ON/OFF pushbutton circuit for battery powered device - Electronic Circuits Projects Diagrams Free

Andy_123 · 5th May 2007, 12:47 AM

Not sure if this forum is the best place for this post, just let me know if I should move it

I am making a PIC based device that uses +5V for PIC and +3.3V for some other circuits.
Power coming from two AA batteries converted to +5V and +3.3V using TPS60120 and TPS60140.

What I need is ON/OFF switch using one (on/off) or two (on and off) pushbuttons.
Slider on/off switch is not an option, I need pushbuttons

Something like:
- ON button brings power to PIC,
- PIC bypasses ON switch, seals it
- PIC will shut device down once OFF button held for 5 seconds or no activity for a 2 minutes.

It would be better if I can make it with one button.

Can TPS's enable input be used?

Any other ICs?
Battery gives only 1.8-2.6V and any voltage drop is costly.

HarveyH42 · 5th May 2007, 01:09 AM

Don't no much about PIC, and just a beginner with AVR, but seems like this could be done with an plain SPST pushbutton, SLEEP MODE, and a Pin Change Interupt. Not sure if your PIC has these features, but $1.16, 8-pin ATTiny13L does, and current draw in Power-Down sleep mode is very low, <0.1 uA at 1.8 volts.

Andy_123 · 5th May 2007, 01:13 AM

I was looking at sleep mode, but I don't really want to keep these charge pumps running. At least I need to keep +5V running and this will drain battery I guess...

Andy_123 · 5th May 2007, 01:57 AM

I probably needs something like this
http://www.linear.com/pc/productDeta...3,C1144,P10330

or event better, because no extra ICs needed:
http://www.maxim-ic.com/appnotes.cfm/an_pk/3283
I can implement this one with TPS60140 and 2 diodes instead of "OR"

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5th May 2007, 12:47 AM	(permalink)
Andy_123	ON/OFF pushbutton circuit for battery powered device Not sure if this forum is the best place for this post, just let me know if I should move it I am making a PIC based device that uses +5V for PIC and +3.3V for some other circuits. Power coming from two AA batteries converted to +5V and +3.3V using TPS60120 and TPS60140. What I need is ON/OFF switch using one (on/off) or two (on and off) pushbuttons. Slider on/off switch is not an option, I need pushbuttons Something like: - ON button brings power to PIC, - PIC bypasses ON switch, seals it - PIC will shut device down once OFF button held for 5 seconds or no activity for a 2 minutes. It would be better if I can make it with one button. Can TPS's enable input be used? Any other ICs? Battery gives only 1.8-2.6V and any voltage drop is costly.

5th May 2007, 01:09 AM	(permalink)
HarveyH42	Don't no much about PIC, and just a beginner with AVR, but seems like this could be done with an plain SPST pushbutton, SLEEP MODE, and a Pin Change Interupt. Not sure if your PIC has these features, but $1.16, 8-pin ATTiny13L does, and current draw in Power-Down sleep mode is very low, <0.1 uA at 1.8 volts.

5th May 2007, 01:13 AM	(permalink)
Andy_123	I was looking at sleep mode, but I don't really want to keep these charge pumps running. At least I need to keep +5V running and this will drain battery I guess...

5th May 2007, 01:57 AM	(permalink)
Andy_123	I probably needs something like this http://www.linear.com/pc/productDeta...3,C1144,P10330 or event better, because no extra ICs needed: http://www.maxim-ic.com/appnotes.cfm/an_pk/3283 I can implement this one with TPS60140 and 2 diodes instead of "OR"