Transcript
DC Power supply
DC Vout
RL
AC ~110V ±10% 60 Hz
DC out
RL
AC ~110V ±10% 60 Hz
?
VZ
Vin
RS
Zener diode shunt voltage regulator
Vout = VZ
I = (Vin-Vz) /Rs
Example:
Vin = 12 V
Vz = 6 V
I = 1 A
W = 12 w
Drawbacks:
• Heat
• Vz fixed
I Vout = VZ – 0.6 V
I max = *I
VZ
Vin
RS
Ib
Add an emitter follower
VZ
Vin
RS
I
Ib
A convention
Vin
RS
I
Adjustable Vout
R1
R3
R4
+VinVout
Vout =R3 + R4
R4
VBE
Using feedback
R1
R3
R4
+VinVout
Vout =R3 + R4
R4
(VBE + Vz)Improvement
+VinVoutR4
Current limiting
R1
VZ
R2
R3
+Vin
Vout =R2 + R3
R3
VZ Using an op. amp.
LM78 XXV+ in 2
3
Available XX :
05, 08, 09, 10, 12, 15, 18, 24 (V), and etc.
1
V- in LM79 XX V- out
LM117/317Vin Vout
A review of JFET
p
n p
np n
Transistors
MOSFET
+
+
-
-
-
n
-
+
+
+
+
+
+
n-SiAl
SiO2
D
S
G
Transistors
R1
R3
R4
+Vin
Vout
Vout =R3 + R4
R4
VBE