Achieving a larger voltage than the battery voltage

• tfoutz99
In summary, the conversation discussed the need for a way to output a larger voltage than 3.7 from a lithium battery and the possibility of using a charge pump setup or an opamp to achieve this. However, it was noted that these methods have limitations and may require swapping out capacitors or using a combination of methods. The suggestion of using DC to DC converters or designing one using ICs was also mentioned.

tfoutz99

Hi! I'm working on a circuit, and I'm trying to figure out a way to output a larger voltage than 3.7 from a lithium battery, and to be able to adjust that voltage when needed. e.g., output 10 V for 2 seconds, then 9 V for 2 seconds.

I looked into a charge pump setup (create a voltage across one capacitor, then another, then connect them in series). In my understanding, this permits setting the voltage to multiples of the source voltage, e.g.
3.7 V (source),
7.4 V (2 identical caps),
11.1 V (3 identical caps)...​

but this voltage cannot be adjusted to, say, 10 V without swapping out capacitors.

I know an opamp can adjust the output voltage, but again it can only bump up the output voltage up to the source voltage. Since it too is powered by the battery, this would be capped out at the source voltage.

Of course, a combination could be performed, where I triple the voltage (11.1 V), and then use an op-amp to adjust that down to 10 V. However, I would like to not have anything in the circuit be higher than what I need.

Is this possible?

(I'm really a novice at circuit design, so please let me know if there is anything I'm completely glossing over!)

Look into DC to DC converters or build your own little converter using ICs available from company like LTC etc. You should be able to find adjustable step up converters. Or design your own using those ICs and they have application circuits.

Thank you for your reply. That's exactly what I was looking for!

1. How is it possible to achieve a larger voltage than the battery voltage?

It is possible to achieve a larger voltage than the battery voltage by using a device called a boost converter. This device uses an inductor and a switching circuit to step up the voltage from the battery.

2. What is the principle behind achieving a larger voltage than the battery voltage?

The principle behind achieving a larger voltage than the battery voltage is based on the conservation of energy. The boost converter uses the stored energy in the inductor to increase the voltage beyond the battery's output.

3. Can any type of battery be used to achieve a larger voltage?

Yes, any type of battery can be used to achieve a larger voltage as long as it can provide enough current for the boost converter to operate. However, it is important to choose a battery with a suitable voltage and capacity for the desired output voltage.

4. Are there any limitations to achieving a larger voltage than the battery voltage?

Yes, there are limitations to achieving a larger voltage than the battery voltage. The boost converter can only step up the voltage to a certain extent, and the efficiency of the conversion process decreases as the output voltage increases. Additionally, the battery and the boost converter must be able to handle the increased voltage without damaging the components.

5. What are some potential applications of achieving a larger voltage than the battery voltage?

Achieving a larger voltage than the battery voltage can be useful in a variety of applications, such as powering high-voltage electronic devices, charging electric vehicles, and providing backup power in emergency situations. It can also be used in renewable energy systems, such as solar panels, to increase the voltage for efficient energy storage.

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