1N5820, 1N5821, 1N5822
125
TR , REFERENCE TEMPERATURE (
°
C)
20
125
10
8.0
TR , REFERENCE TEMPERATURE (
°
C)
15
20
115
15
10
8.0
115
105
R
qJA
(°C/W) = 70
95
50
40
85
75
2.0
3.0
4.0
5.0
7.0
10
15
20
V
R
, REVERSE VOLTAGE (VOLTS)
28
105
R
qJA
(°C/W) = 70
95
50
40
85
75
3.0
4.0
5.0
7.0
10
15
20
30
V
R
, REVERSE VOLTAGE (VOLTS)
28
Figure 1. Maximum Reference Temperature
1N5820
Figure 2. Maximum Reference Temperature
1N5821
125
TR , REFERENCE TEMPERATURE (
°
C)
20
R
q
JL , THERMAL RESISTANCE
JUNCTION−TO−LEAD (
°
C/W)
115
15
10
8.0
105
R
qJA
(°C/W) = 70
50
85
40
28
75
4.0
5.0
7.0
10
15
20
30
40
40
35
30
25
20
15
10
5.0
0
0
1/8
2/8
3/8
4/8
5/8
6/8
7/8
1.0
V
R
, REVERSE VOLTAGE (VOLTS)
L, LEAD LENGTH (INCHES)
BOTH LEADS TO HEATSINK,
EQUAL LENGTH
MAXIMUM
TYPICAL
95
Figure 3. Maximum Reference Temperature
1N5822
Figure 4. Steady−State Thermal Resistance
1.0
r(t), TRANSIENT THERMAL RESISTANCE
(NORMALIZED)
0.5
0.3
0.2
0.1
0.05
0.03
0.02
0.01
0.2
0.5
1.0
2.0
5.0
10
20
50
t, TIME (ms)
The temperature of the lead should be measured using a ther-
mocouple placed on the lead as close as possible to the tie point.
The thermal mass connected to the tie point is normally large
enough so that it will not significantly respond to heat surges
generated in the diode as a result of pulsed operation once
steady−state conditions are achieved. Using the measured val-
ue of T
L
, the junction temperature may be determined by:
T
J
= T
L
+
DT
JL
LEAD LENGTH = 1/4″
P
pk
t
p
t
1
P
pk
TIME
DUTY CYCLE = t
p
/t
1
PEAK POWER, P
pk
, is peak of an
equivalent square power pulse.
DT
JL
= P
pk
•
R
qJL
[D + (1 − D)
•
r(t
1
+ t
p
) + r(t
p
) − r(t
1
)] where:
DT
JL
= the increase in junction temperature above the lead temperature.
r(t) = normalized value of transient thermal resistance at time, t, i.e.:
r(t
1
+ t
p
) = normalized value of transient thermal resistance at time
t
1
+ t
p
, etc.
100
200
500
1.0 k
2.0 k
5.0 k
10 k
20 k
Figure 5. Thermal Response
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