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#1
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1 Amp DC/DC Converter Chip?
I want to build a 5 Volt power suppply to run my PDA in my
glider from the 12 volt battery. Sometimes I use a 14 volt battery too, so it needs some input voltage range. I'm looking for suggestions and a DigiKey part number for a suitable 1 amp DC/DC integrated power supply chip. I'd like: at least 80% efficient no radio noise Vin of 10.5 to 16.5 volts Vout 5 volts 1 amp low cost I've looked at the LM2825 and the LTC1174-5, but I'd like to hear from anyone who's done this. Thanks |
#2
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"bcjames" wrote in message ... I want to build a 5 Volt power suppply to run my PDA in my glider from the 12 volt battery. Sometimes I use a 14 volt battery too, so it needs some input voltage range. I'm looking for suggestions and a DigiKey part number for a suitable 1 amp DC/DC integrated power supply chip. I'd like: at least 80% efficient no radio noise Vin of 10.5 to 16.5 volts Vout 5 volts 1 amp low cost I've looked at the LM2825 and the LTC1174-5, but I'd like to hear from anyone who's done this. Thanks Well, good luck. Anything that is 80% efficient and low cost is going to have some RF noise. You might look on the National Semiconductor website. They have an online design tool using their parts -- it gives you a circuit and a parts list. For some additional cost, they'll ship you a PC board and the parts. Tim Ward |
#3
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bcjames wrote:
I want to build a 5 Volt power suppply to run my PDA in my glider from the 12 volt battery. Sometimes I use a 14 volt battery too, so it needs some input voltage range. I'm looking for suggestions and a DigiKey part number for a suitable 1 amp DC/DC integrated power supply chip. I'd like: at least 80% efficient no radio noise Vin of 10.5 to 16.5 volts Vout 5 volts 1 amp low cost I've looked at the LM2825 and the LTC1174-5, but I'd like to hear from anyone who's done this. Thanks Check out Maxim, they tend to be very helpful with samples. They also have parts with ring damping circuitry which would help with the radiated noise. Another option is to download LTSpice ( http://www.linear.com/software/ ). That software has a switcher designer wizzard, you enter your parameters and it spits out a circuit you can simulate. Depending on your experience and amount of effort you want to spend, it may be worthwile to look into DC-DC converter modules. Kind regards, Iwo |
#4
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Use a switch mode or buck regulator. Input range at least from 10-14 volts, go
with fixed output 5V. I build one last year using a chip and a few passives thrown on a circuit board. Pretty easy. I'd have to dig in the ship, though, to get the Part Number. Just Google away...many good options from Maxim, etc. Explore Digikey and others to get all the parts together. Radio Shack won't suffice. Contact me directly for more help. Alternatively, you might find an evaluation kit or an off-the-shell solution like from http://www.soarmn.com/cumulus/ I chose to build my own because I learned a new gizmo! Plus, many years ago I learned which end of a soldering iron to hold...took a few tries ;-) Jim Vincent N483SZ illspam |
#5
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http://www.internationalsoaring.org/78hc205.pdf
Needs some attention to good ground circuit, input filter and screening but work very well - 10 - 30 volt input, 2 amp output. Ian |
#6
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bcjames wrote in message . ..
I want to build a 5 Volt power suppply to run my PDA in my glider from the 12 volt battery. Sometimes I use a 14 volt battery too, so it needs some input voltage range. I'm looking for suggestions and a DigiKey part number for a suitable 1 amp DC/DC integrated power supply chip. I'd like: at least 80% efficient no radio noise Vin of 10.5 to 16.5 volts Vout 5 volts 1 amp low cost I've looked at the LM2825 and the LTC1174-5, but I'd like to hear from anyone who's done this. Thanks Hi; Have a look at the TI integrated switching regulators. This part and a couple of capacitors will be all you need. http://dkc3.digikey.com/PDF/T043/1317.pdf Here is an app note for use in a car: http://focus.ti.com/lit/an/slta010a/slta010a.pdf These are nice overload protected parts and will get you going pretty quickly. Scott |
#7
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Here's an easy approach. Go to
http://www.national.com/store/view_i...LM2675-5.0EVAL order the National Semiconductor LM2675 demo board ($8!). All you have to do is wire input voltage and output voltage (5v, 1A) to the board. It is @ 90% efficient. I have been using this converter for my Ipaq this season and it works great. No RFI that I can tell. Good luck. "bcjames" wrote in message ... I want to build a 5 Volt power suppply to run my PDA in my glider from the 12 volt battery. Sometimes I use a 14 volt battery too, so it needs some input voltage range. I'm looking for suggestions and a DigiKey part number for a suitable 1 amp DC/DC integrated power supply chip. I'd like: at least 80% efficient no radio noise Vin of 10.5 to 16.5 volts Vout 5 volts 1 amp low cost I've looked at the LM2825 and the LTC1174-5, but I'd like to hear from anyone who's done this. Thanks |
#8
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Radio Shack sells numerous solid state voltage regulators for pennies.
Easy to use and wire for your requirements. GHamilton N7409J |
#9
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The Radio Shack regulators are very inefficient. If you need 5 volts and
run 13 volts input, the 8 volt drop represents total loss. Total power loss is determined by multiplying the 8 volt drop by the current draw. When battery power is precious, it is better to use a converter chip to actually convert the 13 volts to 5 volts - at over 80% efficiency. The few extra dollars paid to purchase a converter rather than a voltage dropping regulator is paid back over the life of the equipment. Colin N12US --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.742 / Virus Database: 495 - Release Date: 8/19/04 |
#10
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COLIN LAMB wrote:
The Radio Shack regulators are very inefficient. If you need 5 volts and run 13 volts input, the 8 volt drop represents total loss. Total power loss is determined by multiplying the 8 volt drop by the current draw. When battery power is precious, it is better to use a converter chip to actually convert the 13 volts to 5 volts - at over 80% efficiency. The few extra dollars paid to purchase a converter rather than a voltage dropping regulator is paid back over the life of the equipment. Colin N12US --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.742 / Virus Database: 495 - Release Date: 8/19/04 To elaborate on what Colin said: to provide 700 milliamp charging current to the Ipaq, your 12 volt battery must supply: * Radio Shack voltage regulator at 12 volts: 700 milliamps at 14 volts: 700 milliamps * 80% efficient switching regulator at 12 volts: 360 milliamps at 14 volts: 310 milliamps My 3835 Ipaq can draw over 900 milliamps while charging and running a program; my 2215 can draw abut 700 milliamps. It does drop off by about 50% when fully charged. -- Change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
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