P_CH_I_REG PUBLIC

Current regulator based on P-Channel MOSFET. Adjust R1 to change current - voltage drop should equal Q2's V-EB threshold.

Current flows primarily through R1, causing V-drop across Q2's EB junction. When Q2's threshold is reached, it switches on pulling M1's gate higher - and therefor resisting additional current flow. When current flow is insufficient, R2 pulls M1's gate lower, increasing the MOSFETs conduction. Power on MOSFET will be (V-DROP - V_R1 )* I_TOTAL as it will stabilize in linear mode.

Just an amateur, so comments/improvements very welcome. Posting because I could not find a P-Ch regulator on the net anywhere - thought someone may find it useful.