IP1203PBF 데이터 시트보기 (PDF) - International Rectifier
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IP1203PBF Datasheet PDF : 23 Pages
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iP1203PbF
Applying the Safe Operating Area (SOA) Curve
The SOA graph incorporates power loss and thermal resistance information in a way that allows one to solve for maximum
current capability in a simplified graphical manner. It incorporates the ability to solve thermal problems where heat is drawn
out through the printed circuit board and the top of the case.
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Procedure
Case Temperature (ºC)
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1) Draw a line from Case Temp axis at TCASE to the PCB
Temp axis at TPCB.
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2) Draw a vertical line from the TX axis intercept to the SOA 10
curve. (see AN-1047 for further explanation of TX )
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3) Draw a horizontal line from the intersection of the vertical 6
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TX
line with the SOA curve to the Y axis. The point at which
VIN = 12V
iP1203 SOA
4 VOUT = 1.5V
the horizontal line meets the y-axis is the SOA current.
fSW = 300kHz
4) If no top sided heatsinking is available, assume TCASE
2 L=1.0uH
temperature of 125°C for worst case performance.
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PCB Temperature (ºC)
Adjusting the Power Loss and SOA Curves for Different Operating Conditions
To make adjustments to the power loss curves in Fig. 2, multiply the normalized value obtained from the curves in Figs. 4,
5, 6 or 7 by the value indicated on the power loss curve in Fig. 2. Then 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. 2. The resulting
product is the final power loss based on all factors. See example no. 1.
To make adjustments to the SOA curve in Fig. 3, determine your maximum PCB Temp & Case Temp at the maximum
operating current of each iP1203PbF. Then, add the correction temperature from the normalized curves in Figs. 4, 5, 6 or
7 to the TX axis intercept (see procedure no. 2 above) in Fig. 3. When multiple adjustments are required, add all of the
temperatures together, then add the sum to the TX axis intercept in Fig. 3. See example no. 2.
Operating Conditions for the following examples:
Output Current = 12A
Output Voltage = 1.2V
Input Voltage = 13.2V
Sw Freq= 400kHz
Inductor = 0.6µH
Example 1) Adjusting for Maximum Power Loss:
(Fig. 2) Maximum power loss = 4.1W
(Fig. 4) Normalized power loss for input voltage ≈ 1.025
(Fig. 5) Normalized power loss for output voltage ≈ 0.97
(Fig. 6) Normalized power loss for frequency ≈ 1.08
(Fig. 7) Normalized power loss for inductor value ≈ 1.08
Adjusted Power Loss = 4.1 x 1.025 x 0.97 x 1.08 x 1.08 ≈ 4.75W
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