MBR150 MBR160

3

Rectifier Device Data

Figure 5. Steady–State Thermal Resistance

Figure 6. Typical Capacitance

3/4

0

L, LEAD LENGTH (INCHES)

90

80

60

70

50

VR, REVERSE VOLTAGE (VOLTS)

50

80

0

60

40

30

20

40

30

20

3/8

1/8

1/4

1/2

5/8

7/8

1.0

60

70

10

20

30

40

50

70

80

10

100

200

BOTH LEADS TO HEAT SINK,

EQUAL LENGTH

MAXIMUM

TYPICAL

100

90

TJ = 25°C

f = 1 MHz

NOTE 3 — MOUNTING DATA:

Data shown for thermal resistance junction–to–ambient

(R

θJA) 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

θJA in Still Air

Mounting

Lead Length, L (in)

R

θJA

g

Method

1/8

1/4

1/2

3/4

R

θJA

1

52

65

72

85

°C/W

2

67

80

87

100

°C/W

3

—

50

°C/W

NOTE 4 — THERMAL CIRCUIT MODEL:

(For heat conduction through the leads)

TA(A)

TA(K)

TL(A)

TC(A)

TJ

TC(K)

TL(K)

PD

R

θS(A)

R

θL(A)

R

θJ(A)

R

θJ(K)

R

θL(K)

R

θS(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

R

θS = Thermal Resistance, Heat Sink to Ambient

R

θL = Thermal Resistance, Lead to Heat Sink

R

θJ = Thermal Resistance, Junction to Case

PD = Power Dissipation

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

″

(Subscripts A and K refer to anode and cathode sides,

respectively.) Values for thermal resistance components are:

R

θL = 100°C/W/in typically and 120°C/W/in maximum.

R

θJ = 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 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 6.)

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 rectifica-

tion would yield 0.406 for sine wave inputs. However, in con-

trast to ordinary junction diodes, the loss in waveform effi-

ciency 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.