RGB Strip driving using LM3414 - help needed

Thread Starter

mishra87

Joined Jan 17, 2016
851

Thread Starter

mishra87

Joined Jan 17, 2016
851
Since the RGB strip is another board so does Short Circuit protection needed apart from from current limiting resistor in LM3414 ?
 

pmd34

Joined Feb 22, 2014
518
Hi Mishra,
Patience patience!
The LM3414 is effectively providing a step down voltage conversion the voltage it will actually end up outputting is determined by how much current your LED will take.. (and the resistors used to program the IC).

So in your case, if you set up the circuit shown in the application schematic, with the correct values for your 20mA current, you do not need a limiting resistor.. it will supply the LED with what ever voltage is needed to get 20mA flowing through it.

However as you are only using 20mA in the first place (which is quite small), you could simply use the circuit diagram you have pasted in. Use a resistor to drop the unwanted voltage (18-5)V @ 20mA...

This is of course a bit wasteful as you are just dissipating I^2 R of heat and only delivering 5Vx20mA of useful power to the LED. Hence when you want to be more efficient you use something like the LM3414. Which uses a switching buck regulator configuration to only provide as much voltage as needed to power the LED.
 

Thread Starter

mishra87

Joined Jan 17, 2016
851
Hi pmd34,

Thank for your reply and time.
In my application i have to drive 28 RGB led using LM3414.

So for 28Red Led i will use one LM3414 driver and one for Green and one for Blue.
So i will use 3 LM3414 to drive total 84 leds

So iwill drive 28 parallel Leds using one lm3414 with if=10mA

1576348239953.png
 
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