---
tags:
  - resource
created: 2026-07-08 17:24
---
## Summary

Each board contains four identical circuits using BSS138 MOSFETs. The ground pins are not connected to the circuit in any way and are not needed for it to function. A low level output is sinked through the corresponding input signal (MCU GPIO pin). A high level output is sourced through the corresponding Vin pin (LV or HV) through a 10k resistor. If an input is left floating, the corresponding output will go high. If using unidirectionally you can put a strong pull down resistor (1k) on the input side. A pull down on the output side will cause malfunction.

## References

![[level_shifter_circuit_diagram.jpg.jpg]]

![[level_shifter_board_pic.jpg]]