Epson PC AX Technical Manual page 36

PRINCIPLES OF OPERATION
L5
V
I N
O>-----.W
KEV.A
VOUT
GND
10
10
Q3
Z3
anode
100
51K
cathode
2.2 K
RV2
470n
GN 0
FIGURE 2-2-11. VOLTAGE STABILIZATION CIRCUIT
11
If the Vout voltage rises, the Vref voltage rises and then the cathode
current increases. After that the Q3 collector current increases, and the
Vout voltage decreases ---- Function 1
If the Vout voltage decrease, the Vref voltage decreases and the cathode
current decreases. After that the Q3 collector current decreases and the Vout
voltage rises -_._.- Function 2
CATHOOE
CURRENT
[A]
REFERENCE
VOLTAGE [V]
FIGURE 2-2-12. CHARACTERIZE OF Z3
2-8