Hi Stefan,

Thank you for your email. 

I have used the WEBENCH® POWER DESIGNER to run a simulation based on 

LM34936RHFR, similar to the LM34936EVM. I have attached the results. Is this efficient to design to 22-30V DC to 19.5V DC, 14A. or is the PMP21278 reference design a more better option? 

Kind regards,

Bright

3343.WBDesign20.pdf

Hi Bright,

both look OK for me - so using the Webench design might be easiest.

Best regards,

 Stefan

Hi Stefan, 

Thank you for the email. 

Considering the simulation form Webench that I sent regarding LM34936RHFR,  can use only one MOSFET per each 4 switch - part number CSD19502Q5B? The PMP21278 reference design  used 2 MOSFET each for the 4 switches. What are the pro and cons of using two MOSFETs in parallel for each of the 4 switches?

Kind regards,

Bright

HI Bright,

with 2 MOSFETs in parallel you will get:

- lower R_DS,on (as divided by 2) therefore lower on losses.

- have a better thermal spreading due to larger area

- will have higher switching losses as you have to switch 2 gate charges.

So it will end up in the defining the thermal performance of the circuit, heat dissipation, thermal spreading and cooling.

Best regards,

 Stefan