blog to address this design (https://e2e.ti.com/blogs_/b/powerhouse/posts/how-to-design-a-simple-constant-current-constant-voltage-buck-converter).

I have not personally tested this but the methodology discussed in this blog should help provide guidance for your design and validation of the system.

Regards,

Jimmy

0 Petr Zkrat over 1 year ago in reply to Jimmy Hua

Intellectual 410 points

Hi Jimmy,

thanks for the link. That method is indeed intersting,however I need to use highly intergared IC that does not have the CM ouput I think the "traditional" method might be a go to. However, where should be the PWM voltage put in there?

Thanks

Petr

0 Jimmy Hua over 1 year ago in reply to Petr Zkrat

TI__Mastermind 47060 points

Hi Petr,

I was able to dig up an application note and found the "traditional method" circuit for CC/CV which can be seen in Figure 1. Perhaps this might be the more appropriate approach for your application.

Regards,

Jimmy

0 Petr Zkrat over 1 year ago in reply to Jimmy Hua

Intellectual 410 points

Hi Jimmy,

thanks for suggesting an alternative approach. However how would you incorporate PWM into that?

0 Jimmy Hua over 1 year ago in reply to Petr Zkrat

TI__Mastermind 47060 points

Hi,

The app note details that the constant current (IOUT) is set by equation 1, and is a result of Rin, Vfb, Rfb, and Rsense.

This topology may not be appropriate if you need to control the current with PWM.

Unfortunately there isn't a reference design that I can point to for constant current controllable through PWM.

Regards,
Jimmy

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LM61495: LED power source (8V/10A)