Soft Power Switch Mk2 - JST 2mm

The Soft Power Switch Mk2 is a passive hard on/off switch with software feedback and control. In other words it's like the on/off switch on a laptop. A simple press will turn the system on. Another press can (with MCU intervention) turn off the system. And if things go really wrong pressing and holding the button for ~10 seconds will force a power-down. If you're building something with an enclosed battery and need a good power button this is the board you need. The Mk1 Soft Power Switch is great but we do see occasional issues caused by component tolerances or the operating temperature. Mk2 is based on an application note by Texas Instruments and is a completely digital design. It is based around a 74LVC1G175 D-type flip-flop - remember those?! - and is insensitive to temperature and component variation. It also includes improvements like: an over-current self-resetting 2A fuse; input and output LEDs. This version has JST 2mm battery connector. The PUSH pin can act as an output to a microcontroller indicating the state of the power button (high = not pressed low = user is pressing power button). This can be used as an input to your firmware to begin to shut down before power is lost. Alternatively the OFF pin can be driven high by the system forcing fast power off via software. (For Mk1 the Fast Off pin was driven low.) The most common use case is something like this: Microcontroller begins running code and checks to see if the power button is still being pressed for X milliseconds. If not it's just a tap go back to sleep. If yes power up and run normal program. Later... User presses power button in normal program If power button is pressed for If power button is pressed for >X milliseconds it's time to power down. The wake-up and power-down times can be tweaked for your own user experience but we found 500ms for power up and 2s for power down work really well. If needed pads are provided for a larger external button. The Soft Power Switch supports battery charging. If the target device has onboard LiPo charging current can be passed back through the switch circuit and charge the battery. Heads up! The Mk2 Soft Power Switch works up to 5.5V only. (Mk1 is good up to 12V.) Pros: Very low quiescent current: