DPA422 datasheet(17/36 Pages) POWERINT

17 / 36 page

Rev. S 12/07

DPA422-426

www.powerint.com

Forward power tables: Tables 1 (upper half), 3 and 4

Output power ﬁgures are based on forward topology using

Schottky diode rectiﬁcation. Up to 5% higher output power is

possible using synchronous rectiﬁcation.

Dissipation data assumes a diode loss representing 6% of the

total output power and combined loss in magnetic compo-

nents representing 6% of the total output power.

DPA-Switch losses are based on a ratio between conduction

and switching losses of approximately 3:1. These assump-

tions are typical for a single 5 V output forward converter

design using Schottky rectiﬁcation and adequately designed

magnetic components.

Flyback power tables: Tables 1 (lower half), 5 and 6

Output power and dissipation ﬁgures are based on a 5 V

output using Schottky diode rectiﬁcation with an efﬁciency of

85%. Values are generated by calculation based on

I2 × R

DS(ON) losses and characterization of switching losses,

correlated to bench measurement of each DPA-Switch device.

Device dissipations above 1.5 W are possible using the

R package. However the forward converter topology is

recommended for such higher power designs.

The power tables provide two types of information. The ﬁrst is

the expected device dissipation for a given output power. The

second is the maximum power output. Each table speciﬁes the

input voltage range and assumes a single 5 V output using

Schottky diode rectiﬁcation.

For example, referring to Table 1, for 36 VDC to 75 VDC input

range, DPA424 would typically dissipate 1 W in a 23 W forward

converter and has a maximum power capacity of 35 W. In the

same converter, DPA425 would dissipate 0.5 W. Selecting

DPA425 with associated reduced dissipation would increase

overall converter efﬁciency by approximately 2%.

Issues Affecting Dissipation:

Using synchronous rectiﬁcation will tend to reduce device

dissipation.

Designs with lower output voltages and higher currents will

tend to increase the device dissipation listed in the power

table.

Reduced input voltage decreases the available output power

for the same device dissipation. Tables 3 to 6 are the power

tables for 16 VDC and 24 VDC input voltages. Input voltages

below 16 V are possible, but since the internal start-up

current source is not speciﬁed at voltages below 16 V, an

external chip supply current should be fed into the

CONTROL pin approximately equal to but less than I

CD1.

DPA-Switch Selection

Use Tables 1 and 3 through 6 to select the DPA-Switch based

on device dissipation. Selecting the optimum DPA-Switch

depends upon required maximum output power, efﬁciency,

heat sinking constraints and cost goals. With the option to

externally reduce current limit, a larger DPA-Switch may be

used for lower power applications where higher efﬁciency is

needed or minimal heat sinking is available. Generally, selecting

the next larger device, than is required for power delivery will

give the highest efﬁciency. Selecting even larger devices may

•

Output Power Table

16-32 VDC Range (Forward)2

Total Device

Dissipation

Product3

0.5 W

1 W

2.5 W

4 W

6 W

Max

Power

Output1

DPA422

3.5 W

4.5 W

5.0 W

DPA423

5 W

7 W

7.5 W

DPA424

7 W

10 W

15 W

15.5 W

DPA425

10 W

14 W

22 W

27 W

31 W

DPA426

12 W

16.5 W

25 W

31 W

37 W

43 W

Table 3.

Output Power Table for 16-32 VDC Input Voltage.

Notes:

1. Limited by device internal current limit.

2. See text in this section for a complete description of assumptions.

3. See Part Ordering Information.

Output Power Table

16-32 VDC Input Range (Flyback)2

Total Device

Dissipation

Product3

0.5 W

0.75 W

1 W

1.5 W

Max

Power

Output1

DPA422

3 W

4.5 W

DPA423

5 W

6 W

DPA424

6.5 W

8.5 W

10 W

11 W

DPA425

7 W

10 W

12 W

15 W

22 W

Output Power Table

24-48 VDC Range (Forward)2

Total Device

Dissipation

Product3

0.5 W

1 W

2.5 W

4 W

6 W

Max

Power

Output1

DPA422

5.5 W

7 W

8 W

DPA423

8 W

11 W

11.5 W

DPA424

11 W

16 W

23.5 W

25 W

DPA425

16 W

22 W

35 W

43 W

47 W

DPA426

18 W

25 W

39 W

48 W

58 W

65 W

Table 4.

Output Power Table for 24-48 VDC Input Voltage

(See Table 3 for Notes).

Table 5.

Flyback Output Power Table for 16-32 VDC Input Voltage

(See Table 3 for Notes).

Output Power Table

24-48 VDC Input Range (Flyback)2

Total Device

Dissipation

Product3,4

0.5 W

0.75 W

1 W

1.5 W

Max

Power

Output1

DPA422

3 W

7 W

DPA423

7 W

8.5 W

DPA424

8.5 W

11.5 W

14 W

17 W

Table 6.

Flyback Output Power Table for 24-48 VDC Input Voltage.

Notes:

1. Maximum output power is limited by device internal current limit.

2. See text in this section for a complete description of assumptions.

3. See Part Ordering Information.

4. Higher switching losses may prevent DPA425 from delivering more power than a

smaller device.

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