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Step-up converter without a transistor

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kender

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transistor step up

Colleagues,

I need to make a small unregulated step-up that would boost +2.7V from a depleted battery pack to approximately 7V to run an LCD, which consumes micro-amps. Is it possible to do this with a current that comes from the microcontroller pin (with PWM), some passives and a diode. I guess that could be possible, if the output of the microcontroller were open drain.

I’m not a power supply specialist; I’m just playing with this an idea. EDIT: this is more of an exploratory question rather then a search for a solution for a particular problem.

Please let me know if what I'm describing is unclear.

Cheers,
Nick
 

transistor step-up regulator

Make a doubler with diodes and capacitors and double-doubler....
 

single transistor step-up converter

Try LM2577 step up regulator.
It can accept a wide input voltage of 3.5Vdc to 40Vdc,
stepping up your voltage higher to output of 5V, 12V, adjustable.
The choice of output dpend on the IC model number.
The performance will drop if input voltage is lower, for example your case of 2.7V.

**broken link removed**

You can try other IC, using the keyword DC-DC step up regulator.

Best Regards,
Siong Boon
 

step up transistor

Hi,

You might want to consider a charge pump.

Something like Microchip TC7660

Just a thought. Good Luck

dfullmer

It is also possible to make a simple oscillator from an inverter then voltage double the output capacitively.
 

servicemann said:
Make a doubler with diodes and capacitors and double-doubler....
I thought about a charge pump double-doubler too. But the part count for it would be greater then for an inductive step up with MOSFET.

Added after 45 minutes:

dfullmer said:
You might want to consider a charge pump.
Something like Microchip TC7660
Just a thought.
This is a good thought in a wrong direction. I want to shake out as much hardware as I can. Adding an 8-pin IC is a diametric opposite.
 

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