# Voltage booster schmatic

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#### sfink06

##### New Member
Hi all,
I am having trouble getting this circuit to work correctly. The output of the voltage booster does not stay as high as it should be. Someone here told me that they think the voltage booster and pic power lines need to be separated, but I haven't tested this idea yet. Is there some problem with the way it is drawn?
Thanks.

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#### Electronworks

##### New Member
Ok, without the chip numbers, it is difficult to work out if your circuit is correct or not. I am assuming the component between P$1 and P$2 is an inductor.

Also if CO is your output capacitor, it looks a little small. I would make it 100uF and see what happens then.

Do you have a reference circuit to work from in the datasheet?

Also your feedback resistors are rather high. Unless you are running this circuit off a lemon, bring them down by a factor of 10 for better stability.

I also don't think you need RF3. This will only slow down your response time

Let me know

#### sfink06

##### New Member
The voltage booster is TPS61081 from TI.

#### blueroomelectronics

##### Well-Known Member
What's your voltage / current in and what do you want out?

#### sfink06

##### New Member
okay, the PWR signal here is a 3V battery, so I expect 20V out. The output is then fed into these transistors here. I actually need 120 mA (I think thats right...) out of the transistors. I have tested the voltage booster and it works fine by itself, but when I connect it in this circuit with the PIC running It doesn't put out 20V like it should. My friend suggests that the PIC clear pin may be falling low, but that doesn't sound right to me.

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#### blueroomelectronics

##### Well-Known Member
What sort of 3v battery? A coin cell?

#### sfink06

##### New Member
I think this is the model... its from Full River LP30 FR Bahoma 3.3V 30mAh

#### blueroomelectronics

##### Well-Known Member
Ok That battery puts out 600mA max, and you need more than 800mA and with the inefficiencies of the inverter closer to 1A or more. You need a bigger battery.
Are you running a motor or stepper? It'll probably need much more current to start than run.

#### blueroomelectronics

##### Well-Known Member
Just looked at your datasheet, that's a simple white LED driver is that what your driving?
It's probably a pulsed output.

#### sfink06

##### New Member
actually the transistors are running electro-thermal actuators.

#### sfink06

##### New Member
and yes it is a pulsed output

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