
MBR1100
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3
Figure 5. Typical Capacitance
20
40
0
V
R
, REVERSE VOLTAGE (VOLTS)
150
50
40
30
20
15
30
C
50
100
60
100
90
80
10
70
80
90
70
60
T
J
= 25
°
C
f
TEST
= 1 MHz
NOTE 3 — MOUNTING DATA:
Data shown for thermal resistance junctiontoambient
(R
JA)
for the mounting shown is to be used as a typical
guideline values for preliminary engineering or in case the
tie point temperature cannot be measured.
Typical Values for
R
JA
in Still Air
Mounting
Method
Lead Length, L (in)
R
JA
1/8
1/4
1/2
3/4
1
52
65
72
85
°
C/W
2
67
80
87
100
°
C/W
3
—
50
°
C/W
Mounting Method 1
P.C. Board with
11/2
″
x 11/2
″
copper surface.
Mounting Method 3
P.C. Board with
11/2
″
x 11/2
″
copper surface.
BOARD GROUND
PLANE
Mounting Method 2
éééééééé
éééééééé
L
L
éééééééé
éééééééé
é
é
é
é
L = 3/8
″
NOTE 4 — THERMAL CIRCUIT MODEL:
(For heat conduction through the leads)
T
A(A)
T
A(K)
T
L(A)
T
C(A)
T
J
T
C(K)
T
L(K)
P
D
R
S(A)
R
L(A)
R
J(A)
R
J(K
)
R
L(K)
R
S(K)
Use of the above model permits junction to lead thermal
resistance for any mounting configuration to be found. For
a given total lead length, lowest values occur when one side
of the rectifier is brought as close as possible to the heat sink.
Terms in the model signify:
T
A
= Ambient Temperature
T
L
= Lead Temperature
R
S
= Thermal Resistance, Heat Sink to Ambient
R
L
= Thermal Resistance, Lead to Heat Sink
R
J
= Thermal Resistance, Junction to Case
P
D
= Power Dissipation
T
C
= Case Temperature
T
J
= Junction Temperature
(Subscripts A and K refer to anode and cathode sides,
respectively.) Values for thermal resistance components are:
R
L
= 100
°
C/W/in typically and 120
°
C/W/in maximum.
R
J
= 36
°
C/W typically and 46
°
C/W maximum.
NOTE 5 — HIGH FREQUENCY OPERATION:
Since current flow in a Schottky rectifier is the result of
majority carrier conduction, it is not subject to junction
diode forward and reverse recovery transients due to
minority carrier injection and stored charge. Satisfactory
circuit analysis work may be performed by using a model
consisting of an ideal diode in parallel with a variable
capacitance. (See Figure 5)
Rectification efficiency measurements show that
operation will be satisfactory up to several megahertz. For
example, relative waveform rectification efficiency is
approximately 70 percent at 2 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
diodes, 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.