How to convert 24v to 12v?

[shai]

Hi, I have a schematic for a custom PCB that is already working. See attached image. It's converting 24v input to 5v and 3.3v output. I want to also add a 12v output. How can I go about modifying it to add 12v output as well? In case it matters, the 12v will power two vacuum pumps.

[DrDiettrich]

Duplicate the 5V converter and adjust the voltage divider for 12V output. Modifications may be required for driving inductive load - see application notes for the IC.

[Peter_Dodge]

Easy. Just get two of the same value resistors, twist two legs together, then connect one leg to ground, and the other to your 24v. The two legs you twisted together is your new 12v.

This is called a voltage divider

[bluejets]

In case it matters, the 12v will power two vacuum pumps.

What is the load current of these vacuum pumps..??
Are they to be driven directly from this new 12v source..?

[shai]

What is the load current of these vacuum pumps..??
Are they to be driven directly from this new 12v source..?

500 mA combined, they are hardwired to always on. Yes, directly from 12V. Currently I just copied the 5v output schematic and modified the resistors to output 12v. If someone has a better suggestion, please feel free to let me know.

[DrDiettrich]

Two 12V pumps in series can be powered by 24V. Remains the chance to power on and off both together.

[shai]

Two 12V pumps in series can be powered by 24V. Remains the chance to power on and off both together.

Can you please explain how come it can be powered in series from 24v? Any cons to doing this way?

[DrDiettrich]

Parallel: 2*250mA=0.5A
Series: 2*12V=24V