JW150A データシートの表示（PDF） - Tyco Electronics

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JW150A

Power Modules: dc-dc Converters; 36 to 75 Vdc Input, 5 Vdc Output; 50 W to 150 W

Tyco Electronics 

Data Sheet

July 1999

JW050A, JW075A, JW100A, JW150A Power Modules:

dc-dc Converters; 36 to 75 Vdc Input, 5 Vdc Output; 50 W to 150 W

Thermal Considerations

Heat Transfer Without Heat Sinks

Introduction

The power modules operate in a variety of thermal

environments; however, sufficient cooling should be

provided to help ensure reliable operation of the unit.

Heat-dissipating components inside the unit are ther-

mally coupled to the case. Heat is removed by conduc-

tion, convection, and radiation to the surrounding

environment. Proper cooling can be verified by mea-

suring the case temperature. Peak temperature (TC)

occurs at the position indicated in Figure 26.

7.6 (0.3)

38.0 (1.50)

VI (+)

ON/OFF

CASE

VI (–)

MEASURE CASE

TEMPERATURE HERE

VO (+)

+ SEN

TRIM

– SEN

VO (–)

Note: Top view, pin locations are for reference only.

Measurements shown in millimeters and (inches).

Figure 26. Case Temperature Measurement

Location

8-716 (C).f

Increasing airflow over the module enhances the heat

transfer via convection. Figure 27 shows the maximum

power that can be dissipated by the module without

exceeding the maximum case temperature versus local

ambient temperature (TA) for natural convection

through 4 m/s (800 ft./min.).

Note that the natural convection condition was mea-

sured at 0.05 m/s to 0.1 m/s (10 ft./min. to 20 ft./min.);

however, systems in which these power modules may

be used typically generate natural convection airflow

rates of 0.3 m/s (60 ft./min.) due to other heat dissipat-

ing components in the system. The use of Figure 27 is

shown in the following example.

Example

What is the minimum airflow necessary for a JW100A

operating at VI = 54 V, an output current of 20 A, and a

maximum ambient temperature of 40 °C?

Solution

Given: VI = 54 V

IO = 20 A

TA = 40 °C

Determine PD (Use Figure 30.):

PD = 17 W

Determine airflow (v) (Use Figure 27.):

v = 2.0 m/s (400 ft./min.)

The temperature at this location should not exceed

100 °C. The output power of the module should not

exceed the rated power for the module as listed in the

Ordering Information table.

Although the maximum case temperature of the power

modules is 100 °C, you can limit this temperature to a

lower value for extremely high reliability.

For additional information on these modules, refer to

the Thermal Management JC-, JFC-, JW-, and JFW-

Series 50 W to 150 W Board-Mounted Power Modules

Technical Note

(TN97-008EPS).

35

4.0 m/s (800 ft./min.)

30

3.5 m/s (700 ft./min.)

3.0 m/s (600 ft./min.)

2.5 m/s (500 ft./min.)

25

2.0 m/s (400 ft./min.)

1.5 m/s (300 ft./min.)

20

1.0 m/s (200 ft./min.)

0.5 m/s (100 ft./min.)

15

10

5 0.1 m/s (NAT. CONV.)

(20 ft./min.)

0

0 10 20 30 40 50 60 70 80 90 100

LOCAL AMBIENT TEMPERATURE, TA (°C)

8-1150 (C).a

Figure 27. Forced Convection Power Derating with

No Heat Sink; Either Orientation

Tyco Electronics Corp

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