Step-up/Step-down regulator with higher max output current?


i’m new to the forum. I own a S18V20AHV variable output step-up/step down voltage regulator that is perfect for my LiFePO4 solar charging application with one major exception: its max output current of 2.0A is too low. My load is a ham radio transceiver that idles at about 150mA when receiving and draws around 2.5A when transmitting with no regulator in-line. With the S18V20AHV in-line, the transceiver can’t reach its maximum transmit power. So, I need a regulator with higher output power.

Huge pluses with the S18V20AHV are its high build quality, size, weight and low RF noise output–it generates no noticeable noise at the frequencies at which I’ve tested. These factors are critical to my application.

Does Pololu plan to manufacture higher-power regulators? If not, could someone either recommend a specific, higher power step-up/step-down regulator that’s comparable to the Pololu S18V20AHV, or recommend design factors that I should look for while shopping for a different regulator?


Hi, Dave.

We do not have any higher power step-up/step-down regulators on the immediate horizon, but we are always trying to expand our regulator selection. What input and output voltage range do you need?

I don’t have any particular recommendations on a higher power regulator or non-obvious design factors that would be easy to evaluate when selecting a new regulator.

If you really only need a few hundred mA more output current and you have some space, you might see if adding cooling to the S18V20AHV is enough. We have not tried that regulator with any external cooling, so I am not sure how much it would help, but it might be worth a try.


Hi Claire,

Thanks for your reply. When I transmit at full power, my radio draws less than 3A, I’ll try adding a heat sink, although I think I’ll be stretching the limits of the S18V20AHV. Where should I mount the heat sink? Directly on the inductor (which seems to be the component that gets hot), the underside of the board or somewhere else?


Yes, on top of the inductor is probably the best spot. I expect forced airflow would also help (and probably be more effective).


Thank you for that information. Unfortunately, after adding a Raspberry Pi to the circuit, when I transmit, the current draw immediately goes above what the regulator can put out when it’s cool. I tested a different regulator that put out the required current, but it was extremely noisy. I narrowed down other possibilities, inquired about one of them, and learned that it, too, is noisy. Finding a regulator that runs as clean as the S18V20AHV is proving difficult. A Pololu unit that puts out 13.5V at 5A would be a perfect fit for me. When can I order one? :wink: Could it be that your switching frequency is out of the range of frequencies that my transceiver receives?

Our S18V20AHV regulator switches at about 500kHz. What input voltage range do you need?

What are the other two regulators you tried? If you can’t find a high power unit with low enough noise, you might consider adding capacitance to the input and output of one of your other regulators to see if that improves them. You could also try searching for other noise reduction tips or filter circuits.