SMPS component values

[itsfebin]

smps design values inductor and capacitor

Hi,
I would like to design an SMPS boost ckt with 3.3V i/p and 3.3 -12V output voltage range at a power of 5W. How do I find suitable values for the inductor and capacitor? can someone help? It'll be great if you can give me some references as well...

thanks and regards,
Febin

 

[LordAli]

smps component

Look there

**broken link removed**
https://www.smps.us/Unitrode.html
https://www.smps.us/Unitrode2.html

 

[itsfebin]

smps output voltage management

thank you

Also, I need to bring up a voltage from 1.2V (single battery cell) to 3.3V to drive a PLD. Can you guide me on this as well?

warm regards,
Febin

 

[LordAli]

tsp smps

You can use something like TPS61097-33 or TPS61221 for your PLD powered from 1,2V battery. Depends upon the PLD consumption. Equations are in the datasheet.

If you look at power management on TI at this path

TI Home > Semiconductors > Power Management > Non-Isolated Switching DC/DC Regulators > DC/DC Converters (Integrated Switch) > Step-Up Regulators
you can choose whatever you need.

If TI don't satisfy you, you can look at Fairchild, ON semiconductor, STMicroelectronics for other ICs. :wink:

 

[itsfebin]

s m p s componant

Hi,
Thank you.
I took a look at the data sheet of UCC29412 which is suits my need. I was trying to understand the design and it is mentioned that "An inductor value of 22 μH works well in most applications, but values between 10 μH to 100 μH are also acceptable." If the value of L is fixed as 22uH, a required output voltage can be achieved by varying the duty cycle of the input pulse to the power transistor. I have decided to use a multivibrator to drive the gate of the power transistor. Is there any formula to estimate the duty cycle of input pulse or do I have to find it by trial and error method?

best regards,
Febin

 

[LordAli]

component of a smps

UCC29412 have integrated switch. Schematic included in datasheet.