Building FPGA board

[Altera_Forum]

Ok, Ive made enough progress with my code to get back to my power supply design. 

Question now is, a voltage regulator such as National Semi LM2734Y is listed in a TSOT package, the drawing and description aren't clear if this is something that can be hand soldered to a PCB or a pinhead sized thing, im starting to guess I need to pick another. What is your opinion?  Also the design their toolset gave me showed Vin and Vsupply as two seperate voltage sources, the general info on 2734Y showed one voltage source feeding both pins. If I add a second small battery to my design, will the regulator draw off that if the main 12v suppy runs low automatically, do I have to do something with the "switch" pin, or am I totally misunderstanding what I am doing?

[Altera_Forum]

Here is the data sheet http://cache.national.com/ds/lm/lm2734.pdf and the mechanical drawing is near the end on page 22. The TSOT23-6 is like a thin SOT23 with 3 pins on each side. I solder those type parts with no trouble but you do need a small tip on your iron. 

 Something tells me that you're clueless in the analog world. There is only one pin for power into the chip and then there is one pin (boost) that is used for the gate drive voltage of the internal FET. See page 7 of the data sheet for what is inside of the part and how it works. For any help you'll need to let us know what input power you have to start with and what you need on the output.

[Altera_Forum]

Hello, 

 in case of not knowing how and why with switched-mode power supply, I recommend using the National WEBENCH tools. You define input and output parameters and they tell you which parts to use. You can simply follow the design recommendation and don't need to ask "could I use a resistor instead of an inductor" or "should this pin connected anywhere else".:D  For a first evaluation, I would generally recommend to use linear voltage regulators as far as possible, but I understood from previous forum discussions that you are targetting a battery powered application.   Another possibility would be to copy an existing evaluation board's power supply. As an advantage you can do comparative measurements if your designs behaves unexpected.  By the way, I wouldn't expect power supply to be biggest challenge when creating a new board.  Best reagards and happy developping,  Frank

[Altera_Forum]

Hi eviltwinzzz 

 I just saw in one of your older postings that you were going to use PCB123. I use OrCAD but there is a place I use for prototype boards all the time that gives out a very good PCB CAD program now. After your first board they give you a code that lets you unlock it so you make Gerber files that you can send anywhere instead of being locked to PCB123.  The link is http://www.4pcb.com/ and then go to "tips & Tools" in the top tool bar. Their boards are excellent and you can get 60 sq. in. for $33 each on 2 layer or $66 for 4 layer.  It's always best to check files with a program other then what you made them with. Here is a link to a place that gives out a good Gerber file viewer http://www.lavenir.com/. Click on free downloads.  I also saw a little more about the project being a 12V input. Before you even think of using the lower cost automotive light and noise makers get your hands on some and measure the currents used to drive them. I think you'll be shocked by the high current they use. Standard light bulbs have an inrush current that can be 15 times their normal on current so your drivers would have to handle that. The power with an alternator in a car is not as much of a concern to the car makers as it is with your battery operated unit. On top of that you'll need more expensive parts to drive the high current loads. That might make good LEDs cost less then regular lights in the end.  Do a good tally of just what current every part uses before throwing the dice on your regulators, especially on thinking of linear regulators. A couple of hundred milliamps at 1.2V can add a lot of loss from 3.3V.  If you give me or point me to more info on your project I can maybe help with the stuff outside the Cyclone part because analog is what I like best.  Enjoy,  Al

[Altera_Forum]

Thanks for info eewizard, your answer was exactly what I was looking for, I purchased a Weller WES51 iron before I even stared this project, I was advised it might make things easier in the long run. You are correct I am in the infancy of this project, with much more info to collect.  

 Here is a little background. It will be a 2 peice "laser tag" kind of game, with a stationary target, I know people who play paintball, I don't actually play. The board will be a in a big RPG style "launcher" I will make out of PVC that will fire a small Laser LED to the target, with the FPGA controlling how often it can be fired how many times over a length of time, they can make it parts of the paintball games they play. An advanced version may roughly measure distance with a GPS chip  My idea is the FPGA will activate Optical relays driving the 12v lights and siren for noise for a breif moment directly from the battery, the regulators will make my lower voltages to drive just the FPGA from the same 12v battery source. A similar system on the "target" with a Laser detector (unknown type) will make noise and lights if a hit is made.  Plan B is to isolate the FPGA by running it off a second power source, like a cell phone battery, using the relays to drive the lights and siren off the first 12v source.  This is a fun/game/hobby project for me, I have no deadline, no boss, just fun.  I've been through the WEBENCH process and found it helpful, Ive invested enough hours in pcb123 to stick with it for now.

[Altera_Forum]

Hi eviltwinzzz 

 Most all of my work is not an Altera part , DSP, or a micro like a PIC chip. The big part, other then software, is interfacing the "Smarts" to the outside (analog) world. If you do the PCB right you can forget the opto couplers and especially the relays. Those are both expensive part types and the drive for a relay may as well just drive a light or something that makes sound. Bypass caps and grounding make all the difference in the world.  As far as the GPS goes ... what kind of distance do you want to measure? 10 feet, 50 feet, or across a football field? If it's close you might look at an ultrasonic range finder at a fraction of the trouble getting GPS going as well as lower cost.  To be honest, for just controlling shot count and timing probably all you need is a $3 PIC chip instead of a Cyclone and configuration chip.  Instead of a LASER you can modulate an IR led and have a detector tuned for the modulation frequency. That is what is often used to detect someone standing in a door.  Last but not least, what is your expected production volume? For a low number use expensive things that save time but higher numbers you trade the other way.  Al

[Altera_Forum]

Good question, low low volume, It's not my full time job (sales/accounting), I am planning on building these by hand one at a time after I finish my regular jobs and family time. I am going to put the third or fourth one on EBAY and see what happens, if the buyer likes it I will keep building them. 

 I picked FPGAs to put that on my resume someday and because I did my thesis using Altera 5064 FPGAs for a car alarm a long time ago. I have done some reading on PIC chips and find they might fit some other projects I have drawn in my notebook.   The GPS chip part, I was planning to measure distance to target within 25foot intervals, so you can balance team strength. Lets say the attacking team has better shooters then the defending team, force them to get within 50 feet to fire. If the opposite is true let them shoot from 200feet.  Mucho Mucho thanks for having this discussion with me, I have no resources around me to draw on since my career is in other fields. I can probably ask you a million questions.  Frank is right, power was a small speedbump on the project and I am ready to move onto next challenge.

[Altera_Forum]

The million questions is Ok with me but should probably not continue on this thread as it will get far away from Altera so start using private msg by clicking my tag eewizard7. 

 Al