I'm working on a "robot unicorn" for my 5yo daughter. I've got most things figured out, but need to do some work to keep battery consumption reasonable. (Significant: In the end, this is a kid's toy. I want to design it well, but it doesn't merit exotic efforts or expenses to attain "perfect". A $4 good-enough circuit trumps a $100 awesomely efficient super-circuit)
The module I'm struggling with is the "switch" between the battery and the rest of the electronics. The behavior I am trying to achieve is essentially, a bistable multivibrator:
Bonus question:
I'm also letting the micro-controller control power to various sub-systems. (E.G. Turn off power to the audio amplifier when no sound effects are being played to prevent wasting the battery) Is there anything better than a simple NPN transistor as a switch? (Better = lower battery drain with similar simplicity)
The module I'm struggling with is the "switch" between the battery and the rest of the electronics. The behavior I am trying to achieve is essentially, a bistable multivibrator:
- Initially off/open. It is important that battery drain is really, really low in this state so the battery isn't wasted while the toy is off.
- When an "ON" input goes high, voltage should flow freely from "Battery In" (+11.1V) to "Main Power Out" (This will power on the microcontroller that will handle everything from there) This would be a stable state. (Power continues after the "ON" input goes low.)
- When an "Off" input goes high (>2V) , "Main Power Out" goes off. (This is to allow the micro controller to send the power off command to shut everything down.)
- Repeat
- The circuit needs to be designed for reasonably low battery consumption, with the lowest usage in the "Off" state.
- Way too much power consumption for a battery powered device.
- Not suitable for high side switching
- Designed for much higher loads than I need (excessive components and complexity)
Bonus question:
I'm also letting the micro-controller control power to various sub-systems. (E.G. Turn off power to the audio amplifier when no sound effects are being played to prevent wasting the battery) Is there anything better than a simple NPN transistor as a switch? (Better = lower battery drain with similar simplicity)