MOSFET for 10W boost converter

[eem2am]

10w boost converter

hello

i am doing continuous mode boost converter for LED driver:-

Vin = 8 to 17V
Vout = ~28V max
I out = 350mA
Power out = 10W.

Maximum FET Drain current is 2A.
Switching frequency = 510KHz.

PWM controller IC = LTC1871.

....Due to the potentially low input voltage , the switching mosfet will have to be a logic level FET.

The PCB that it must be built on is just 6.5cm by 1.5cm and double sided.

As you can imagine, it is crammed and there is no room for any appreciable heatsink.
-There isn't even that much copper PCB area to spare for the drain node of the FET to aid cooling.

There is no fan to cool it.

The LED board is however, MCPCB , and its screwed to a heatsink.

Considering my inability to use much of (or any of) a heatsink for the FET , what are your thoughts on using this SOT223 FET (BSP318S):-

**broken link removed**

-Or do you think the following IRLR120 D-PAK (chunkier looking) MOSFET would be better?

http://www.datasheetcatalog.org/datasheet/irf/irlr120.pdf

At this high frequency , i reckon the switching losses are going to be the decider.

So i am thinking of going for the smaller SOT223 and snubbering it to shift out some of that current and reduce the switching losses a bit.

Have readers any thoughts on a great MOSFET for this application?

 

[sdmieu]

Re: 10w boost converter

hello

i am doing continuous mode boost converter for LED driver:-

Vin = 8 to 17V
Vout = ~28V max
I out = 350mA
Power out = 10W.

Maximum FET Drain current is 2A.
Switching frequency = 510KHz.

PWM controller IC = LTC1871.

....Due to the potentially low input voltage , the switching mosfet will have to be a logic level FET.

The PCB that it must be built on is just 6.5cm by 1.5cm and double sided.

As you can imagine, it is crammed and there is no room for any appreciable heatsink.
-There isn't even that much copper PCB area to spare for the drain node of the FET to aid cooling.

There is no fan to cool it.

The LED board is however, MCPCB , and its screwed to a heatsink.

Considering my inability to use much of (or any of) a heatsink for the FET , what are your thoughts on using this SOT223 FET (BSP318S):-

**broken link removed**

-Or do you think the following IRLR120 D-PAK (chunkier looking) MOSFET would be better?

http://www.datasheetcatalog.org/datasheet/irf/irlr120.pdf

At this high frequency , i reckon the switching losses are going to be the decider.

So i am thinking of going for the smaller SOT223 and snubbering it to shift out some of that current and reduce the switching losses a bit.

Have readers any thoughts on a great MOSFET for this application?

Hi, I want to know that u find what u want?
Because I need to discuss u about some of your experiences about this boost converter

 

[goldsmith]

Have readers any thoughts on a great MOSFET for this application?

Hi eem2am
Such a long thread just for asking what kind of mosfet for a boost converter ? for a boost converter , all of the things that we need are i/o voltage rating and maximum out put current and frequency of operation . that's all !
For your purpose :

Vin = 8 to 17V
Vout = ~28V max
I out = 350mA
Power out = 10W.

Maximum FET Drain current is 2A.
Switching frequency = 510KHz.

There are many many choices . like : IRFZ44 / IRF740 .... etc
Best Wishes
Goldsmith

 

[Eshal]

@sdmieu
Hi! I also want to help you because I am working on boost converter. By the way, goldsmith can help you a lot. He is very good in power electronics and analog electronics. If you have issue then please post a thread and I will contribute with you.
See ya.