i want to power 6 LEDs from a 12v to 24v automotive(alternator/starter) battery power source.
would like to run LEDs at 350mA each. LED Vf can be up to 3.7v.
heatsink capacity is 10 watts.
i want pwm driver with load dump, reverse polarity, and transient voltage protection.
could anyone recommend a driver chip and circuit design?
thanks

 

I don't have circuit/chip for you but a suggestion. There are literally hundreds, maybe thousands, of chips to choose from. Go to the major manufacturer's web sites - TI, AD, .... Each of them has design pages to help you make a selection. There are data sheets and application notes with actual circuits to look at.I would winnow it down to just a few possibilities and then maybe come back here to ask any unanswered questions.

 

yes i've looked at 100s of chips.
i prefer the simplest possible like a PAM2861.
i thought there might be something better.
i have trouble selecting inductor and capacitor values to set frequency.
thanks

 

I like the PAM series. Very simple to use. I wouldn't sweat the inductor too much - the larger it is, the lower the switching frequency. With 6 LEDs, I'd probably go for a 100 uH, 1A. The only issue is if it makes audible noise but kind of unlikely (then cut the inductor size). Their advice on the cap is pretty simple. I'd probably just use a 10uF low ESR. However, you should look at the charts on 5 and 6 of the DS to help understand the relationship between inductor size, input voltage and efficiency.

I presume you are aware that you need to feed that chip with a Vin of at least 6*Vf max (that is your LEDs Vf max). It's not stated in the DS anywhere.

Other manufacturers have more design help than Diodes Inc. Their DS is pretty minimal.

 

i'm running 2 strings of 3. only concern is enough overhead voltage for 3 from a 12v supply.
thanks for explanation of inductor and capacitor values.
what's another similar chip with better design help?
thanks again.

 

can't give you a chip but take a look at TI.

 

i looked at ti chips but their stuff is too complicated for me.
i have another circuit that drives just a single 1watt led(350ma) with a 12 or 24volt automotive type battery system.
i'm using same pam2861. what value inductor and cap would it need?
thanks

 

Hello,

Have a look at the LM3407 from National.

Bertus