MBR1100
3Rectifier Device Data
NOTE 1 — MOUNTING DATA:
Data shown for thermal resistance junction–to–ambient
(RθJA) for the mountings shown is to be used as typical
guideline values for preliminary engineering or in case the tie
point temperature cannot be measured.
Typical Values for RθJA in Still Air
Mounting Lead Length, L (in)
Method 1/8 1/4 1/2 3/4
θJA
152 65 72 85 °C/W
2 67 80 87 100 °C/W
3 — 50 °C/W
Mounting Method 1
P.C. Board with
1–1/2″ x 1–1/2″
copper surface.
Mounting Method 3
P.C. Board with
1–1/2″ x 1–1/2″
copper surface.
BOARD GROUND
PLANE
VECTOR PIN MOUNTING
Mounting Method 2
LL
LL
L = 3/8
″
NOTE 2 — THERMAL CIRCUIT MODEL:
(For heat conduction through the leads)
TA(A) TA(K)
TL(A) TC(A) TJTC(K) TL(K)
PD
R
θ
S(A) R
θ
L(A) R
θ
J(A) R
θJ(K)
R
θ
L(K) R
θ
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:
TA = Ambient Temperature TC = Case Temperature
TL = Lead Temperature TJ = Junction Temperature
RθS = Thermal Resistance, Heat Sink to Ambient
RθL = Thermal Resistance, Lead to Heat Sink
RθJ = Thermal Resistance, Junction to Case
PD = Power Dissipation
(Subscripts A and K refer to anode and cathode sides,
respectively.) Values for thermal resistance components are:
RθL = 100°C/W/in typically and 120°C/W/in maximum.
RθJ = 36°C/W typically and 46°C/W maximum.
NOTE 3 — HIGH FREQUENCY OPERATION:
Since current flow in a Schottky rectifier is the result of ma-
jority carrier conduction, it is not subject to junction diode for-
ward 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 2.0 MHz, e.g., the ratio of dc power to RMS power
in the load is 0.28 at this frequency , whereas perfect rectifica-
tion would yield 0.406 for sine wave inputs. However, in con-
trast 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.