24 to 12v SMPS heat issues

Hi,

I have a device that draws ~1A average but peaks at upwards of 10A for a few ms a couple of times a second, over a 1 second sample the average is 1A. It switches 24V down to 12V through a FDD4243 P-Fet and a 22uH 11A Inductor. The controller of choice here is a **broken link removed** Hysteretic Buck Controller.
Schematic is attached.

My issue is the temperature of the SMPS while opperating at load with 26V input. I meassured the PFET at 95°C and the Inductor at 85°C, they are both pretty close together and the inductors drain pad probably isn't as big as I should have made it, but it shouldn't really be running that hot? Or have I missed something? Should I perhaps have a different inductor or PFET ?

Any help is greatly appreciated!

I should mention the input is variable either 12V or 24V batteries. The system obviously runs pretty cool with 12V input.

you can not parallel diodes like that... you probably need a better fet and inductor, you definately need proper caps on the input and output, and you might considder the LM3489 that national has the designer software online for

Thanks Ubergeek63 Would a single 3A Schottky do there instead of the two?
The output side has 3 x 2200uF L/ESR caps on it and the input is just the 220uF but is only ever powered from large battery banks, is this an issue ?

Would the following P-FET be an better option?
FDD4685

Its hard to say about the diode without knowing how long it has to supply the 10 amps. The 4685 will cut the power about 30%.

ronv, thanks for your help. what do you mean by cut the power about 30%?

cheers

The Rds on for the new fet is much lower so the power dissapated in the FET will be lower which should lower its temperature.

If you have to order one look at something like the FDD6637. Its on resistance is only 11 milliohms.

a single 3A diode is probably fine, do you have a filter cap on it?

Thanks for your help guys, as it turns out the inductor definately needed to be larger. 100uH seemed to start to have a good result with the FET now running at a much more healthy 75°C at load. still not ideal but definitely better than it was.