1. MALVINO
Electronic
PRINCIPLES
SIXTH EDITION

2. Diode Circuits
Chapter 4

3. The half-wave rectifierVP
The half-wave
rectifier
Vin
Vout
Vin
Ideal: VP(in) = VP(out)
Vout

4. Half-wave rectifier The dc value of the output is the average value.
Vdc = VP/p
fout = fin
Second approximation: VP(out) = VP(in) V

5. Transformer review
When the turns ratio (N1/N2) is greater than 1, the primary voltage is stepped down.
When the turns ratio is less than 1, the primary voltage is stepped up.
Dotted ends have the same instantaneous phase.
Full-wave rectifiers require a winding with a center tap.

6. The full-wave rectifier
Vin
Vout
C.T.
Vout

7. Full-wave rectifier The dc value of the output is the average value.
Vdc = 2VP/p
fout = 2fin
The input to each diode is half the secondary voltage.
Second approximation: VP(out) = VP(in) V

8. The bridge
rectifier
Vin
Vout
Vout

9. Bridge rectifier The dc value of the output is the average value.
Vdc = 2VP/p
fout = 2fin
Second approximation: VP(out) = VP(in) V

10. The choke-input filterRL
Vout
Vin
When XL >> XC: XC
Vout @ XL
Vin

11. The capacitor-input filter
Discharge VP +
Charge -
VR = I fC
Where VR is the peak-to-peak ripple voltage

12. Dc output voltage drops when load current increases
Ac line regulation can have an effect
Bulk resistance of rectifiers causes a voltage drop
Resistance of transformer windings causes a voltage drop
Ac ripple increases and average dc decreases

13. Diode ratings
Half-wave rectifier with capacitor-input filter: PIV = 2VP Idiode = Idc
Full-wave rectifier with capacitor-input filter: PIV = VP Idiode = Idc
Bridge rectifier with capacitor-input filter: PIV = VP Idiode = 0.5Idc

14. Bridge supply troubleshooting
No output - - blown fuse, two or more diodes open, load shorted
Low output/extra ripple - - bad filter, open diode, shorted winding, overload
Full-wave signal at output - - open filter capacitor
Half-wave ripple frequency - - open diode

15. Positive clipper RS
0.7 V
Vin RL
Vout

16. Negative clipper RS
Vin RL
Vout
-0.7 V

17. Stiff clamper: RLC > 100T
Positive clamper C RL
Vout
-0.7 V
Stiff clamper: RLC > 100T

18. Stiff clamper: RLC > 100T
Negative clamper C
0.7 V RL
Vout
Stiff clamper: RLC > 100T

19. Half-wave voltage doublerC1 D1 VP C2 D2
2VP

20. Full-wave voltage doublerVP VP
2VP