I use the Nucleo-L152 and if I remove the jumper 6 and jumper 5, I get a voltage between +3V3 and VDD of 2.5V and a current of 750uA. Can you explain where this voltage and current are coming from?

[JMene.1]

..

[KnarfB]

There are signal pins (SWD, UART) from ST-LINK MCU to the L152RE which will "power" the L152RE when Vdd is not connected (J5 open). The GPIO protection diodes are then in the forward direction, which also explains the voltage drop of ~0.7V

hth

KnarfB