2
\$\begingroup\$

While browsing for a switching voltage regulator, I noticed that Semtech TS30011 and TS30012 have the exact same characteristics and price, only that the former has a max output current of 1A, and the latter of 2A.

(Direct link to combined datasheet for both devices is currently here.)

I mean it seems a no-brainer, why would I get the 1A version when the 2A costs the same and has the same package? Maybe I don't need 1A on my current project, but who knows in future.

What changes inside to allow for more/less output current without changing the package and price?

\$\endgroup\$
1
  • \$\begingroup\$ You will have different inductor saturation currents. \$\endgroup\$
    – Jens
    Commented Nov 12, 2022 at 15:44

1 Answer 1

3
\$\begingroup\$

The output current of these devices is set by their own switch current limiting. So it's not so much that the device can withstand a certain amount of current, as it's that the device will allow a certain amount of current (download the datasheet and look at the "Over Current Protect" ratings of the devices listed).

Changing the over current protection setting is a matter of changing the values of an internal voltage divider; probably the entire chip design except for that is the same, across the line.

The inductor that you choose for your regulator circuit needs to be matched to the device's over current protection specification. If you allow too much current through the inductor, then either the inductor will overheat, or it will saturate and the regulator may be damaged.

Even if the circuit as a whole is guaranteed to draw no more than a certain amount in normal operation, during startup, when the output capacitor is charging, the regulator may well be driven into current protection mode.

Inductor volume and price are roughly proportional to their maximum and average current, so even where all else is equal, choosing a regulator to match your circuit's needs means you may be able to choose less expensive passives to put around it, and reduce your board space to boot.

\$\endgroup\$

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.