Linear Tech demo board helps you compensate switching power supplies
Paul Rako - November 18, 2011
One of the benefits of hanging out with a bunch of former Linear Technology FAEs is that you find out about neat little demo boards like the one in this picture.
It is a tiny RC decade box you can use to tune in the loop response of your switching regulators. It must be expensive to make so you can expect to pay a few bucks for it, hang on…. Yeah, it is not even listed in the demo boards on LT’s web site. This is a Lab Board- a tippy top secret board that is clearly marked “For Linear technology customers only”. So you can’t buy it, but if you know an LT FAE (field application engineer) and you have bought a few thousand LT parts, maybe he can scrounge one up for you. Then again, if enough people contact LT asking to buy the board, what do you figure? 20 bucks? Is that fair? Well if enough people try to buy it, maybe LT will put it on their demo board page. Don’t gripe if they don’t, hardly any of the demo boards from any analog manufacturer are a profit deal. So even 20 bucks may not be enough just to pay for the parts and assembly and hassle for a board like this.
Speaking of former LT FAEs, I had lunch with my buddy John “wild man” Dutra. He is over at Maxim now. We go way back, to my HP consulting days, and I was hooking Jon up with another pal, John Haggis, who needed some analog boost converter help. Jon showed John a great little trick popularized by Linear Technology founder Bob Dobkin. If you have a current-mode boost converter, there is a comp pin on it. That comp pin is the node between the feedback transconductance amplifier, which has a current output, and the current feedback comparator that regulates the current thought the inductor and switch. What Jon pointed out was that you can hang a transistor or opto or some other device on that comp pin, and when you pull current out of it, you can regulate or shutdown the loop. It’s a handy safe handle on any switching regulator IC with a comp pin that is feed with a current.
Since I have been going through my hard dive lately, I found a few nice pictures.
My buddy Jon Dutra is a real power supply design whiz. He is the go-to guy for your power problems.
Here is my long-time pal John Haggis, who Dutra was helping with a boost converter design.
And not to neglect Bob Dobkin, here are some snaps from my hard drive, I suspect taken under the auspices of John Hamburger, the PR director at LT.