MBR2045CT, MBRF2045CT

http://onsemi.com

6

HIGH FREQUENCY OPERATION

Since current flow in a Schottky rectifier is the result of

majority carrier conduction, it is not subject to junction di-

ode forward and reverse recovery transients due to minority

carrier injection and stored charge. Satisfactory circuit ana-

lysis work may be performed by using a model consisting

of an ideal diode in parallel with a variable capacitance.

(See Figure 12.)

Rectification efficiency measurements show that opera-

tion will be satisfactory up to several megahertz. For ex-

ample, relative waveform rectification efficiency is ap-

proximately 70 percent at 2.0 MHz, e.g., the ratio of dc

power to RMS power in the load is 0.28 at this frequency,

whereas perfect rectification would yield 0.406 for sine

wave inputs. However, in contrast to ordinary junction di-

odes, the loss in waveform efficiency is not indicative of

power loss; it is simply a result of reverse current flow

through the diode capacitance, which lowers the dc output

voltage.

2.0

ms

1.0 kHz

12 V

100

12 Vdc

2N2222

CURRENT

AMPLITUDE

ADJUST

0-10 AMPS

100

CARBON

2N6277

1.0 CARBON

1N5817

D.U.T.

2.0 k

W

+150 V, 10 mAdc

4.0

mF

+

1000

500

300

0

050

700

Figure 12. Typical Capacitance

10

20

30

200

40

Figure 13. Test Circuit for dv/dt and Reverse Surge Current

f = 1 MHz

100

600

400

800

900