DC-DC Boost converter 2-24V to 2-28V 2A MT3908

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Official specifications:
I got this from Aliexpress store: FSXSEMI FengShengXIn Store

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Each module in a small plastic bag.

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The chip is supposed to have overload and temperature protection, but it is not reliable, I trashed two modules during the test.



Measurements

This chapter only contains a few of the measurement, click here to see all
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The module can work down to 2V, here I am generating 5V from a 2V input, current can be up to 300mA

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Increasing input voltage to 3V means 0.7A output current. The output voltage do not look completely stable, this is due to noise in the output.

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Boosting 3V to 15V reduces the output current to about 0.2A

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With 2V input the module can deliver 20V output, but not much current, here it is about 60mA.

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Looking at it another way: With 5V 0.2A output the module works below 2V input.

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It is also possible to get 12V 100mA down to 2V

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The chip needs some current to run, how much depends on input and output voltage. With 5V output and 3V input the chip uses about 6mA.

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Here is a one hour test with about 1.5W in the circuit, the power will be distributed between the chip, the diode and the inductor.

Temp7044

M1: 87.3C, M2: 87.1C, M3: 72.1C, HS1: 94.3C
The diode and the inductor is fairly warm, but the chip is rather hot at this load

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There is no obvious voltage jumps when turning loads on and off, but the output noise is rather high when the load is on. Maybe the problem is the capacitors, datasheet says to use ceramic capacitors.

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A look at the output noise.



A closer look

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The circuit is simple with input and output capacitor (C1+C2), inductor (L1), diode (D1) and a voltage divider (R2+W1) and the chip (U1) to do the switching.

TypicalSchematic

This is a typical schematic for the chip.

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Conclusion

The module works from 2V input and can in ideal conditions deliver up to 1A, but in most caSes the current will be considerable lower. The output noise is rather high and will usually require some filtering.



Notes

I got a 5 pack of this module from a reader