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Power on / off for a portable battery edeviece

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wolf69

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Hi all!
I have to design a portable device powered by a 9V battery.
I'd like to simply power on and off with a push button and when powered off the battery be diconnected.... any good Idea?
In the device there is a uC (cypress psoc), I could use some line for this porpouse....

Bye!
 

solvarg

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wolf69 said:
Hi all!
I have to design a portable device powered by a 9V battery.
I'd like to simply power on and off with a push button and when powered off the battery be diconnected.... any good Idea?
In the device there is a uC (cypress psoc), I could use some line for this porpouse....

Bye!
The MAX1614 drives high-side, N-channel power MOSFETs to provide battery power-switching functions in portable equipment.
Why cant you use a elektro mechanical switch?

Regards
 

wolf69

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the switch is a solution but is quiete complex mecanichally to use; has a shorter life than a push button; it is more difficult to protect from dust thana push button.
The max1614 uses 6uA... but maybe is okay.
Thank you solvarg!
 

bobcat1

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Simply use a Mosfet !!!

You can use a logic mosfet like BS170 shorted by pushbutten switch
on the main +V of the processor

When you push the button it's connect the +v line to the processor
when the processsor go's out of reset and start the program is set the
I/O connected to the Mosfet gate (via 10 K resistor ) to +V potential

and the mosfet conduct and continue to supply +V to the processor

when you want to shut down all you have to do is to set the I/O
to 0V the mosfet will stop to conduct and the circuit shutdown


Hope it's help


BoBy
 

flatulent

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leakage current

Be ware of the leakage current of any semiconductor switch you use. The capacity of these batteries is 400 mAHr. 45 microamps of leakage will totally discharge one in a year.
 

wolf69

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thank you sirs!
I just designed bobcat1's circuit with a little improvement: I use the push button to turn on the uC by the mosfet and I can still read its state so when the user push it for a time (I turn off the lcd) and then, when leave the push button, uC power down itself and the entire circuit.
Wolf
 

wolf69

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leakage current should be 100nA (using irfu9024, by internetional rectifier)
;)
 

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