MR750 MR751 MR752 MR754 MR756 MR758 MR760

3

Rectifier Device Data

Figure 5. Maximum Current Ratings

TL, LEAD TEMPERATURE (°C)

0

8.0

0

12

20

28

40

80

120

160

200

Figure 6. Maximum Current Ratings

0

8.0

4.0

0

16

24

32

IF(AV), AVERAGE FORWARD CURRENT (AMPS)

Figure 7. Power Dissipation

5/8”

CAPACITANCE LOADS

8.0

12

16

RESISTIVE INDUCTIVE

LOADS

TA, AMBIENT TEMPERATURE (°C)

0

1.0

0

2.0

3.0

4.0

40

80

120

160

200

Figure 8. Steady State Thermal Resistance

f = 60 Hz

RESISTIVE INDUCTIVE LOADS

CAPACITANCE LOADS – 1

F & 3F

20

6

F

1

F & 3F

20 Iavg

TA(A)

TA(K)

TL(A)

TC(A)

TJ

TC(K)

TL(K)

PF

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. Lowest values occur when one

side of the rectifier is brought as close as possible to the heat sink as

shown below. Terms in the model signify:

TA = Ambient Temperature

TC = Case Temperature

TL = Lead Temperature

TJ = Junction Temperature

RqS = Thermal Resistance, Heat Sink to Ambient

RqL = Thermal Resistance, Lead to Heat Sink

RqJ = Thermal Resistance, Junction to Case

PF = Power Dissipation

(Subscripts A and K refer to anode and cathode sides, respectively.)

Values for thermal resistance components are:

RqL = 40°C/W/in. Typically and 44°C/W/in Maximum.

RqJ = 2°C/W typically and 4°C/W Maximum.

Since RqJ is so low, measurements of the case temperature, TC, will be

approximately equal to junction temperature in practical lead mounted

applications. When used as a 60 Hz rectifierm the slow thermal response

holds TJ(PK) close to TJ(AVG). Therefore maximum lead temperature may

be found from: TL = 175°–R

θJL PF. PF may be found from Figure 7.

The recommended method of mounting to a P.C. board is shown on the

sketch, where R

θJA is approximately 25°C/W for a 1–1/2” x 1–1/2” copper

surface area. Values of 40

°C/W are typical for mounting to terminal strips

or P.C. boards where available surface area is small.

Board Ground Plane

Recommended mounting for half wave circuit

24

28

32

0

1/4

5.0

0

1/2

3/4

1.0

L, LEAD LENGTH (INCHES)

SINGLE LEAD TO HEAT SINK,

INSIGNIFICANT HEAT FLOW

THROUGH OTHER LEAD

10

15

20

25

30

35

40

24

16

4.0

20

60

100

140

180

4.0

12

20

28

1/8

3/8

5/8

7/8

BOTH LEADS TO HEAT

SINK WITH LENGTHS

AS SHOWN

3/8”

1/4”

L = 1/8”

20

60

100

140

180

5.0

6.0

7.0

I(pk) = 5 Iavg

I(pk) = 10 Iavg

I(pk) = 20 Iavg

10 Iavg

I(pk) = 5 Iavg

RESISTIVE – INDUCTIVE LOADS

BOTH LEADS TO HEAT

SINK, EQUAL LENGTH

6

F (IPK/IAVE = 6.28)

SEE NOTE

R

θJA = 40°C/W

SEE NOTE

R

θJA = 25°C/W

NOTES

THERMAL CIRCUIT MODEL

(For Heat Conduction Through The Leads)