My boost driver not boosting?

[chefla]

I agree ^^. This IC does not have a true output disconnect, so if your control pin is low, your booster is switched off and your output voltage will be a little less than your battery voltage.

 

[benmwv]

I am not building this driver for red diode. Just because I saw the output voltage is 3.98v only so I try it with my red diode.

I still cannot draw more current from this driver. Is this IC supposed to provide 1.2A for a 445nm diode? Even if the efficiency is calculated I still should get around 800mA-900mA but not 300mA only. Any recommendation?



I only request one sample from TI. I cannot tell whether this is a defected unit but from what I see the IC should working maybe the value of some outside component is wrong.

Didn't you say you were using a red diode as a test load?

As said before, 1.2A was the switch current. Assuming your inductor can handle the max switch current and your design is good you should be able to get around half the switch current out to a 445 diode.

Sorry my DC is down for some reason and so I cannot upload the picture of the driver just the moment. I leave the CTRL pin empty and I am using a 18650 for the test.

I agree with the others, control pin needs to be high for it to work.

Once you fix the control pin you better test it on a real test load not a red diode or you might damage it! The output voltage has to be more than the input voltage for a boost only IC.

 

[AnthoT]

Here's a good test load that's not too expensive for you http://laserpointerforums.com/f39/fs-selectable-test-load-up-3a-assembled-diy-kit-stock-63450-4.html. It's selectable too so you'll never need to solder and desolder every time you want to change the setting :beer:

-Anthony