I am making a robot with multiple devices mounted on top. I am planning to buy either a 14.8v or 11.1v Li-ion battery which has internal BMS limiting maximum discharge current to 4A. Now I need 9v for my motors which will consume 1A each. Additionally I need a 12v and a 5v output to power Jetson Nano and another device. Ideally I would like all 3 outputs to support current up to 5A and minimum 3A so that if in future I buy a better battery and use Jetson Orin, the same power management circuit works for it. The best option I have found is using 3 step down buck converter modules. But is there a way to combine 3 separate buck converters to reduce the size of the PCB to as small as possible so that it can fit in my robot. A circuit/schematic will be really helpful. Additionally I also want to be able to charge the battery and power the robot with charging adapter when I want. So how do I isolate these two operations?

  • 1
    \$\begingroup\$ 'V' for volt. 'A' for ampere. Capitals matter! Paragraph breaks help separate writing into blocks of related sentences.. (Use 2 x Enter for paragraph breaks in markdown syntax.) \$\endgroup\$
    – Transistor
    Nov 19, 2023 at 19:23

1 Answer 1


To reduce unwanted interactions (e.g., motor noise vs. control circuits), it's an advantage to have three separate power supplies.

One might derive a 5 V supply from the 12 V rail with resistors and Zener diode if the 5 V requirement were for quite low current, but more likely, the 12 V needs will be low current and 5 V high current, instead.

There are some fairly small commercial converters, e.g. this at ~US$1.50 each, which handles only 3 A. The motors would likely need far more current when stalled than the fixed draw from other devices, so consider adding a supercapacitor to the existing battery and using a higher-current device for the 9 V motor line, e.g. this 5 A buck converter. [One cannot directly parallel voltage regulators for higher current.]

The devices above were just as examples. Also note that some may have high noise and ripple, requiring additional filtering.

  • \$\begingroup\$ I have found good small buck converters with 15A and even 30A rating. So if I have to do 3 seperate conversion, I can do that. I was just wondering if there was a way to combile all three in singal circuit which would have a smaller PCB size than 3 buck converters. But Thank you for youe help. \$\endgroup\$
    – devansh
    Nov 21, 2023 at 20:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.