Author Topic: PMIC question  (Read 916 times)

0 Members and 1 Guest are viewing this topic.

Offline roogadgetTopic starter

  • Contributor
  • Posts: 27
  • Country: au
PMIC question
« on: September 28, 2018, 12:25:46 pm »
I am designing the power management section for my project and I'd like some feedback on my design choices.

I am wondering about a PMIC chip (Boost/Buck Converter) that I've picked.

http://www.ti.com/product/TPS55165-Q1

There is a pin that requires an external 5V input when a 12V output in desired. (Power Good Pin - PG)


My input varies between 9V and 18V. So I would need to step it down to achieve the 5V required.

I also need a 5V output because my STM32 requires 3.6V (Which I'll likely use a linear voltage regulator to achieve).

I would like to know if this is the appropriate method to handle various inputs and stepping down voltages.  :-//


 

Offline stmdude

  • Frequent Contributor
  • **
  • Posts: 479
  • Country: se
Re: PMIC question
« Reply #1 on: September 28, 2018, 01:01:53 pm »
From the datasheet:
The power-good (PG) pin is a low-side FET open-drain output which is released as soon as the output voltage is
greater than the PG undervoltage threshold ....

It's an output, but you can't really put any load on it.

Which means, you'll need to convert your 12V output into 3.3V for the STM32.  Plenty of DC/DC bucks does this for very little money.

 
The following users thanked this post: roogadget

Offline roogadgetTopic starter

  • Contributor
  • Posts: 27
  • Country: au
Re: PMIC question
« Reply #2 on: September 28, 2018, 01:34:10 pm »
Wow! Thanks! I just avoided a big problem.   :-+
 

Offline T3sl4co1l

  • Super Contributor
  • ***
  • Posts: 22436
  • Country: us
  • Expert, Analog Electronics, PCB Layout, EMC
    • Seven Transistor Labs
Re: PMIC question
« Reply #3 on: September 28, 2018, 08:58:26 pm »
So you need what voltages?  Just 5V, with an LDO to make 3.6V?  (3.3V is more traditional, do you have a reason for going on the high side of that?)

That reg has a 5V output option, but it looks like a much cheaper buck regulator will meet your requirements in that case.

Tim
Seven Transistor Labs, LLC
Electronic design, from concept to prototype.
Bringing a project to life?  Send me a message!
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf