Multiple Buck Converters

Question

I have multiple buck converters, model XL4005 (datasheet ), fed from a 12V battery source to several devices i.e. My motors (require 12V), Arduino (requires 5V) and Transmitter module (require 3.3V).

Do I connect the buck converters in parallel and distribute the voltages to respective devices? Is it safe to do so? I saw some uses diode to even out the supply current but I'm not quite sure how, link: Is it ok to connect the output of buck regulator in parallel?

My specs:

Battery 3S LiPo datasheet = https://www.robotedu.my/index.php?route=product/product&product_id=448&search=battery+5200
motor BMA2826-4 1100 175g Ф35mm*54mm Ф5.0mm 3-5LiPo 25-37Apk 2.9A max
- datasheet = qty = 2pc
- max load = 25-37 Amp-seconds surge , 2.9 peak amp
  - means 25A *2 for my 3S pack with 2 motors
transmitter: 15mA @ 3.3V, 3.8V max.

You can't have different voltages connected together in parallel, but they can share common ground. — user103776, Jan 11 '19 at 15:42
Multiple Buck regulators in parallel can interact to cause low frequency noise depending on loads and battery ESR but if adequate low ESR on 12V, it is OK — Tony Stewart EE75, Jan 11 '19 at 15:43
What happens when all the buck converters draw current in the same phase? Can your power supply provide it? — Indraneel, Jan 11 '19 at 15:47
Buck converter no problem and LDO for Tx. But 2 motors on full surge is a problem. Can you limit acceleration? Is it a prop or wheel drive? — Tony Stewart EE75, Jan 11 '19 at 16:00

Rudy · Answer 1 · 2019-01-11T15:58:00.907

All the inputs of your converters can be connected to the 12V power source. There is no need for diodes.

If you want some clarity about additional diodes that others have used then please provide links to that information. They may be doing it with multiple power sources feeding different converters to prevent power going back into a turned off supply. (which is not what you are doing)

Edit- The link you provided was someone who wants to use multiple power supplies to obtain higher capacity for the same load. That is not what you asked for and it doesn't apply in your case.

Tony Stewart EE75 · Answer 2 · 2019-01-11T16:41:55.447

Suggested Incomplete Block Diagram

schematic

^{simulate this circuit – Schematic created using CircuitLab}

4A 5V DCDC looks good,
any 3.3 to 3.5V LDO is ok.
Sensor V TBD

20C 5.2Ah Battery means can handle 104A surges. Each motor surge is 25A for 3S.

ESC and motor wires must be twisted pairs and low R reduce stray current noise coupling to sensors that may need twisted pairs at right angles and/or separation.

Battery Notes also indicate... do not exceed 50% DoD on 1st 5 uses and do not exceed 80% DoD after.

Suggestion

Alternative is use 3.3V Arduino with mods and 3.3V DC-DC converter with RC - low pass filter to Tx to reduce ripple.

score 1 · Answer 3 · answered Jan 11 '19 at 16:43

How will you control Arduino?
How is Arduino connected to ESC?

schematic

^{simulate this circuit – Schematic created using CircuitLab}

20C 5.2A Battery means can handle 104A surges. Notes indicate do not exceed 50% DoD on 1st 5 uses and do not exceed 80% DoD after.

score 0 · Answer 4 · answered Jan 11 '19 at 15:49

Most electronic systems need to communicate and control, back and forth between the various modules of the system. This means charges flow back and forth.

These charges need a return path, and by convention the GROUND wires provide that shared path.

Some systems use Fiber Optic communications to avoid this "sharing".

Multiple Buck Converters

4 Answers4

Suggestion