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Question regarding MAX713,712 battery charger controller...

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New Member

Does this seem to be a pretty reliable charger?
im trying to build that circuit for the NiCd or NiMH battery charger. Thing is, i dont want to have to keep exchanging the 713 and 712 chips every time i want to charge a different battery. Is there any way to have both chips in the circuit but use a ON_OFF_ON switch to switch from 713(on) off and 712(on)? Can i do this by simply connecting both chips to the same places but using the switch to change from chip to chip? If so, on which pin should the switch go, on the V+ or...?
here is the chip pinout/datasheet


sorry about all the questions.

thanks in advance,



New Member
in case further info is needed regarding this circuit:

7806 volt reg
9v power source(is this enough or too much or too little?
charging 2- 1.2v AA NiMH or NiCd @ 1800mA.


If you arent too fussy about the enclosure, this is what I would do:

Build 2 pcb's as the design, but make one with the 712 and one with the 713.

Connect the supply to both boards, no need for a switch........ensure the charger supply can supply sufficient power for your requirements, i.e
you need 10v minimum at the minimum charge rate you have selected as determined by the resistors you calculated in the design.......

You could put the pcb's on top of one another.....stacked to minimise case size...heatsink the power transistors too!!

Tell us how you get on 8)


New Member
intriguing idea, i might just do that. Just wondering though, would the switch idea work at all?

and im not fuzzy at all about enclosure, anything will suffice for me.
thx alot again chippie!!!!!!!


ivan :)
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