Monday, April 9, 2018

Micro-controller Output Protection by Current Limiting

Q1B is the pass or output transistor. R2 sense the output current. Q1A  is the protection transistor which turns on as soon as the voltage across R2 becomes about 0.65 V.
Maximum current = VBE,Q1A / R2 = 0.65 / 33 = 19.7 mA

Hot-Swap Circuits with Inrush Current Limiter

  To provide continuous current sensing and limiting, this hot-swap circuit uses a PNP transistor and a current sense resistor of 0.333R. Wh...