Soft Power Switch Mk2 - power switch with JST 2mm connector

Description

Soft Power Switch Mk2 is a passive power on/off switch with control and feedback options. It operates similarly to a laptop power button: a short press turns the system on, and a subsequent press (in cooperation with a microcontroller) can turn it off. In case of issues, holding the button for an extended period (about 10 seconds) forces a power cutoff. It is perfect for projects with a built-in battery where a reliable power button is required.

The Mk2 version switches to a fully digital design based on Texas Instruments and the 74LVC1G175 D-type flip-flop, eliminating issues with component tolerance and temperature changes that were present in the Mk1 version. Additional improvements include a self-resetting 2A fuse and LED indicators for input and output. This version also features a JST 2mm battery connector. The PUSH pin can serve as an output to the microcontroller, signaling the power button state (high means no press, low means the user is pressing the power button). This can be used as an input signal for the software to safely shut down the system before powering off. Alternatively, the OFF pin can be set to a high state to force an immediate shutdown via software.

Wake-up and shutdown times can be adjusted, but recommended values are 500 ms for power-on and 2 s for power-off. The board features pads for connecting an external larger button. The Soft Power Switch also supports battery charging – if the target device has a built-in LiPo charging function, current can be passed through the switch circuit for battery charging.

Features

• Input voltage: from 1.8 V to 5.5 V
• Maximum current consumption: 2A (continuous), 4A (peak)
• MOSFET transistors:
  • Type: SIL2308 N&P-Channel MOSFET
  • Typical P-Channel resistance: 70mΩ (0.070 Ohm)
• Low quiescent current: <1µA at 3.75V when VIN LED is off
• Button press of approximately 10 seconds forces power-off
• Supports battery charging
• LED indicators: VIN and VOUT
• Pinout:
  • GND, VIN, VOUT
  • BTN: Option to connect an external button between BTN and GND
  • PUSH: Open-drain output (requires pull-up); low state indicates button press
  • OFF: High output forces power off
• Dimensions: 25.4 x 25.4 mm