L
Lessie
Guest
The schematic concerned is at the end of the microchip
document on microchip serial programming
http://ww1.microchip.com/downloads/en/AppNotes/91013b.pdf
The circuit generates VPP for the programming phase. D1 is
the reference of 12.7V and Q2 forms a negative feedback
with the opamp. This part I do understand. However, Q2 is
strange, what does it do? It seems that it will be in a
cut out state because base will be higher than emitter by
0.6V due to Q2 ?
document on microchip serial programming
http://ww1.microchip.com/downloads/en/AppNotes/91013b.pdf
The circuit generates VPP for the programming phase. D1 is
the reference of 12.7V and Q2 forms a negative feedback
with the opamp. This part I do understand. However, Q2 is
strange, what does it do? It seems that it will be in a
cut out state because base will be higher than emitter by
0.6V due to Q2 ?