Low voltage LED driver circuit

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RQ1

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Hi all,

I am designing and building some led light models for testing prior to industrial design.

It is a simple, battery operated, low-voltage LED project. It will contain 5 white hi-brillance LED's and will have a 4.5v AAA battery source.

Goal is to have consistent current even as battery degrades. I suspect the goal would be 20ma until the battery can no longer provide enough power.

I am considering a boost convertor similar to this TI part. It seems to have several nice benefits:

https://www.electro-tech-online.com/custompdfs/2009/10/tps61062.pdf

In figure 20, on page 15, they show a 5-LED circuit, with the LED's in series.

It indicates a dimming feature in the opening description on pg. 1 via digital signal but I would like to add an analog brightness control to the circuit, something which will offer 0 to 100% and at 0, the LED's are disconnected from the circuit so there is no current drain.

It mentions using a PWM signal to achieve this. Any advice on how I would incorporate this?

Is the chip overkill for a simple LED device? I do need to regulate the current and boost when the batteries get lower. Any better solutions than this chip?

Thx D
 
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