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12/22/2007

Data Sheet No. PD60322

iP2004

Calculating Power Loss and SOA for Different Operating Conditions

To calculate Power Loss for a given set of operation conditions, the following procedure

should be followed:

Power Loss Procedure

1. Determine the maximum current for each iP2004 and obtain the maximum power loss

from Figure 1

2. Use the Normalized curves in page 5 to obtain power loss values that match the

operating conditions in the Application

3. The maximum power loss under the Application conditions is then the product of the

power loss from Figure 1 and the normalized values.

To calculate the Safe Operating Area (SOA) for a given set of operating conditions, the

following procedure should be followed:

SOA Procedure

1. Determine the maximum PCB and CASE temperature at the maximum operating

current for each iP2004

2. Use the Normalized curves in page 5 to obtain SOA temperature adjustments that

match the operating conditions in the Application

Figure 2

Design Example

Operating Conditions:

Output Current = 30A

Input Voltage = 10V

Output Voltage = 3.3V

Switching Freq = 750kHz

Inductor = 0.2µH

Calculating Maximum Power Loss:

(Figure 1)

Maximum power loss = 8.0W

(Figure 3)

Normalized power loss for input voltage

≈ 0.98

(Figure 4)

Normalized power loss for output voltage

≈ 1.23

(Figure 5)

(Figure 6)

Normalized power loss for output inductor

≈ 1.03

(Figure 7)

Normalized power loss for switch frequency

≈ 0.91

Calculated Maximum Power Loss

≈ 8.0W x 0.98 x 1.23 x 0.96 x 1.03 x 0.91 ≈ 8.68W