# How to limit current going into DC/DC

In my project, I am using 12 solar cells in series as a power source. This is the link to the cell. Doing that will give me a power source of (3.6W * 12 = 43.2W) maximum and output voltage is (0.6 * 12 = 7.2V).

I want to use this source to power some sensors, such as this current sensor. I will power the sensors with 3.3V, therefore, I use this 3.3V DC/DC to get 3.3V. If I'm not wrong, the input current to the DC/DC should be milliamperes while my source can generate (43.2W / 7.2V = 6A) maximum.

I want to limit this current by using a resistor by connecting it to the input power pin of the DC/DC. Here are some questions I have at this point:

1. Does the solution of using a current-limiting resistor sound like a potential solution to my problem?
2. If so, how should I determine the value of the resistor? Should we look at the full load or no load current?
3. Is there any other solution besides using a current-limiting resistor?
• You don't have a problem. The 3.3V DC-DC converter will only draw as much current as it needs. Mar 18, 2023 at 20:53
• I agree with @Dave, the converter certainly should ok safe to supply from a low-impedance source and the solar panels won’t supply more current than they can generate. Unless there’s a reason that you haven’t disclosed there’s no need to limit current in any additional way.
– Frog
Mar 18, 2023 at 21:04
• A fuse might of course still be a good idea. Maybe a PTC polyfuse. Mar 18, 2023 at 21:26
• Thank you. I will look at the PTC polyfuse as well.
– Alex
Mar 18, 2023 at 21:40