My boost driver not boosting?

[die4laser]

Hey guys so I finish my first 445nm driver base on tps611650
When I hook up the 445 diode to the driver nothing happen so I measure the Vout of the driver. I got the 3.9v reading while my battery is 4.0v (WTF? the driver is bucking?) So I hook the 650 diode to the driver instead and it seem to work fine. It output a stable 300mA and when I change the sense resistor the current change seem to match the calculation from the data sheet.

My set up is exactly the same as above except I change the input and output cap into 10uf. If anyone can tell me what I am doing wrong it will be greatly appreciated.:thanks:

 

[chefla]

At 350mA the 445s are taking around 4V iirc. Decrease yor battery voltage...
What is a 650 diode? The red LOC or LCC types need even less voltage (2.6/2.7V) at 350mA. So something is wrong here...

 

[AnthoT]

Yes at 300mA that is what it should be outputting so your driver worked fine if you turn it up past 600mA then you will see it start to boost I am pretty sure

-Anthony

 

[die4laser]

At 350mA the 445s are taking around 4V iirc. Decrease yor battery voltage...
What is a 650 diode? The red LOC or LCC types need even less voltage (2.6/2.7V) at 350mA. So something is wrong here...

I am using a dead ML101J26 from Mitsubishi as a test load. Just curious what do you mean by LOC / LCC? Isn't that only a infra red diode have a 2.6/2.7V voltage drop?

 

[die4laser]

Yes at 300mA that is what it should be outputting so your driver worked fine if you turn it up past 600mA then you will see it start to boost I am pretty sure

-Anthony

I really won't consider my boost driver is worked fine since I can never get a output voltage higher then the input voltage. I have even replaced the inductor value from 10uH to 100uH. I even remove the inductor and simply bridge the pad and the driver is still working with the same result.....

The one thing that I find very strange is the driver will give a >8v no load voltage at the moment I hook the battery but then drop and remina stable on 3.98v. Is there any kind of limit on the IC? What am I doing wrong?

 

[AnthoT]

Well it depends what the diode is pulling from the driver. With the info you've provided this is what I could help you with. If you can provide some pictures of your board then that may help me help you

-Anthony

 

[benmwv]

Why would it boost for a red diode?

The driver will make the output voltage whatever it needs to be for the diode to draw the set current. If you want it to boost use a proper load.

 

[AnthoT]

Why would it boost for a red diode?

The driver will make the output voltage whatever it needs to be for the diode to draw the set current. If you want it to boost use a proper load.

His ic is a buck-boost so it's running the red diode in buck mode


But also why would you need to boost for a red diode????

-Anthony

 

[benmwv]

His ic is a buck-boost so it's running the red diode in buck mode


But also why would you need to boost for a red diode????

-Anthony

The IC is boost only, not boost-buck.

Not sure what you are trying to say :thinking:
You attempted to answer my (rhetorical) question, then asked it again.

 

[AnthoT]

The IC is boost only, not boost-buck.

Not sure what you are trying to say :thinking:
You attempted to answer my (rhetorical) question, then asked it again.

Ok I apologize I thought he was using this ic TPS63020 not the TPS611650. This is a boost only ic but I got mixed up for a second there. But then it's up to him to answer the question why he is using this for a red :thinking:

-Anthony

 

[chefla]

Did you take ESD precautions? These ICs need to be handled carefully. You could have damaged it. I have been there before. Once the opamps or fets are blown, these devices start to behave funny...

 

[justinjja]

What do you have CTRL hooked up to?
You schematic shows 5v, But you mention a battery,
what battery are you using

Got a pic of your setup?

Also what are you using as D1?

 

[die4laser]

Why would it boost for a red diode?

The driver will make the output voltage whatever it needs to be for the diode to draw the set current. If you want it to boost use a proper load.

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?

Did you take ESD precautions? These ICs need to be handled carefully. You could have damaged it. I have been there before. Once the opamps or fets are blown, these devices start to behave funny...

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.

 

[die4laser]

What do you have CTRL hooked up to?
You schematic shows 5v, But you mention a battery,
what battery are you using

Got a pic of your setup?

Also what are you using as D1?

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.

 

[justinjja]

Is this IC supposed to provide 1.2A for a 445nm diode?

No, It has a 1.2A Switch
Roughly meaing:

you can take in 1.2A from your 4V battery
Giving 4.8W in
-efficency

So with a 445 .7A mabye

 

[justinjja]

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.

Check your datasheet,
but Im pretty sure you need to hook up CTRL to Vin