Switching voltage inputs with a chip

I have a small project I'm working on that uses rechargeable batteries.  However I want the device to stop drawing from the batteries whenever an external power source is plugged in.  (The external power source would then power the internal battery charger and the main device.)  Is there a chip or circuit that could be used for this?  My only alternative is to modify the power supply port to include a micro spdt that will switch when plugged in.  But I'd rather like to avoid that.

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chrisadam7 years ago
The switching regulator is increasing in popularity because it offers the advantages of higher power conversion efficiency and increased design flexibility (multiple output voltages of different polarities can be generated from a single input voltage). This paper will detail the operating principles of the four most commonly used switching converter types: Buck: used the reduce a DC voltage to a lower DC voltage. Boost: provides an output voltage that is higher than the input. Buck-Boost (invert): an output voltage is generated opposite in polarity to the input. Flyback: an output voltage that is less than or greater than the input can be generated, as well as multiple outputs. Also, some multiple-transistor converter topologies will be presented: Push-Pull: A two-transistor converter that is especially efficient at low input voltages. Half-Bridge: A two-transistor converter used in many off-line applications. Full-Bridge: A four-transistor converter (usually used in off-line designs) that can generate the highest output power of all the types listed. Application information will be provided along with circuit examples that illustrate some applications of Buck, Boost, and Flyback regulators. ______________________________________________________ Want to get-on Google's first page and loads of traffic to our website? Hire a SEO Specialist from Ocean Groups[url=http://oceangroups.org/] seo pecialist [/url]
stalledaction (author)  chrisadam7 years ago
Spam, really?
stalledaction (author) 7 years ago
Both of those are awesome ideas, and save me wiring! And space more importantly! I forgot about the headphone jack. Thanks so much!
stalledaction (author)  stalledaction7 years ago
Had a thought though, wont the negative lead (or positive, whichever one I had switching) of the batteries that is attached to the charger complete the circuit? (based off your instructable instructions kelseymh, but I suppose the same would go for the headphone jack. Having the charger IN the system kinda changes things. My guess that both leads for the battery to the system would have to be switched off. In which case, I'd need a DC Jack with DPDT switch. 6 leads? System in center, batteries on side with unplug, charger on side with plug in. Is there such a thing?
NachoMahma7 years ago
. Many headphone jacks have a switch on the end that the plug actuates when inserted. Same basic principle as the part kelseymh mentioned and (usually) easier to find.
kelseymh7 years ago
You don't need a chip, just a three-lead jack for the power adapter. For my own projects, I used RadioShack's 274-1582, Size M panel-mount socket with switch. It works by having a small lever switch that is pushed out out of the way when you plug in the adapter. With appropriate wiring, you can have your device switch between the external power vs. internal batteries, just by unplugging the jack.