PD-60325

iP2005APbF

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 iP2005A and obtain the maximum power loss

from Figure 1

2.Use the normalized curves 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 iP2005A

2.Use the normalized curves to obtain SOA temperature adjustments that match the

operating conditions in the application

3.Then, add the sum of the SOA temperature adjustments to the T

2

Design Example

Operating Conditions:

Output Current = 30A

Input Voltage = 10V

Output Voltage = 1.3V

Switching Freq = 750kHz Inductor = 0.2µH

Drive Voltage (V

Calculating Maximum Power Loss:

(Figure 1)

Maximum power loss = 9.0W

(Figure 3)

Normalized power loss for input voltage

≈ 0.95

(Figure 4)

Normalized power loss for output voltage

≈ 1.0

(Figure 5)

Normalized power loss for output inductor

≈ 1.026

(Figure 6)

Normalized power loss for switch frequency

≈ 0.87

Calculated Maximum Power Loss

≈ 9.0W x 0.95 x 1.0 x 1.026 x 0.87 ≈ 7.63W

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2/8/2008

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