Hello
I want to convert 3.3V to 12V with MC34063AD. Has anyone designed the circuit or has the schematic?
You need a buck converter. Not easy to build yourself. But where comes the 3,3V from and how many mA will you use? 1mA @ 12V is 4mA @ 3,3V. The 3,3V from the on board converter isn't very strong. It is easier to go from 12V to 5V end 3,3V.
I want to convert at least 12V - 100mA from 3.3V - 500mA.
Is there a transistor that can allow 12 volts to pass through one of its bases by stimulating at least 3 volts?
didn't ask google yet?
Wouldn't that be a boost converter?
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You have absolutely no chance of making one yourself. It needs a PCB and the layout is ultra critical.
Even professional power supply engineers can't get it right in less that three PCB iterations, in my experience.
The cheap eBay buck converters are not much better.
A transistor only has one base not multiple bases, so I don't know what you mean by this. It sounds like a nonsense to me.
Back to the beginning.
12 Volts @ 100 mA is 12 * 0.1 = 1.2 Watts.
From
3.3 Volts @ 500 mA is 3.3 * 0.5 = 1.65 Watts
That's my read on what you want.
I would think you want a boost converter. You want to start with a Google of DC-DC Boost Converter. A Google of Boost Converter Circuits will give you an idea of how they work and easier bought than built. Take note of the minimum input needed for your desired output. Take note of efficiency.
Ron
Pololu has a well documented range.
This one could do, powered straight from your LiPo battery.
Leo..
The chip manufacturer has, and provides both the circuit diagram and a PCB layout in the MC34063AD data sheet.
Let me explain more.
I am making a device whose task is to read the values of a series of rs485 sensors and send it to the server via the Internet.
My sensors are powered by 12 volts. Therefore, 220 volts is converted to 12 volts dc.
Processing and sending data is done with an esp32. And an rs485 to ttl module is responsible for converting the values read from the sensor for esp. Both ESP and converter module work with 3.3V power supply.
What I want to do is to connect the esp and the rs485 converter to a battery charging module that has the ability to connect a solar panel that can maintain the connection with the server even during a power outage.
The power supply of the battery charging module is 5 V dc, which charges a 3.7 V lithium battery.
So, so far I'm feeding 220v ac to the device and converting 5-12v and 3.3v dc from it.
Now what I want is that the 12V sensors can also work with the battery, but because the output of the battery is 3.7V, a 3 to 12V converter is needed.
Difficulties:
- 12V solar panel charging module is rare, at least where I live.
- My sensors only work with 12V and they don't have 5V models.
The Pololu Wawa pointed to will work. It might get a little warm though.
12V @ 100mA will demand ~400mA from your 3.7V battery considering 80% efficiency. Note the below graph. This is max output current at free air. You are right on the border. The heat concern will increase as your battery depletes below 3.7V.
How long should this battery setup last.
As @2112 pointed out, the boost converter (400mA) and the ESP32 (100mA) will draw 500mA.
That's a big LiPo battery bank if it has to last a day.
It makes more sense to design a 12volt battery setup,
and power the ESP32 from that with a buck converter.
Leo..
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@2112 You are right. The amount of 100 amps at 12 volts that I needed was for several sensors, which I reduced to one to two sensors, which is reduced to 30 to 40 milliamps at 12 volts.
This is what I found. In no-load mode, it flows 10 mA. With the amount of current I need, a maximum of 50 milliamps flows from the battery.
I need to use the battery for about three to four hours. I hope to reduce the current consumption by using deep sleep and optimizing esp.
The test I did with a 500mah battery and without a sensor kept esp on for about 4.5 hours.
3W datasheet-final (1).pdf (524.1 KB)
This Apex is not very efficient in your input to output range. It's about 70% at best. The Pololu is a better design.
The Pololu stays above 80%
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