Power supply recommendation please?
Rforbes
Posts: 281
Hey all,
I'm having a difficult time finding a power supply. Can you please let me know if you know of a specific make/model with the following parameters?
Voltage supply- 120 to 240 VAC, 60 Hz (85-264 VAC is fine, or anything else that works with 120 or 240)
Voltage out- 5vdc or 3.3, or both.
package type- pcb mount or pcb mounted with a tiny foot print (lesss than 3" long, 2" wide, 1" tall)- preferably a little guy I can solder onto a bread board.
5 to 10 watts output power
Linear or switch mode- if switch mode, 500kHz or higher (for meeting recommended switching frequency of the new Xbee HP model)
Efficiency is not important.
Power factor is not important.
I've found several with lower switching frequencies (67khz through 132 khz) but I'm not sure if these will cause problems for the Xbee. So I'd like to stick with 500kHz-1mHz if possible.
Thoughts, advice, etc are appreciated. Thanks in advance!
Robert
I'm having a difficult time finding a power supply. Can you please let me know if you know of a specific make/model with the following parameters?
Voltage supply- 120 to 240 VAC, 60 Hz (85-264 VAC is fine, or anything else that works with 120 or 240)
Voltage out- 5vdc or 3.3, or both.
package type- pcb mount or pcb mounted with a tiny foot print (lesss than 3" long, 2" wide, 1" tall)- preferably a little guy I can solder onto a bread board.
5 to 10 watts output power
Linear or switch mode- if switch mode, 500kHz or higher (for meeting recommended switching frequency of the new Xbee HP model)
Efficiency is not important.
Power factor is not important.
I've found several with lower switching frequencies (67khz through 132 khz) but I'm not sure if these will cause problems for the Xbee. So I'd like to stick with 500kHz-1mHz if possible.
Thoughts, advice, etc are appreciated. Thanks in advance!
Robert
Comments
Hmmm, that's a pretty broad set of specs, but my initial thoughts would be an amply sized wall-wart fed to linear regs for 3.3 and 5 volts. Well bypassed with a variety of caps it's output would be very clean. You may need some heat-sinking, though the classic LM style are pretty bullet-proof.
There are dozens of options, this is quick and easy and can be constructed quickly with Radio Shack parts.
I probably should have been more clear as to my concern. I have found a good open frame and pcb mount SMPS meeting the specs I've laid out with the exception of the switching frequency. 500 kHz or greater is what I'm trying to find, with no luck yet. As long as it's 3.3 or 5v out, low ripple/noise (less than 200mv p-p), and accepts either 120VAC or 240VAC it'll do the job. But if I can get one that meets the 500 kHz switching frequency as well, that would be great.
I'm actually not sure why the Xbee HP recommends such a high switching frequency. I don't quite understand how this can impact everything. I'm sure it can, but I lack the proper understanding of exactly how/what can happen if I keep using a much lower switching frequency.
Err ? you expect to solder MAINS voltage on a Bread Board ?
Usually, products seek to take MAINS out of the case, rather than include it.
The Global Cell Phone standard is now for Micro USB as the Power/Charging connector, tho many use Std size on the charger end.
So I would follow that standard, and use a USB style connector for power, and take the mains off the end product.
In general, anything connected to MAINS is subject to a lot more inspection and protection. Thus, you will likely find only UL approved wall warts or UL approved caged switcher supplies that go from MAINS to the target supply voltage. Manufacturers are no longer selling items directly to the public in small quantities that might be a significant liabillity due to shock or fire.
Jameco is quite typical of what is available new.
http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?langId=-1&storeId=10001&catalogId=10001&categoryName=category_root&subCategoryName=Power Supplies %26 Wall Adapters&category=45
But you might be able to find something old and odd on Ebay, at Electronic Surplus, or Electronic Goldmine.
Personally, I have had enough joltz from exposed mains in my life time and am happy to NOT have any chance of brushing againts 120VAC while working with bench work.
The Xbee is a radio frequency device that may experience problems if the switching supply frequency is a harmonic of the carrier frequency that it uses for transmissions.
I am guessing that if the switching frequency is not as high as you like it, the RFI still may not be an issue. Why? Well, it is caged.. and there are other factors reducing the noise.
You might as Xbee to clarify there specification and offer alternative solutions.
Xbee may even know of a particular board supplier that they prefer. They do say 500khz, but the ripple is much lower on these than the level they specify. For $12 USD new, it is not much risk to try. Look on a scope for the actual output.
http://www.jameco.com/Jameco/Products/ProdDS/1919043.pdf
@jmg- The reason I'm looking for this type of power supply is for experimentation purposes. I get what you're saying though! Thanks for the input
@Loopy- Thanks much! That's the highest sw. freq I've come across so far.
Get a 2amp USB charger (eg 10watt), use a heavy duty regular-usb/micro-usb cord.
http://www.newegg.com/Product/Product.aspx?Item=75-984-918&ParentOnly=1&IsVirtualParent=1
But if you insist of bringing dangerous high voltages to your board:
http://www.mouser.com/Power/Power-Supplies/Linear-and-Switching-Power-Supplies/_/N-axgkhZscv7?P=1z0wda4Z1z0wdi2Z1z0wda9Z1z0wdi1Z1z0wda5Z1z0wcq8Z1z0wbnbZ1z0wcieZ1z0wda0Z1z0wd9qZ1z0wcrcZ1z0wc8xZ1z0wcqgZ1z0wcevZ1yzxpgwZ1z0wd77Z1z0wd9k&Ns=Pricing%7c0
Personally, I feel that Xbee may have published an overly cautious spec for some reason. But the lower the supply voltage (3.3v) and the lower the ripple voltage, the easier to may a low pass filter and resolve the problem... if there is any ... on your own.
Good luck.
I don't think you will have to actually solder the power supply to your board. If does have some threaded mounting screw holes.