MR750 SERIES
100
70
T
J
= 175°C
CURRENT INPUT WAVEFORM
30
T
J
= 25°C
t rr , REVERSE RECOVERY TIME (
m
s)
RELATIVE EFFICIENCY (%)
30
20
T
J
= 25°C
10
7.0
5.0
3.0
2.0
1.0
0.1
0
I
R
t
rr
0.2
0.3
0.5 0.7 1.0
2.0
3.0
5.0 7.0 10
I
F
= 5 A
3A
1A
I
F
50
20
1.0
2.0 3.0
5.0 7.0 10
20
30
50
70 100
REPETITION FREQUENCY (kHz)
I
R
/I
F
, RATIO OF REVERSE TO FORWARD CURRENT
Figure 9. Rectification Efficiency
1000
700
500
C, CAPACITANCE (pF)
300
200
100
70
50
30
20
10
1.0
2.0
3.0
5.0 7.0 10
20
30
50
70 100
V
R
, REVERSE VOLTAGE (VOLTS)
1.0
t fr , FORWARD RECOVERY TIME (
m
s)
T
J
= 25°C
0.7
Figure 10. Reverse Recovery Time
u
f
t
fr
u
fr
T
J
= 25°C
0.5
u
fr
= 1.0 V
0.3
0.2
u
fr
= 2.0 V
0.1
1.0
2.0
3.0
5.0
7.0
10
I
F
, FORWARD PULSE CURRENT (AMP)
Figure 11. Junction Capacitance
Figure 12. Forward Recovery Time
R
S
R
L
V
O
For a square wave input of amplitude V
m
, the efficiency
factor becomes:
V
2m
2
R
L
σ
(square)
+
V
2m
.100%
+
50%
R
L
(3)
Figure 13. Single−Phase Half−Wave
Rectifier Circuit
The rectification efficiency factor
σ
shown in Figure 9
was calculated using the formula:
V
2
o
(dc)
R
L
R
L
(1)
V
2
o
(dc)
.100%
V
2
o
(
ac)
)
V
2
o
(dc)
σ
+
P
(dc)
P
(rms)
+
V
2
o
(rms)
.100%+
For a sine wave input V
m
sin (wt) to the diode, assumed
lossless, the maximum theoretical efficiency factor becomes:
V
2m
p
2
R
L
σ
(sine)
+
V
2m
.100%
+
4 .100%
+
40.6%
π
2
4R
L
(A full wave circuit has twice these efficiencies)
As the frequency of the input signal is increased, the
reverse recovery time of the diode (Figure 10) becomes
significant, resulting in an increasing AC voltage
component across R
L
which is opposite in polarity to the
forward current, thereby reducing the value of the efficiency
factor
σ,
as shown on Figure 9.
It should be emphasized that Figure 9 shows waveform
efficiency only; it does not provide a measure of diode
losses. Data was obtained by measuring the AC component
of V
o
with a true rms AC voltmeter and the DC component
with a DC voltmeter. The data was used in Equation 1 to
obtain points for Figure 9.
(2)
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