[Pervil]

Hello, I am looking for a miniature step-down (buck) converter with maximum dimensions of 5mm (height) x 15mm (width) x 30mm (depth). The board needs to step down the voltage from a 3.7V 400mAh lithium battery to 2V 400mAh, with as little power loss as possible. I have searched online, but the options I found (listed below) do not meet my requirements—either the input voltage range is wrong, or the output voltage range is, or both. Could someone please help me find a board that would allow me to achieve this goal with little to no soldering required?

I would appreciate relevant and helpful responses.


UNSUITABLE options:

MP1584EN Buck Module:

Input: 4.5V–28V
Output: 0.8V–20V (adjustable)


LM2596 DC-DC Buck Module:

Input voltage: 4V–35V
Output voltage: 1.23V–30V


Mini360:

Input voltage: DC 4.75V–23V
Output voltage: DC 1.0V–17V


MT3608:

Input voltage (IN): 2V to 24V DC
Output voltage (OUT): 5V to 28V DC

 

[rainyliveshere]

One thing to consider is the TPS62740 from Texas Instruments. It supports a 2.2–5.5 V input and an adjustable output from 1.8 to 3.3 V, making it suitable for a single Li-ion cell and a 2 V output. Its low quiescent current is also useful for battery-powered applications.

The main catch is that the TPS62740 is an IC, not a ready-made miniature module, and its evaluation board may not meet your size requirements. If you need a solution with minimal soldering, make sure to verify the dimensions and output-voltage configuration of any prebuilt board before buying.

For some background on buck-converter operation and efficiency, this guide to AC-to-DC converter circuits may also be helpful.

One important detail: what is the maximum current your load needs at 2 V? The battery's 400 mAh rating indicates its capacity, not the required output current. That information will help narrow down a suitable converter.

 

[Harald Kapp]

What is your current requirement? I suppose with a 400 mAh battery you will need only a few mA, right? In that case you may want to consider a low drop linear regulator (LDO). For a selection of these see e.g. here. The TLV0220 for example is very small and requires only two external capacitors: