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4

iP1001

Fig 1. Power Loss vs Current

Fig 2. Safe Operating Area (SOA) vs T

PCB

Adjusting the Power Loss and SOA curves for different operating conditions

To make adjustments to the power loss curves in Fig. 1, multiply the normalized value obtained from the curves in Figs. 3,

or 4 by the value indicated on the power loss curve in Fig. 1. If multiple adjustments are required, multiply all of the

normalized values together, then multiply that product by the value indicated on the power loss curve in Fig. 1. The resulting

product is the final power loss based on all factors.

To make adjustments to the SOA curve in Fig. 2, determine the maximum allowed PCB temperature in Fig. 2 at the required

operating current. Then, add the correction temperature from the normalized curves in Figs. 3 or 4 to find the final maximum

allowable PCB temperature. When multiple adjustments are required, add all of the temperatures together, then add the sum

to the PCB temperature indicated on the SOA graph to determine the final maximum allowable PCB temperature based on

all factors.

Note: If input voltage <5Vin nominal operation is required then first see Fig. 5 for maximum current capability limit.

Operating Conditions for the examples below:

Output Current = 20A

Input Voltage = 7V

Output Voltage = 2.5V

Adjusting for Maximum Power Loss:

(Fig. 1)

Maximum power loss

(Fig. 3)

Normalized power loss for output voltage

≈1.14

(Fig. 4)

Normalized power loss for input voltage

≈0.89

Adjusted Power Loss = 5W x 0.89 x 1.14

Adjusting for SOA Temperature:

(Fig. 2)

SOA PCB Temperature = 90°C

(Fig. 3)

Normalized SOA PCB Temperature for output voltage

(Fig. 4)

Normalized SOA PCB Temperature for input voltage

Adjusted SOA PCB Temperature = 90°C + 4°C -4.5°C

Guaranteed Performance Curves

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0

2

4

6

8

10

12

14

16

18

20

Output Current (A)

Maximum

Typical

0

2

4

6

8

10

12

14

16

18

20

22

0

1020

30405060

708090 100 110 120 130

PCB Temperature (°C)

Safe Operating Area