Hello,
For a project I have to use an lt1618.
My Vin = 4V with 1.1A and I want to convert that to Vout = 5V in 0.6A.
I first used this design and with the right R1 and R2 i'm able to get Vout =5V but the issue is i can't regulate my current at all, i'm getting Iout=Iin.
I'm guessing i'm using the wrong design.
Can anyone help me and tell which application is the i need?
Here a link to the datasheet.
--- Updated ---
I can't think of a scenario where you'd want that. Can you tell us what you're trying to accomplish?Oh so i'm using the wrong regulator, i can only fix my Vout. My Iout is based on the load.
Is there another convertor that could do that? Regulate Vout and Iout at the same time?
It's a school project.I can't think of a scenario where you'd want that. Can you tell us what you're trying to accomplish?
No, you don´t design a LED supply by it´s input current.It's a school project.
I wanted to use the lt1618 as a led driver powered by a battery of 4V at 1.1A.
To increase the autonomy of my system i was thinking of limiting my Iled.
No, you don´t design a LED supply by it´s input current.
You design it to match the LED = output current.
Klaus
I don't get the choose what i can use, i have to use what i was assigned.Then what you want is a voltage regulator (as you have) with a current limiter. You might be able to find one with built-in current limiting, or add it as an external circuit.
Also, there are dedicated LED drivers...
As I understand the challange is to use LT1618.ou can use the LT7805
Ty for LTspice, i didn't know it and it's really useful!You can use the LT7805 which will regulate vout, and then clamp iout to a set maximum if you want.
Download the free LTspice simulator and put your cct in there.
If you need help i will do it for you.
What is your LED load?.......Is it a 5V LED string?.....you know you cant drive a led voltage less then vin from a boost converter.
this is what a typical boost converter does.But here I have a new issue, when I use my LT1618 the whole system is working great i have Vled at 5V and my Iled at 0.25 but when i shutdown my LT i get for some reason Vled=Vin, as if shuting down the LT turned it into a simple wire.
That is what I thought.Hi,
this is what a typical boost converter does.
See the path:
Vin --> R4 --> L1 --> D1 --> L+
there is no switch to shut down the output.
/SHDN just shuts down the BOOST part, indeed most parts of the IC to reduce IC current consumption.
.. but there is not "switch output off"
A simple P-Ch MOSFET will do.
Or an N-Ch Mosfet in GND path of the LED.
Yes but my input voltage variation isn't that big I don't think it will cause an issue.BTW: R4 just limits the switch current. Thus the output current will vary with input voltage.
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