Hi,
We are trying to understand the operation of the power circuit switching in DV2004ES1 (components Q4, R12, Q3, D6, D9, Q2, R10 and R11 in page 5) without success.
What is the porpouse of D6 in this circuit? It seems to us that Q3 will never go to active region, as Ie current would necessarily go through D6 (considering that current going in the Q4 gate is negligible), meaning that Vb = Ve - ~0,5V. Is it right?
This understanding is necessary for us to being able to make some small changes in the circuit (replacing the BJTs for FETs, for example).
Thanks in advance for your support!