Is there any IC that could switch ON \ OFF a circuit with an input pin (if i can do both ON and OFF with just one pin awesome!)?
The missing requirement is Switch What?. Without that information your question is "Undefined"
Doc
Docedison:
The missing requirement is Switch What?. Without that information your question is "Undefined"Doc
Atmega + Nokia LCD + SD card + NRF24 wireless module
They will spend something like +/- 100mA i believe
What controls the switch? and for that matter why ? a plain toggle switch could be used. If it must be an electric control what is the voltage and current available from the "Control" pin.
Doc
I'm using 3.7v on the entire circuit.
I can't use a toggle switch because the board can only handle a mini smd push button.
The idea is to save current, but since i'm using a chinese replica of an SMD atmega328, the consumption on sleep mode is still so damn high 
And with that, i can easily switch on and off the entire circuit without having the need to use the atmega itself
An ATmega can power a Nokia LCD and NRF24 wireless module via I/O pins.
The SD card might need 300mA so you'll need a MOSFET for that.
Is it a Pro Mini? Try removing the power LED and voltage regulator. You can get them to sleep at 5 uA.
I have to try an IC just by itself and a crystal.
Btw, do you think that a NE555 will work?
They do make some very small smt slider switches that could probably replace the button.
I don't have time at the moment to draw this out, but you should be able to handle figuring it out. I've thought about it, and it seems like it should work, but someone feel free to point out any flaws.
As for an IC, a decent sized (read: can handle enough current/Voltage) P-Chan MOSFET would do the trick. Basically, you put the MOSFET between your supply (Battery) and Vcc, with a weak pull-up from the gate up to the Supply. Next you wire the button between the gate and ground. Finally, wire an output from the ATmega (with a resistor) to the gate. You program the ATmega that as soon as it gets power, set that pin as a low output.
This will at least handle power on. As for power off, your uC can handle that, though to use the same button, you'll need a DPST switch. You'll have to wire the other side of the switch as an input into the uC and just detect when the switch triggers, and use that input to shut down.
Well all of this components (that i said above) should fit inside of an Nokia 3310, so that's the problem of the switch, i want to use the same push button that comes with it.
Can't i do that P-Chan MOSFET idea with an NPN or PNP transistor?
Sure, you can do it with a PNP, I just like MOSFETs better since they are voltage based instead of current, making them easier for me to think about. You just need to be a bit more careful with the math for your currents.
tsunamy_boy:
I have to try an IC just by itself and a crystal.
Btw, do you think that a NE555 will work?
tsunamy_boy:
Well all of this components (that i said above) should fit inside of an Nokia 3310, so that's the problem of the switch, i want to use the same push button that comes with it.Can't i do that P-Chan MOSFET idea with an NPN or PNP transistor?
You don't need any of that, just send the CPU to sleep and power the other stuff from the I/O pins when it's awake. Use an NPN MOSFET for the SD card because it needs a lot of power.
You may like to take a look at this
Pololu Pushbutton Power Switch LV
fungus:
You don't need any of that, just send the CPU to sleep and power the other stuff from the I/O pins when it's awake. Use an NPN MOSFET for the SD card because it needs a lot of power.
So if i'm using a NPN transistor i need to disconnect the GND of the SD card into the transistor i suppose.
What kind of resistors do you use in this transistor scenario? 10k?
BillHo:
You may like to take a look at thisPololu Pushbutton Power Switch LV
Pololu Pushbutton Power Switch LV (old version)
Thank you, i'll take a close look on that too
BillHo:
Or you can use circuit like this
Great, Thank you so much!! Do you think i can handle +/- 300mA with that schematic?
tsunamy_boy:
fungus:
You don't need any of that, just send the CPU to sleep and power the other stuff from the I/O pins when it's awake. Use an NPN MOSFET for the SD card because it needs a lot of power.So if i'm using a NPN transistor i need to disconnect the GND of the SD card into the transistor i suppose.
Yes.
tsunamy_boy:
BillHo:
Or you can use circuit like thisGreat, Thank you so much!! Do you think i can handle +/- 300mA with that schematic?
The HAT1072H mosfet is the current carrier. It is rated to 40A.
Chagrin:
The HAT1072H mosfet is the current carrier. It is rated to 40A.
Can you point where you see that on the datasheet so i can understand how to choose a mosfet?
(since i don't find that ones on ebay, can i use this instead: http://www.ebay.com/itm/10pcs-SMD-SI230-SI2301DS-MOSFET-Field-Effect-Transistor-SOT-23-/201011688667?pt=LH_DefaultDomain_0&hash=item2ecd3af4db)
I'm working with 3.7v and it should handle at least 300mA (i didn't measure it already but it will be something like this)
You need a P-channel mosfet; you have an N-channel linked.
A quick search for P fets in SOT-23 packages on eBay brings up the AO3401 which is 4A capable (ID), has a VGS(th) (threshold voltage -- when the FET starts to turn on) at -.9V. Figure 2 of the datasheet shows that it's fully on with a VGS around -2.5V; since you're assumedly working in the 0 to 5V (or 3.3V) range that's more than enough to turn it on fully.
Chagrin:
You need a P-channel mosfet; you have an N-channel linked.A quick search for P fets in SOT-23 packages on eBay brings up the AO3401 which is 4A capable (ID), has a VGS(th) (threshold voltage -- when the FET starts to turn on) at -.9V. Figure 2 of the datasheet shows that it's fully on with a VGS around -2.5V; since you're assumedly working in the 0 to 5V (or 3.3V) range that's more than enough to turn it on fully.
Thank you!! Btw, how can you see this "working in the 0 to 5V (or 3.3V) " on the datasheet you gave me, could you please point that out for me?