HWD075DGE-A(2003) Ver la hoja de datos (PDF) - Power-One Inc.

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Fabricante

HWD075DGE-A
(Rev.:2003)

75 Watt, Half-Brick DC/DC Converter

Power-One Inc. 

HWD DC/DC Series Data Sheet

Output Voltage Adjustment

Output voltage adjustment is accomplished by connecting an external resistor between the Trim Pin and either the

+Vo1 or –Vo1 Pins.

With an external resistor between the Trim Pin and +Vo1 Pin (Radj-down) the output voltage set point (Vo,adj)

decreases. The following equation determines the required external resistor value to obtain an adjusted output

voltage:

[ ] Radj, dn=

(Vo, adj - D) A

- B ohm

Vo, nom -Vo, adj

Where Radj-down is the resistance value and A, B, and D are defined in Table 7.

With an external resistor between the Trim Pin and –Vo1 Pin (Radj-up) the output voltage set point (Vo,adj)

increases. The following equation determines the required external resistor value to obtain an adjusted output

voltage:

[ Radj, up=

A•D

]- B ohm

(Vo, adj - D) - C

Where Radj-up is the resistance value and A, B, C, and D are defined in Table 12.

Table 12.Output Adjustment Variables

Output

A

B

C

D

Vo1

4990

2000

2.5

2.5

Vo2

4990

2000

0.8

2.5

THERMAL CONSIDERATIONS

The power converter operates in a variety of thermal environments: however, sufficient cooling should be provided

to help ensure reliable operation of the converter. Heat-dissipating components are thermally coupled to the case.

Heat is removed by conduction, convection, and radiation to the surrounding environment. Proper cooling can be

verified by measuring the case temperature.

Heat Transfer Characteristics

Increasing airflow over the converter enhances the heat transfer via convection. Figure 4 shows the maximum

power that can be dissipated by the converter without exceeding the maximum case temperature versus local

ambient temperature (TA) for natural convection through 400 ft/min.

Systems in which these converters are used generate airflow rates of 50 ft/min due to other heat dissipating

components in the system. Therefore, the natural convection condition represents airflow rates of approximately

50 ft/min. Use of Figure 4 is shown in the following example.

Example

What is the minimum airflow required for the device operating at 24 V, an output power of 60 W, and maximum

ambient temperature of 60 ºC.

Solution:

Given: Vi = 24 V, Po = 60 W, TA = 60 ºC.

Determine PD (Figure 4): PD = 13 W.

Determine airflow (Figure 4): v = 200 ft/min

REV. JUN 27, 2003

Page 8 of 12

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