I'd like to recreate the standard Arduino regulator circuit on a breadboard and would like a little guidance.
Reason is, I've been happily creating a few 'Arduino's on a breadboard' with good success in subsequently transferring them into sculptural work (using SMD components/etching of boards). However, as my current values have increased, I have (not surprisingly) found my usual SMD 5vdc LDO reg http://www.mouser.com/Search/ProductDetail.aspx?R=TLV1117-50IDCYRvirtualkey59500000virtualkey595-TLV1117-50IDCYR getting too hot and shutting down as I think its junction temp gets too hot from the increased current flow (from reading grumpy_mike's power tutorials think I understood this could be the reason for the circuit shutting down after the reg gets hot (3 minutes, then off it goes).
Also, from what I've read, I could consider using a switching regulator for better efficiency. I did notice though, that the same project that overheats works fine with a standard Arduino shop Diecimila. A look at the Arduino 2009 schematic for power in shows a => power in jack, a zener diode (I think), a 100 u cap (micro farads?), a 100 n cap (nano farads?), the MC33269D-5.0 volt regulator http://www1.mouser.com/Search/ProductDetail.aspx?qs=dFKnUM%2FquJZ0YuZ%252b66PKCA%3D%3Dand a final 100 u cap. The current rating for both regulators is the same at 800 mA output, the Maximum Operating Temperature is the same at 125 deg celsius, but the Arduino's regulator has max input voltage as 20, while the one I use is 15 volts. Is this the main difference as to why one regulator shuts off and the other is OK and just warm to the touch? an extra possible 5 volt 'allowance' - so I might use this new regulator -or am I (as I suspect) missing the point?
Any idea what your current requirements are? And what is your input voltage? My first thought would just be a simple old garden-variety 7805 in a TO-220 package, with a heat sink if needed. Correct on microfarads and nanofarads, probably not a Zener diode, just an ordinary rectifier to protect against reverse polarity power being connected.
Heat dissipated by a linear regulator is simply the voltage dropped across it times the current flowing through it, and should be darned near the same for any regulator, all else being equal. The max input voltage rating doesn't come into that equation.
Heat dissipated by a linear regulator is simply the voltage dropped across it times the current flowing through it, and should be darned near the same for any regulator, all else being equal. The max input voltage rating doesn't come into that equation.
OK, thanks. I did wonder if there was something about the setup on the Arduino board hooked up to the regulator part of the circuit that was allowing better heat dissipation. Perhaps it was that quality that allowed operation of the whole circuit to continue - (I didn't specify input voltage or current requirements as I no longer have the circuit, but ~12.5 VDC probably un-regulated and about 600-700 mA - guessing this one) However, as exactly the same current requirements and input voltage was used in each case (i.e. it was the same circuit excepting that I transferred the 2 wall transformer power wires from the areadboard & assoc reg/caps part of it over to the arduino and hooked the outputs up to the Arduino pins instead of the holes in the Bboard. So I thought perhaps the Ardiunos reg was more efficient... so perhaps putting in a TO-220 package in place will allow for better heat loss?
If you want to use a switching regulator, I recommend using a pre-packaged unit like these:
Thanks! good to know and I think I'll try this option for experiments too.
Rich.
Most assuredly. TO-220 was designed for higher-power and good heat dissipation using the tab on the package. That little SMD regulator on the Arduino board is not really sufficient for much more the Arduino load itself, and that only for very modest input voltages (<12V)
So this is good to know also and I'll be planning that for my 12 volt circuits or a switching reg (as the circuit I had built above was for a) running a trimmed/cut common anode 12v RGB led strip (with about 10 side by side singular led modules in total) and b) the home-etched Arduino.
Thanks CrossRoads for the link to that unit - delivers a good whack of current! I'll have a look around that site generally too.
Most assuredly. TO-220 was designed for higher-power and good heat dissipation using the tab on the package. That little SMD regulator on the Arduino board is not really sufficient for much more the Arduino load itself, and that only for very modest input voltages (<12V)
So this is good to know also and I'll be planning that for my 12 volt circuits or a switching reg (as the circuit I had built above was for a) running a trimmed/cut common anode 12v RGB led strip (with about 10 side by side singular led modules in total) and b) the home-etched Arduino.
Thanks CrossRoads for the link to that unit - delivers a good whack of current! I'll have a look around that site generally too.
Cheers,
Rich
You might also also want to look into the TO-3 cased 7805 (though its much more bulky, harder to connect to, and the heatsinks/hardware start to get expensive if you buy new)...
You might also also want to look into the TO-3 cased 7805
Thanks cr0sh, will check it out, although as you mention, the package is bulky and the component's aesthetics play a large role in the work I'm making, as I seek to include the components actually as part of the design itself...
Speaking of electronic sites, I've had good deals direct from Hungzhou factories in China, esp long (15-30 feet), silicon encased RGB LED strips and have a personal contact there if anyone is interested.
R
