Several people have sent me offline emails asking how I connected my PT6302A regulator to my system. I am sending this reply to list so it can make it into the archives ... Patrick Bennet wrote: > I believe you said you used a pt6302a ISR Yes. > The only problem is after reading various faqs > and tutorials on how to use the chip, I still > am confused, and unwilling to proceed as such, > not wanting to fry my new board... Hookup is easy (see below). If you use a multimeter (voltmeter) to test the output voltage before hooking up to your board you shouldn't be concerned about frying anything. If you don't have a multimeter, get one now and always use it whenever you add or change power wiring. > I have been told I need a 100 uf Resistor. No, it's a capacitor not resistor. According to the PT6302A data sheet it should be a 100uF Electrolytic Capacitor. You can find these at Radio Shack or any electronics components shop. You can order both the PT6302A and 100uF capacitor in single quantity from Digikey (http://www.digikey.com/) > Is this all I need? Yes. The only other parts I use are banana jacks for hooking up the power source (highly recommended), and I also mount the regulator on "soldered breadboard" to make the wire connections easy and solid. Soldered breadboards are laid out like the plastic (temporary prototyping) breadboards but they are thin metal and are made to permanently solder components on the board. I use these for the regulator and for microcontroller circuitry on my wearable. I highly recommend them. > Steve Mann suggested being "paranoid" and adding > electrolytic capacitators and the works According to the PT6302A datasheet the 100uF cap is required, not optional. I noticed that Steve does a bunch of redundant connections, but these are not really necessary. > but I'm looking for safe and simple...just enough. All you need is the PT6302A and one 100uF electrolytic capacitor. Using the permanent (soldered) breadboard material makes soldering wires much easier since you solder onto the board instead of onto the regulator pins. Banana jacks have proved to be reliable for connecting power sources to the system. > How can I determined exactly what I need to do to > get my 5v @ 1.5a avg for my 5822 using this chip The regulator will produce the 5 volts, but it has nothing to do with the current draw, that depends on what other peripherals are attached and how much load is on the CPU etc. Keep in mind that the 1.5A average is for the CPU board only, your total amount will be a lot more when you add on the HDD and other peripherals. > Whatever specifics you can provide me would be > greatly appreciated First take a look at the PT6302 data sheet at http://www-s.ti.com/sc/psheets/slts031b/slts031b.pdf You will see the following pinouts in the data sheet: 1) Inhibit 2) Vin 3) Vin 4) Vin 5) GND 6) GND 7) GND 8) GND 9) Vout 10) Vout 11) Vout 12) VoutAdj You are only concerned with the Vin, GND, and Vout pins. Ignore the Inhibit and VoutAdj pins because they are for adjusting the voltage to something other than 5 volts. You will notice that there are multiple pins for each of Vin, GND, and Vout. You only need to connect to one of each of these, but it won't hurt to attach to all of them (like Steve recommends). On my system I am only connecting to one of each of these. Take a look at the "standard application" schematic on the PT6302A data sheet. Since you only need 5 volt output (not adjustable voltages) you should ignore the VoutAdj, INH, and Q3 parts in the diagram. The diagram also shows an optional 1uF capacitor between Vin and COM (ground) but I am not using this. If you ignore these parts that are not applicable for 5 volt only operation, you will see that there isn't much to hooking this up: 1) The positive lead from your power source (Vin) connects to any of the Vin pins (2,3,4) on the PT6302A regulator. 2) The negative lead from your power source (COM) connects to any of the COM pins (5,6,7,8) on the PT6302A regulator, and also passes directly to the board as the ground lead. 3) You will see that the schematic shows item C2 (100uF electrolytic capacitor) connecting between the Vout pins (9,10,11) and COM (ground) signals. The positive lead on the capacitor (always the longer of the two leads) connects to Vout and the negative (shorter) lead connects to COM (ground). 4) Before you attach the CPU board, test the output voltage with a voltmeter. The red (positive) probe on the voltmeter connects to Vout and the black (negative) probe connects to COM (ground). It should read within +/- 0.05 of 5 volts. 5) If you are getting 5 volts, you are done, just connect the Vout and common to your board. Don't ever skip step number 4! > I also wanted the ability to run from a power outlet > (I don't need charging however), I don't believe that > the pt6302a can handle this voltage, can it? No! The PT603A is 9-30 volts DC input with 5 volt DC output. It is NOT and AC/DC adapter. What you need is an AC/DC adapter to plug into the PT6302A. > If not...what would you suggest? Do I need to make a > whole nother power supply? Don't make one, just buy an off-the-shelf AC/DC adapter. Note that you need high amperage (approx 2.5 amps), most of the adapters you will see on the shelf aren't anywhere near high enough amperage (most are 300 or 500 or 800 mA). I am using a 2.5 amp 12 volt AC/DC adapter. I got mine from EMJ embedded who sourced it from Parvus. But there are many other sources for these. I chopped off the plug on the adapter and replaced it with banana jacks. Make sure you do the voltmeter test before attaching! I have multiple adapters so I can have one at home and at work or wherever and just plug in the wearable. The AC/DC adapters are cheap. The other thing I did was buy a cigarette lighter plug with cable from Radio shack and put banana jacks on the end so I can run from my auto power system. You don't need (or want) a cigarette lighter cord with a power adapter, just the plug and wire. Your vehicle power system is already acceptable voltage and amperage to hook directly up to the PT6302A regulator. > I'm very anxious to have all the parts I need so I > can play with it over Christmas... If you order the PT6302A and 100uF capacitor from Digikey you should have it within a couple of days. Try to find some permanent breadboard material (I got mine at Fry's electronics), some banana plugs and jacks, and a cigarette lighter plug with cord (got mine at Radio Shack). If you don't have a multimeter (or voltmeter) now is the time ... Happy Wearing Doug ------------------------------------------------------------ Grow your own Wearables: http://wearables.los-gatos.net What I'd like is to have you call me and my jacket answers ------------------------------------------------------------ -- Subscription/unsubscription/info requests: send e-mail with subject of "subscribe", "unsubscribe", or "info" toWear-Hard Mailing List Archive (searchable): http://wearables.blu.org please, Please, *PLEASE* don't subscribe through a forward/false domain
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